draft-ietf-manet-dsr-09.txt   draft-ietf-manet-dsr-10.txt 
IETF MANET Working Group David B. Johnson, Rice University IETF MANET Working Group David B. Johnson, Rice University
INTERNET-DRAFT David A. Maltz, Carnegie Mellon University INTERNET-DRAFT David A. Maltz, Carnegie Mellon University
15 April 2003 Yih-Chun Hu, Rice University 19 July 2004 Yih-Chun Hu, Rice University
The Dynamic Source Routing Protocol The Dynamic Source Routing Protocol
for Mobile Ad Hoc Networks (DSR) for Mobile Ad Hoc Networks (DSR)
<draft-ietf-manet-dsr-09.txt> <draft-ietf-manet-dsr-10.txt>
Status of This Memo Status of This Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC 2026. of Section 10 of RFC 2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note Task Force (IETF), its areas, and its working groups. Note
that other groups may also distribute working documents as that other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
skipping to change at page 1, line 43 skipping to change at page 1, line 42
This Internet-Draft is a submission to the IETF Mobile Ad Hoc This Internet-Draft is a submission to the IETF Mobile Ad Hoc
Networks (MANET) Working Group. Comments on this draft may be sent Networks (MANET) Working Group. Comments on this draft may be sent
to the Working Group at manet@itd.nrl.navy.mil, or may be sent to the Working Group at manet@itd.nrl.navy.mil, or may be sent
directly to the authors. directly to the authors.
Abstract Abstract
The Dynamic Source Routing protocol (DSR) is a simple and efficient The Dynamic Source Routing protocol (DSR) is a simple and efficient
routing protocol designed specifically for use in multi-hop wireless routing protocol designed specifically for use in multi-hop wireless
ad hoc networks of mobile nodes. DSR allows the network to be ad hoc networks of mobile nodes. DSR allows the network to be
completely self-organizing and self-configuring, without the need completely self-organizing and self-configuring, without the need for
for any existing network infrastructure or administration. The any existing network infrastructure or administration. The protocol
protocol is composed of the two main mechanisms of "Route Discovery" is composed of the two main mechanisms of "Route Discovery" and
and "Route Maintenance", which work together to allow nodes to "Route Maintenance", which work together to allow nodes to discover
discover and maintain routes to arbitrary destinations in the ad hoc and maintain routes to arbitrary destinations in the ad hoc network.
network. All aspects of the protocol operate entirely on-demand, All aspects of the protocol operate entirely on-demand, allowing
allowing the routing packet overhead of DSR to scale automatically the routing packet overhead of DSR to scale automatically to only
to only that needed to react to changes in the routes currently in that needed to react to changes in the routes currently in use. The
use. The protocol allows multiple routes to any destination and protocol allows multiple routes to any destination and allows each
allows each sender to select and control the routes used in routing sender to select and control the routes used in routing its packets,
its packets, for example for use in load balancing or for increased for example for use in load balancing or for increased robustness.
robustness. Other advantages of the DSR protocol include easily Other advantages of the DSR protocol include easily guaranteed
guaranteed loop-free routing, support for use in networks containing loop-free routing, operation in networks containing unidirectional
unidirectional links, use of only "soft state" in routing, and very links, use of only "soft state" in routing, and very rapid recovery
rapid recovery when routes in the network change. The DSR protocol when routes in the network change. The DSR protocol is designed
is designed mainly for mobile ad hoc networks of up to about two mainly for mobile ad hoc networks of up to about two hundred nodes,
hundred nodes, and is designed to work well with even very high and is designed to work well with even very high rates of mobility.
rates of mobility. This document specifies the operation of the DSR This document specifies the operation of the DSR protocol for routing
protocol for routing unicast IPv4 packets. unicast IPv4 packets.
Contents Contents
Status of This Memo i Status of This Memo i
Abstract ii Abstract ii
1. Introduction 1 1. Introduction 1
2. Assumptions 3 2. Assumptions 4
3. DSR Protocol Overview 5 3. DSR Protocol Overview 6
3.1. Basic DSR Route Discovery . . . . . . . . . . . . . . . . 5 3.1. Basic DSR Route Discovery . . . . . . . . . . . . . . . . 6
3.2. Basic DSR Route Maintenance . . . . . . . . . . . . . . . 8 3.2. Basic DSR Route Maintenance . . . . . . . . . . . . . . . 9
3.3. Additional Route Discovery Features . . . . . . . . . . . 10 3.3. Additional Route Discovery Features . . . . . . . . . . . 11
3.3.1. Caching Overheard Routing Information . . . . . . 10 3.3.1. Caching Overheard Routing Information . . . . . . 11
3.3.2. Replying to Route Requests using Cached Routes . 11 3.3.2. Replying to Route Requests using Cached Routes . 12
3.3.3. Preventing Route Reply Storms . . . . . . . . . . 12 3.3.3. Route Request Hop Limits . . . . . . . . . . . . 13
3.3.4. Route Request Hop Limits . . . . . . . . . . . . 14 3.4. Additional Route Maintenance Features . . . . . . . . . . 14
3.4. Additional Route Maintenance Features . . . . . . . . . . 15 3.4.1. Packet Salvaging . . . . . . . . . . . . . . . . 14
3.4.1. Packet Salvaging . . . . . . . . . . . . . . . . 15
3.4.2. Queued Packets Destined over a Broken Link . . . 15 3.4.2. Queued Packets Destined over a Broken Link . . . 15
3.4.3. Automatic Route Shortening . . . . . . . . . . . 16 3.4.3. Automatic Route Shortening . . . . . . . . . . . 16
3.4.4. Increased Spreading of Route Error Messages . . . 17 3.4.4. Increased Spreading of Route Error Messages . . . 16
3.5. Optional DSR Flow State Extension . . . . . . . . . . . . 17 3.5. Optional DSR Flow State Extension . . . . . . . . . . . . 17
3.5.1. Flow Establishment . . . . . . . . . . . . . . . 18 3.5.1. Flow Establishment . . . . . . . . . . . . . . . 17
3.5.2. Receiving and Forwarding Establishment Packets . 19 3.5.2. Receiving and Forwarding Establishment Packets . 19
3.5.3. Sending Packets Along Established Flows . . . . . 19 3.5.3. Sending Packets Along Established Flows . . . . . 19
3.5.4. Receiving and Forwarding Packets Sent Along 3.5.4. Receiving and Forwarding Packets Sent Along
Established Flows . . . . . . . . . . . . 20 Established Flows . . . . . . . . . . . . 20
3.5.5. Processing Route Errors . . . . . . . . . . . . . 21 3.5.5. Processing Route Errors . . . . . . . . . . . . . 21
3.5.6. Interaction with Automatic Route Shortening . . . 21 3.5.6. Interaction with Automatic Route Shortening . . . 21
3.5.7. Loop Detection . . . . . . . . . . . . . . . . . 22 3.5.7. Loop Detection . . . . . . . . . . . . . . . . . 21
3.5.8. Acknowledgement Destination . . . . . . . . . . . 22 3.5.8. Acknowledgement Destination . . . . . . . . . . . 22
3.5.9. Crash Recovery . . . . . . . . . . . . . . . . . 22 3.5.9. Crash Recovery . . . . . . . . . . . . . . . . . 22
3.5.10. Rate Limiting . . . . . . . . . . . . . . . . . . 22 3.5.10. Rate Limiting . . . . . . . . . . . . . . . . . . 22
3.5.11. Interaction with Packet Salvaging . . . . . . . . 23 3.5.11. Interaction with Packet Salvaging . . . . . . . . 22
4. Conceptual Data Structures 24
4.1. Route Cache . . . . . . . . . . . . . . . . . . . . . . . 24 4. Conceptual Data Structures 23
4.2. Send Buffer . . . . . . . . . . . . . . . . . . . . . . . 27
4.3. Route Request Table . . . . . . . . . . . . . . . . . . . 28
4.4. Gratuitous Route Reply Table . . . . . . . . . . . . . . 29
4.5. Network Interface Queue and Maintenance Buffer . . . . . 30
4.6. Blacklist . . . . . . . . . . . . . . . . . . . . . . . . 31
5. Additional Conceptual Data Structures for Flow State Extension 32 4.1. Route Cache . . . . . . . . . . . . . . . . . . . . . . . 23
4.2. Send Buffer . . . . . . . . . . . . . . . . . . . . . . . 26
4.3. Route Request Table . . . . . . . . . . . . . . . . . . . 27
4.4. Gratuitous Route Reply Table . . . . . . . . . . . . . . 28
4.5. Network Interface Queue and Maintenance Buffer . . . . . 29
4.6. Blacklist . . . . . . . . . . . . . . . . . . . . . . . . 30
5. Additional Conceptual Data Structures for Flow State Extension 31
5.1. Flow Table . . . . . . . . . . . . . . . . . . . . . . . 32 5.1. Flow Table . . . . . . . . . . . . . . . . . . . . . . . 31
5.2. Automatic Route Shortening Table . . . . . . . . . . . . 33 5.2. Automatic Route Shortening Table . . . . . . . . . . . . 32
5.3. Default Flow ID Table . . . . . . . . . . . . . . . . . . 33 5.3. Default Flow ID Table . . . . . . . . . . . . . . . . . . 32
6. DSR Options Header Format 35 6. DSR Options Header Format 34
6.1. Fixed Portion of DSR Options Header . . . . . . . . . . . 36 6.1. Fixed Portion of DSR Options Header . . . . . . . . . . . 35
6.2. Route Request Option . . . . . . . . . . . . . . . . . . 39 6.2. Route Request Option . . . . . . . . . . . . . . . . . . 38
6.3. Route Reply Option . . . . . . . . . . . . . . . . . . . 41 6.3. Route Reply Option . . . . . . . . . . . . . . . . . . . 40
6.4. Route Error Option . . . . . . . . . . . . . . . . . . . 43 6.4. Route Error Option . . . . . . . . . . . . . . . . . . . 42
6.4.1. Node Unreachable Type-Specific Information . . . 45 6.4.1. Node Unreachable Type-Specific Information . . . 44
6.4.2. Flow State Not Supported Type-Specific Information 45 6.4.2. Flow State Not Supported Type-Specific Information 44
6.4.3. Option Not Supported Type-Specific Information . 45 6.4.3. Option Not Supported Type-Specific Information . 44
6.5. Acknowledgement Request Option . . . . . . . . . . . . . 46 6.5. Acknowledgement Request Option . . . . . . . . . . . . . 45
6.6. Acknowledgement Option . . . . . . . . . . . . . . . . . 47 6.6. Acknowledgement Option . . . . . . . . . . . . . . . . . 46
6.7. DSR Source Route Option . . . . . . . . . . . . . . . . . 48 6.7. DSR Source Route Option . . . . . . . . . . . . . . . . . 47
6.8. Pad1 Option . . . . . . . . . . . . . . . . . . . . . . . 50 6.8. Pad1 Option . . . . . . . . . . . . . . . . . . . . . . . 49
6.9. PadN Option . . . . . . . . . . . . . . . . . . . . . . . 51 6.9. PadN Option . . . . . . . . . . . . . . . . . . . . . . . 50
7. Additional Header Formats and Options for Flow State Extension 52 7. Additional Header Formats and Options for Flow State Extension 51
7.1. DSR Flow State Header . . . . . . . . . . . . . . . . . . 53 7.1. DSR Flow State Header . . . . . . . . . . . . . . . . . . 52
7.2. Options and Extensions in DSR Options Header . . . . . . 54 7.2. New Options and Extensions in DSR Options Header . . . . 53
7.2.1. Timeout Option . . . . . . . . . . . . . . . . . 54 7.2.1. Timeout Option . . . . . . . . . . . . . . . . . 53
7.2.2. Destination and Flow ID Option . . . . . . . . . 55 7.2.2. Destination and Flow ID Option . . . . . . . . . 54
7.2.3. New Error Type Value for Unknown Flow . . . . . . 56 7.3. New Error Types for Route Error Option . . . . . . . . . 55
7.2.4. New Error Type Value for Default Flow Unknown . . 57 7.3.1. Unknown Flow Type-Specific Information . . . . . 55
7.2.5. Acknowledgement Request Option 7.3.2. Default Flow Unknown Type-Specific Information . 56
Previous Hop Address Extension . . . . . . 58 7.4. New Acknowledgement Request Option Extension . . . . . . 57
7.4.1. Previous Hop Address Extension . . . . . . . . . 57
8. Detailed Operation 59 8. Detailed Operation 58
8.1. General Packet Processing . . . . . . . . . . . . . . . . 59 8.1. General Packet Processing . . . . . . . . . . . . . . . . 58
8.1.1. Originating a Packet . . . . . . . . . . . . . . 59 8.1.1. Originating a Packet . . . . . . . . . . . . . . 58
8.1.2. Adding a DSR Options Header to a Packet . . . . . 59 8.1.2. Adding a DSR Options Header to a Packet . . . . . 58
8.1.3. Adding a DSR Source Route Option to a Packet . . 60 8.1.3. Adding a DSR Source Route Option to a Packet . . 59
8.1.4. Processing a Received Packet . . . . . . . . . . 61 8.1.4. Processing a Received Packet . . . . . . . . . . 60
8.1.5. Processing a Received DSR Source Route Option . . 63 8.1.5. Processing a Received DSR Source Route Option . . 62
8.1.6. Handling an Unknown DSR Option . . . . . . . . . 65 8.1.6. Handling an Unknown DSR Option . . . . . . . . . 64
8.2. Route Discovery Processing . . . . . . . . . . . . . . . 67 8.2. Route Discovery Processing . . . . . . . . . . . . . . . 66
8.2.1. Originating a Route Request . . . . . . . . . . . 67 8.2.1. Originating a Route Request . . . . . . . . . . . 66
8.2.2. Processing a Received Route Request Option . . . 69 8.2.2. Processing a Received Route Request Option . . . 68
8.2.3. Generating a Route Reply using the Route Cache . 71 8.2.3. Generating a Route Reply using the Route Cache . 70
8.2.4. Originating a Route Reply . . . . . . . . . . . . 73 8.2.4. Originating a Route Reply . . . . . . . . . . . . 72
8.2.5. Processing a Received Route Reply Option . . . . 75 8.2.5. Preventing Route Reply Storms . . . . . . . . . . 74
8.3. Route Maintenance Processing . . . . . . . . . . . . . . 76 8.2.6. Processing a Received Route Reply Option . . . . 75
8.3.1. Using Link-Layer Acknowledgements . . . . . . . . 76 8.3. Route Maintenance Processing . . . . . . . . . . . . . . 77
8.3.2. Using Passive Acknowledgements . . . . . . . . . 77 8.3.1. Using Link-Layer Acknowledgements . . . . . . . . 77
8.3.3. Using Network-Layer Acknowledgements . . . . . . 78 8.3.2. Using Passive Acknowledgements . . . . . . . . . 78
8.3.4. Originating a Route Error . . . . . . . . . . . . 81 8.3.3. Using Network-Layer Acknowledgements . . . . . . 79
8.3.5. Processing a Received Route Error Option . . . . 82 8.3.4. Originating a Route Error . . . . . . . . . . . . 82
8.3.6. Salvaging a Packet . . . . . . . . . . . . . . . 83 8.3.5. Processing a Received Route Error Option . . . . 83
8.4. Multiple Interface Support . . . . . . . . . . . . . . . 85 8.3.6. Salvaging a Packet . . . . . . . . . . . . . . . 84
8.5. Fragmentation and Reassembly . . . . . . . . . . . . . . 86 8.4. Multiple Network Interface Support . . . . . . . . . . . 86
8.6. Flow State Processing . . . . . . . . . . . . . . . . . . 87 8.5. IP Fragmentation and Reassembly . . . . . . . . . . . . . 87
8.6.1. Originating a Packet . . . . . . . . . . . . . . 87 8.6. Flow State Processing . . . . . . . . . . . . . . . . . . 88
8.6.2. Inserting a DSR Flow State Header . . . . . . . . 89 8.6.1. Originating a Packet . . . . . . . . . . . . . . 88
8.6.3. Receiving a Packet . . . . . . . . . . . . . . . 89 8.6.2. Inserting a DSR Flow State Header . . . . . . . . 90
8.6.4. Forwarding a Packet Using Flow IDs . . . . . . . 94 8.6.3. Receiving a Packet . . . . . . . . . . . . . . . 90
8.6.5. Promiscuously Receiving a Packet . . . . . . . . 94 8.6.4. Forwarding a Packet Using Flow IDs . . . . . . . 95
8.6.5. Promiscuously Receiving a Packet . . . . . . . . 95
8.6.6. Operation where the Layer below DSR Decreases 8.6.6. Operation where the Layer below DSR Decreases
the IP TTL Non-Uniformly . . . . . . . . . 95 the IP TTL Non-Uniformly . . . . . . . . . 96
8.6.7. Salvage Interactions with DSR . . . . . . . . . . 95 8.6.7. Salvage Interactions with DSR . . . . . . . . . . 96
9. Protocol Constants and Configuration Variables 96 9. Protocol Constants and Configuration Variables 97
10. IANA Considerations 97 10. IANA Considerations 98
11. Security Considerations 98 11. Security Considerations 99
Appendix A. Link-MaxLife Cache Description 99 Appendix A. Link-MaxLife Cache Description 100
Appendix B. Location of DSR in the ISO Network Reference Model 101 Appendix B. Location of DSR in the ISO Network Reference Model 102
Appendix C. Implementation and Evaluation Status 102 Appendix C. Implementation and Evaluation Status 103
Changes from Previous Version of the Draft 104 Changes from Previous Version of the Draft 105
Acknowledgements 105 Acknowledgements 106
References 106 References 107
Chair's Address 110 Chair's Address 111
Authors' Addresses 111 Authors' Addresses 112
1. Introduction 1. Introduction
The Dynamic Source Routing protocol (DSR) [15, 16] is a simple and The Dynamic Source Routing protocol (DSR) [15, 16] is a simple and
efficient routing protocol designed specifically for use in multi-hop efficient routing protocol designed specifically for use in multi-hop
wireless ad hoc networks of mobile nodes. Using DSR, the network wireless ad hoc networks of mobile nodes. Using DSR, the network
is completely self-organizing and self-configuring, requiring no is completely self-organizing and self-configuring, requiring no
existing network infrastructure or administration. Network nodes existing network infrastructure or administration. Network nodes
cooperate to forward packets for each other to allow communication cooperate to forward packets for each other to allow communication
over multiple "hops" between nodes not directly within wireless over multiple "hops" between nodes not directly within wireless
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cached route if the one it has been using should fail. This caching cached route if the one it has been using should fail. This caching
of multiple routes also avoids the overhead of needing to perform a of multiple routes also avoids the overhead of needing to perform a
new Route Discovery each time a route in use breaks. The sender of new Route Discovery each time a route in use breaks. The sender of
a packet selects and controls the route used for its own packets, a packet selects and controls the route used for its own packets,
which together with support for multiple routes also allows features which together with support for multiple routes also allows features
such as load balancing to be defined. In addition, all routes used such as load balancing to be defined. In addition, all routes used
are easily guaranteed to be loop-free, since the sender can avoid are easily guaranteed to be loop-free, since the sender can avoid
duplicate hops in the routes selected. duplicate hops in the routes selected.
The operation of both Route Discovery and Route Maintenance in DSR The operation of both Route Discovery and Route Maintenance in DSR
are designed to allow unidirectional links and asymmetric routes are designed to allow unidirectional links and asymmetric routes to
to be easily supported. In particular, as noted in Section 2, in be supported. In particular, as noted in Section 2, in wireless
wireless networks, it is possible that a link between two nodes may networks, it is possible that a link between two nodes may not
not work equally well in both directions, due to differing antenna work equally well in both directions, due to differing antenna or
or propagation patterns or sources of interference. DSR allows such propagation patterns or sources of interference.
unidirectional links to be used when necessary, improving overall
performance and network connectivity in the system.
This document specifies the operation of the DSR protocol for This document specifies the operation of the DSR protocol for
routing unicast IPv4 packets in multi-hop wireless ad hoc networks. routing unicast IPv4 packets in multi-hop wireless ad hoc networks.
Advanced, optional features, such as Quality of Service (QoS) support Advanced, optional features, such as Quality of Service (QoS) support
and efficient multicast routing, and operation of DSR with IPv6 [7], and efficient multicast routing, and operation of DSR with IPv6 [7],
are covered in other documents. The specification of DSR in this are covered in other documents. The specification of DSR in this
document provides a compatible base on which such features can be document provides a compatible base on which such features can be
added, either independently or by integration with the DSR operation added, either independently or by integration with the DSR operation
specified here. specified here.
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receive mode, or can be programmed to only periodically switch the receive mode, or can be programmed to only periodically switch the
interface into promiscuous mode. Use of promiscuous receive mode is interface into promiscuous mode. Use of promiscuous receive mode is
entirely optional. entirely optional.
Wireless communication ability between any pair of nodes may at Wireless communication ability between any pair of nodes may at
times not work equally well in both directions, due for example to times not work equally well in both directions, due for example to
differing antenna or propagation patterns or sources of interference differing antenna or propagation patterns or sources of interference
around the two nodes [1, 20]. That is, wireless communications around the two nodes [1, 20]. That is, wireless communications
between each pair of nodes will in many cases be able to operate between each pair of nodes will in many cases be able to operate
bidirectionally, but at times the wireless link between two nodes bidirectionally, but at times the wireless link between two nodes
may be only unidirectional, allowing one node to successfully send may be only unidirectional, allowing one node to successfully
packets to the other while no communication is possible in the send packets to the other while no communication is possible
reverse direction. Although many routing protocols operate correctly in the reverse direction. Some MAC protocols, however, such as
only over bidirectional links, DSR can successfully discover and MACA [19], MACAW [2], or IEEE 802.11 [13], limit unicast data
forward packets over paths that contain unidirectional links. Some packet transmission to bidirectional links, due to the required
MAC protocols, however, such as MACA [19], MACAW [2], or IEEE bidirectional exchange of RTS and CTS packets in these protocols and
802.11 [13], limit unicast data packet transmission to bidirectional due to the link-layer acknowledgement feature in IEEE 802.11; when
links, due to the required bidirectional exchange of RTS and CTS used on top of MAC protocols such as these, DSR can take advantage
packets in these protocols and due to the link-layer acknowledgement of additional optimizations, such as the ability to reverse a source
feature in IEEE 802.11; when used on top of MAC protocols such as route to obtain a route back to the origin of the original route.
these, DSR can take advantage of additional optimizations, such as
the ability to reverse a source route to obtain a route back to the
origin of the original route.
The IP address used by a node using the DSR protocol MAY be assigned The IP address used by a node using the DSR protocol MAY be assigned
by any mechanism (e.g., static assignment or use of DHCP for dynamic by any mechanism (e.g., static assignment or use of DHCP for dynamic
assignment [8]), although the method of such assignment is outside assignment [8]), although the method of such assignment is outside
the scope of this specification. the scope of this specification.
A routing protocol such as DSR chooses a next-hop for each packet
and provides the IP address of that next-hop. When the packet
is transmitted, however, the lower-layer protocol often has a
separate, MAC-layer address for the next-hop node. DSR uses the
Address Resolution Protocol (ARP) [30] to translate from next-hop IP
addresses to next-hop MAC addresses. In addition, a node MAY add
an entry to its ARP cache based on any received packet, when the IP
address and MAC address of the transmitting node are available in
the packet; for example, the IP address of the transmitting node
is present in a Route Request option (in the Address list being
accumulated) and any packets containing a source route. Adding
entries to the ARP cache in this way avoids the overhead of ARP in
most cases.
3. DSR Protocol Overview 3. DSR Protocol Overview
This section provides an overview of the operation of the DSR This section provides an overview of the operation of the DSR
protocol. The basic version of DSR uses explicit "source routing", protocol. The basic version of DSR uses explicit "source routing",
in which each data packet sent carries in its header the complete, in which each data packet sent carries in its header the complete,
ordered list of nodes through which the packet will pass. This use ordered list of nodes through which the packet will pass. This use
of explicit source routing allows the sender to select and control of explicit source routing allows the sender to select and control
the routes used for its own packets, supports the use of multiple the routes used for its own packets, supports the use of multiple
routes to any destination (for example, for load balancing), and routes to any destination (for example, for load balancing), and
allows a simple guarantee that the routes used are loop-free; by allows a simple guarantee that the routes used are loop-free; by
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a "Route Reply" to the initiator of the Route Discovery, giving a "Route Reply" to the initiator of the Route Discovery, giving
a copy of the accumulated route record from the Route Request; a copy of the accumulated route record from the Route Request;
when the initiator receives this Route Reply, it caches this route when the initiator receives this Route Reply, it caches this route
in its Route Cache for use in sending subsequent packets to this in its Route Cache for use in sending subsequent packets to this
destination. destination.
Otherwise, if this node receiving the Route Request has recently seen Otherwise, if this node receiving the Route Request has recently seen
another Route Request message from this initiator bearing this same another Route Request message from this initiator bearing this same
request identification and target address, or if this node's own request identification and target address, or if this node's own
address is already listed in the route record in the Route Request, address is already listed in the route record in the Route Request,
this node discards the Request. Otherwise, this node appends its this node discards the Request. (A node considers a Request recently
own address to the route record in the Route Request and propagates seen if it still has information about that Request in its Route
it by transmitting it as a local broadcast packet (with the same Request Table, which is described in Section 4.3.) Otherwise, this
request identification). In this example, node B broadcast the Route node appends its own address to the route record in the Route Request
Request, which is received by node C; nodes C and D each also, in and propagates it by transmitting it as a local broadcast packet
turn, broadcast the Request, resulting in a copy of the Request being (with the same request identification). In this example, node B
received by node E. broadcast the Route Request, which is received by node C; nodes C
and D each also, in turn, broadcast the Request, resulting in a copy
of the Request being received by node E.
In returning the Route Reply to the initiator of the Route Discovery, In returning the Route Reply to the initiator of the Route Discovery,
such as in this example, node E replying back to node A, node E will such as in this example, node E replying back to node A, node E will
typically examine its own Route Cache for a route back to A, and if typically examine its own Route Cache for a route back to A, and if
found, will use it for the source route for delivery of the packet found, will use it for the source route for delivery of the packet
containing the Route Reply. Otherwise, E SHOULD perform its own containing the Route Reply. Otherwise, E SHOULD perform its own
Route Discovery for target node A, but to avoid possible infinite Route Discovery for target node A, but to avoid possible infinite
recursion of Route Discoveries, it MUST piggyback this Route Reply recursion of Route Discoveries, it MUST piggyback this Route Reply
on the packet containing its own Route Request for A. It is also on the packet containing its own Route Request for A. It is also
possible to piggyback other small data packets, such as a TCP SYN possible to piggyback other small data packets, such as a TCP SYN
packet [31], on a Route Request using this same mechanism. packet [33], on a Route Request using this same mechanism.
Node E could instead simply reverse the sequence of hops in the route Node E could instead simply reverse the sequence of hops in the route
record that it is trying to send in the Route Reply, and use this as record that it is trying to send in the Route Reply, and use this as
the source route on the packet carrying the Route Reply itself. For the source route on the packet carrying the Route Reply itself. For
MAC protocols such as IEEE 802.11 that require a bidirectional frame MAC protocols such as IEEE 802.11 that require a bidirectional frame
exchange as part of the MAC protocol [13], the discovered source exchange as part of the MAC protocol [13], the discovered source
route MUST be reversed in this way to return the Route Reply since it route MUST be reversed in this way to return the Route Reply since it
tests the discovered route to ensure it is bidirectional before the tests the discovered route to ensure it is bidirectional before the
Route Discovery initiator begins using the route; this route reversal Route Discovery initiator begins using the route; this route reversal
also avoids the overhead of a possible second Route Discovery. also avoids the overhead of a possible second Route Discovery.
However, this route reversal technique will prevent the discovery of
routes using unidirectional links, and in wireless environments where
the use of unidirectional links is permitted, such routes may in some
cases be more efficient than those with only bidirectional links, or
they may be the only way to achieve connectivity to the target node.
When initiating a Route Discovery, the sending node saves a copy of When initiating a Route Discovery, the sending node saves a copy of
the original packet (that triggered the Discovery) in a local buffer the original packet (that triggered the Discovery) in a local buffer
called the "Send Buffer". The Send Buffer contains a copy of each called the "Send Buffer". The Send Buffer contains a copy of each
packet that cannot be transmitted by this node because it does not packet that cannot be transmitted by this node because it does not
yet have a source route to the packet's destination. Each packet in yet have a source route to the packet's destination. Each packet in
the Send Buffer is logically associated with the time that it was the Send Buffer is logically associated with the time that it was
placed into the Send Buffer and is discarded after residing in the placed into the Send Buffer and is discarded after residing in the
Send Buffer for some timeout period; if necessary for preventing the Send Buffer for some timeout period SendBufferTimeout; if necessary
Send Buffer from overflowing, a FIFO or other replacement strategy for preventing the Send Buffer from overflowing, a FIFO or other
MAY also be used to evict packets even before they expire. replacement strategy MAY also be used to evict packets even before
they expire.
While a packet remains in the Send Buffer, the node SHOULD While a packet remains in the Send Buffer, the node SHOULD
occasionally initiate a new Route Discovery for the packet's occasionally initiate a new Route Discovery for the packet's
destination address. However, the node MUST limit the rate at which destination address. However, the node MUST limit the rate at which
such new Route Discoveries for the same address are initiated, since such new Route Discoveries for the same address are initiated (as
it is possible that the destination node is not currently reachable. described in Section 4.3), since it is possible that the destination
In particular, due to the limited wireless transmission range and the node is not currently reachable. In particular, due to the limited
movement of the nodes in the network, the network may at times become wireless transmission range and the movement of the nodes in the
partitioned, meaning that there is currently no sequence of nodes network, the network may at times become partitioned, meaning that
through which a packet could be forwarded to reach the destination. there is currently no sequence of nodes through which a packet could
Depending on the movement pattern and the density of nodes in the be forwarded to reach the destination. Depending on the movement
network, such network partitions may be rare or may be common. pattern and the density of nodes in the network, such network
partitions may be rare or may be common.
If a new Route Discovery was initiated for each packet sent by a If a new Route Discovery was initiated for each packet sent by a
node in such a partitioned network, a large number of unproductive node in such a partitioned network, a large number of unproductive
Route Request packets would be propagated throughout the subset Route Request packets would be propagated throughout the subset
of the ad hoc network reachable from this node. In order to of the ad hoc network reachable from this node. In order to
reduce the overhead from such Route Discoveries, a node SHOULD use reduce the overhead from such Route Discoveries, a node SHOULD use
an exponential back-off algorithm to limit the rate at which it an exponential back-off algorithm to limit the rate at which it
initiates new Route Discoveries for the same target, doubling the initiates new Route Discoveries for the same target, doubling the
timeout between each successive Discovery initiated for the same timeout between each successive Discovery initiated for the same
target. If the node attempts to send additional data packets to this target. If the node attempts to send additional data packets to this
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protocol in use (such as the link-layer acknowledgement frame defined protocol in use (such as the link-layer acknowledgement frame defined
by IEEE 802.11 [13]), or by a "passive acknowledgement" [18] (in by IEEE 802.11 [13]), or by a "passive acknowledgement" [18] (in
which, for example, B confirms receipt at C by overhearing C transmit which, for example, B confirms receipt at C by overhearing C transmit
the packet when forwarding it on to D). the packet when forwarding it on to D).
If a built-in acknowledgement mechanism is not available, the If a built-in acknowledgement mechanism is not available, the
node transmitting the packet can explicitly request a DSR-specific node transmitting the packet can explicitly request a DSR-specific
software acknowledgement be returned by the next node along the software acknowledgement be returned by the next node along the
route; this software acknowledgement will normally be transmitted route; this software acknowledgement will normally be transmitted
directly to the sending node, but if the link between these two nodes directly to the sending node, but if the link between these two nodes
is unidirectional, this software acknowledgement could travel over a is unidirectional (Section 4.6), this software acknowledgement could
different, multi-hop path. travel over a different, multi-hop path.
After an acknowledgement has been received from some neighbor, a node After an acknowledgement has been received from some neighbor, a node
MAY choose to not require acknowledgements from that neighbor for a MAY choose to not require acknowledgements from that neighbor for a
brief period of time, unless the network interface connecting a node brief period of time, unless the network interface connecting a node
to that neighbor always receives an acknowledgement in response to to that neighbor always receives an acknowledgement in response to
unicast traffic. unicast traffic.
When a software acknowledgement is used, the acknowledgement When a software acknowledgement is used, the acknowledgement
request SHOULD be retransmitted up to a maximum number of times. request SHOULD be retransmitted up to a maximum number of times.
A retransmission of the acknowledgement request can be sent as a A retransmission of the acknowledgement request can be sent as a
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means that a future Route Error traversing the route is very likely means that a future Route Error traversing the route is very likely
to pass through any node that sent the Route Reply for the route to pass through any node that sent the Route Reply for the route
(including node F), which helps to ensure that stale data is removed (including node F), which helps to ensure that stale data is removed
from caches (such as at F) in a timely manner; otherwise, the next from caches (such as at F) in a timely manner; otherwise, the next
Route Discovery initiated by A might also be contaminated by a Route Route Discovery initiated by A might also be contaminated by a Route
Reply from F containing the same stale route. If node F, due to this Reply from F containing the same stale route. If node F, due to this
restriction on returning a Route Reply based on information from its restriction on returning a Route Reply based on information from its
Route Cache, does not return such a Route Reply, node F propagates Route Cache, does not return such a Route Reply, node F propagates
the Route Request normally. the Route Request normally.
3.3.3. Preventing Route Reply Storms 3.3.3. Route Request Hop Limits
The ability for nodes to reply to a Route Request based on
information in their Route Caches, as described in Section 3.3.2,
could result in a possible Route Reply "storm" in some cases. In
particular, if a node broadcasts a Route Request for a target node
for which the node's neighbors have a route in their Route Caches,
each neighbor may attempt to send a Route Reply, thereby wasting
bandwidth and possibly increasing the number of network collisions in
the area.
For example, the figure below shows a situation in which nodes B, C,
D, E, and F all receive A's Route Request for target G, and each has
the indicated route cached for this target:
+-----+ +-----+
| D |< >| C |
+-----+ \ / +-----+
Cache: C - B - G \ / Cache: B - G
\ +-----+ /
-| A |-
+-----+\ +-----+ +-----+
| | \--->| B | | G |
/ \ +-----+ +-----+
/ \ Cache: G
v v
+-----+ +-----+
| E | | F |
+-----+ +-----+
Cache: F - B - G Cache: B - G
Normally, each of these nodes would attempt to reply from its own
Route Cache, and they would thus all send their Route Replies at
about the same time, since they all received the broadcast Route
Request at about the same time. Such simultaneous Route Replies
from different nodes all receiving the Route Request may cause local
congestion in the wireless network and may create packet collisions
among some or all of these Replies if the MAC protocol in use does
not provide sufficient collision avoidance for these packets. In
addition, it will often be the case that the different replies will
indicate routes of different lengths, as shown in this example.
In order to reduce these effects, if a node can put its network
interface into promiscuous receive mode, it MAY delay sending its
own Route Reply for a short period, while listening to see if the
initiating node begins using a shorter route first. Specifically,
this node MAY delay sending its own Route Reply for a random period
d = H * (h - 1 + r)
where h is the length in number of network hops for the route to be
returned in this node's Route Reply, r is a random floating point
number between 0 and 1, and H is a small constant delay (at least
twice the maximum wireless link propagation delay) to be introduced
per hop. This delay effectively randomizes the time at which each
node sends its Route Reply, with all nodes sending Route Replies
giving routes of length less than h sending their Replies before this
node, and all nodes sending Route Replies giving routes of length
greater than h sending their Replies after this node.
Within the delay period, this node promiscuously receives all
packets, looking for data packets from the initiator of this Route
Discovery destined for the target of the Discovery. If such a data
packet received by this node during the delay period uses a source
route of length less than or equal to h, this node may infer that the
initiator of the Route Discovery has already received a Route Reply
giving an equally good or better route. In this case, this node
SHOULD cancel its delay timer and SHOULD NOT send its Route Reply for
this Route Discovery.
3.3.4. Route Request Hop Limits
Each Route Request message contains a "hop limit" that may be used Each Route Request message contains a "hop limit" that may be used
to limit the number of intermediate nodes allowed to forward that to limit the number of intermediate nodes allowed to forward that
copy of the Route Request. This hop limit is implemented using the copy of the Route Request. This hop limit is implemented using the
Time-to-Live (TTL) field in the IP header of the packet carrying Time-to-Live (TTL) field in the IP header of the packet carrying
the Route Request. As the Request is forwarded, this limit is the Route Request. As the Request is forwarded, this limit is
decremented, and the Request packet is discarded if the limit reaches decremented, and the Request packet is discarded if the limit reaches
zero before finding the target. This Route Request hop limit can be zero before finding the target. This Route Request hop limit can be
used to implement a variety of algorithms for controlling the spread used to implement a variety of algorithms for controlling the spread
of a Route Request during a Route Discovery attempt. of a Route Request during a Route Discovery attempt.
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"non-propagating" Route Request as an initial phase of a Route "non-propagating" Route Request as an initial phase of a Route
Discovery. A node using this technique sends its first Route Request Discovery. A node using this technique sends its first Route Request
attempt for some target node using a hop limit of 1, such that any attempt for some target node using a hop limit of 1, such that any
node receiving the initial transmission of the Route Request will node receiving the initial transmission of the Route Request will
not forward the Request to other nodes by re-broadcasting it. This not forward the Request to other nodes by re-broadcasting it. This
form of Route Request is called a "non-propagating" Route Request; form of Route Request is called a "non-propagating" Route Request;
it provides an inexpensive method for determining if the target is it provides an inexpensive method for determining if the target is
currently a neighbor of the initiator or if a neighbor node has a currently a neighbor of the initiator or if a neighbor node has a
route to the target cached (effectively using the neighbors' Route route to the target cached (effectively using the neighbors' Route
Caches as an extension of the initiator's own Route Cache). If no Caches as an extension of the initiator's own Route Cache). If no
Route Reply is received after a short timeout, then the node sends a Route Reply is received after a short timeout, then the node sends
"propagating" Route Request (i.e., with no hop limit) for the target a "propagating" Route Request for the target node (i.e., with hop
node. limit as defined by the value of the DiscoveryHopLimit configuration
variable).
As another example, a node MAY use this hop limit to implement an As another example, a node MAY use this hop limit to implement an
"expanding ring" search for the target [16]. A node using this "expanding ring" search for the target [16]. A node using this
technique sends an initial non-propagating Route Request as described technique sends an initial non-propagating Route Request as described
above; if no Route Reply is received for it, the node originates above; if no Route Reply is received for it, the node originates
another Route Request with a hop limit of 2. For each Route Request another Route Request with a hop limit of 2. For each Route Request
originated, if no Route Reply is received for it, the node doubles originated, if no Route Reply is received for it, the node doubles
the hop limit used on the previous attempt, to progressively explore the hop limit used on the previous attempt, to progressively explore
for the target node without allowing the Route Request to propagate for the target node without allowing the Route Request to propagate
over the entire network. However, this expanding ring search over the entire network. However, this expanding ring search
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source route on the packet with the route from its Route Cache. The source route on the packet with the route from its Route Cache. The
node then forwards the packet to the next node indicated along this node then forwards the packet to the next node indicated along this
source route. For example, in the situation shown in the example of source route. For example, in the situation shown in the example of
Section 3.2, if node C has another route cached to node E, it can Section 3.2, if node C has another route cached to node E, it can
salvage the packet by replacing the original route in the packet with salvage the packet by replacing the original route in the packet with
this new route from its own Route Cache, rather than discarding the this new route from its own Route Cache, rather than discarding the
packet. packet.
When salvaging a packet, a count is maintained in the packet of the When salvaging a packet, a count is maintained in the packet of the
number of times that it has been salvaged, to prevent a single packet number of times that it has been salvaged, to prevent a single packet
from being salvaged endlessly. Otherwise, it could be possible for from being salvaged endlessly. Otherwise, since TTL is decremented
the packet to enter a routing loop, as different nodes repeatedly only once by each node, a single node could salvage a packet an
salvage the packet and replace the source route on the packet with unbounded number of times. Even if we chose to require TTL to be
routes to each other. decremented on each salvage attempt, packet salvaging is an expensive
operation, so it is desirable to bound the maximum number of times a
packet can be salvaged independently of the maximum number of hops a
packet can traverse.
As described in Section 3.2, an intermediate node, such as in this As described in Section 3.2, an intermediate node, such as in this
case, that detects through Route Maintenance that the next hop along case, that detects through Route Maintenance that the next hop along
the route for a packet that it is forwarding is broken, the node also the route for a packet that it is forwarding is broken, the node also
SHOULD return a Route Error to the original sender of the packet, SHOULD return a Route Error to the original sender of the packet,
identifying the link over which the packet could not be forwarded. identifying the link over which the packet could not be forwarded.
If the node sends this Route Error, it SHOULD originate the Route If the node sends this Route Error, it SHOULD originate the Route
Error before salvaging the packet. Error before salvaging the packet.
3.4.2. Queued Packets Destined over a Broken Link 3.4.2. Queued Packets Destined over a Broken Link
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overheard packet (node B), plus the suffix of the original source overheard packet (node B), plus the suffix of the original source
route beginning with the node returning the gratuitous Route Reply route beginning with the node returning the gratuitous Route Reply
(node D). In this example, the route returned in the gratuitous Route (node D). In this example, the route returned in the gratuitous Route
Reply message sent from D to A gives the new route as the sequence of Reply message sent from D to A gives the new route as the sequence of
hops from A to B to D to E. hops from A to B to D to E.
When deciding whether to return a gratuitous Route Reply in this way, When deciding whether to return a gratuitous Route Reply in this way,
a node MAY factor in additional information beyond the fact that it a node MAY factor in additional information beyond the fact that it
was able to overhear the packet. For example, the node MAY decide to was able to overhear the packet. For example, the node MAY decide to
return the gratuitous Route Reply only when the overheard packet is return the gratuitous Route Reply only when the overheard packet is
received with a signal strenth or signal-to-noise ratio above some received with a signal strength or signal-to-noise ratio above some
specific threshold. In addition, each node maintains a Gratuitous specific threshold. In addition, each node maintains a Gratuitous
Route Reply Table, as described in Section 4.4, to limit the rate at Route Reply Table, as described in Section 4.4, to limit the rate at
which it originates gratuitous Route Replies for the same returned which it originates gratuitous Route Replies for the same returned
route. route.
3.4.4. Increased Spreading of Route Error Messages 3.4.4. Increased Spreading of Route Error Messages
When a source node receives a Route Error for a data packet that When a source node receives a Route Error for a data packet that
it originated, this source node propagates this Route Error to its it originated, this source node propagates this Route Error to its
neighbors by piggybacking it on its next Route Request. In this way, neighbors by piggybacking it on its next Route Request. In this way,
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DSR Options header, giving the lifetime after which state information DSR Options header, giving the lifetime after which state information
about this flow is to expire. This packet will generally be a normal about this flow is to expire. This packet will generally be a normal
data packet being sent from this sender to the receiver (for example, data packet being sent from this sender to the receiver (for example,
the first packet sent after discovering the new route) but is also the first packet sent after discovering the new route) but is also
treated as a "flow establishment" packet. treated as a "flow establishment" packet.
The source node records this flow in its Flow Table for future use, The source node records this flow in its Flow Table for future use,
setting the TTL in this Flow Table entry to be the value used in the setting the TTL in this Flow Table entry to be the value used in the
TTL field in the packet's IP header and setting the Lifetime in this TTL field in the packet's IP header and setting the Lifetime in this
entry to be the lifetime specified in the Timeout option in the DSR entry to be the lifetime specified in the Timeout option in the DSR
Options header. Options header. The TTL field is used for Default Flow Forwarding,
as described in Sections 3.5.3 and 3.5.4.
Any further packets sent with this flow ID before the timeout that Any further packets sent with this flow ID before the timeout that
also contain a DSR Options header with a Source Route option MUST use also contain a DSR Options header with a Source Route option MUST use
this same source route in the Source Route option. this same source route in the Source Route option.
3.5.2. Receiving and Forwarding Establishment Packets 3.5.2. Receiving and Forwarding Establishment Packets
Packets intended to establish a flow, as described in Section 3.5.1, Packets intended to establish a flow, as described in Section 3.5.1,
contain a DSR Options header with a Source Route option, and are contain a DSR Options header with a Source Route option, and are
forwarded along the indicated route. A node implementing the DSR forwarded along the indicated route. A node implementing the DSR
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the flow to indicate that it has not been established end-to-end. the flow to indicate that it has not been established end-to-end.
When a node receives a Route Error of type Default Flow Unknown, it When a node receives a Route Error of type Default Flow Unknown, it
marks the default flow to indicate that it has not been established marks the default flow to indicate that it has not been established
end-to-end. end-to-end.
3.5.6. Interaction with Automatic Route Shortening 3.5.6. Interaction with Automatic Route Shortening
Because a full source route is not carried in every packet, an Because a full source route is not carried in every packet, an
alternative method for performing automatic route shortening is alternative method for performing automatic route shortening is
necessary for packets using the flow state extension. Instead, nodes necessary for packets using the flow state extension. Instead, nodes
promiscuously listen to packets, and if a node receives a packet promiscuously listen to packets, and if a node receives a packet with
with (IP Source, IP Destination, Flow ID) found in the Flow Table (IP Source, IP Destination, Flow ID) found in the Flow Table but the
but the MAC-layer (next hop) destination address of the packet is MAC-layer (next hop) destination address of the packet is not this
not this node, the node determines whether the packet was sent by node, the node determines whether the packet was sent by an upstream
an upstream or downstream node by examining the Hop Count field in or downstream node by examining the Hop Count field in the DSR Flow
the DSR Flow State header. If the Hop Count field is less than the State header. If the Hop Count field is less than the expected
expected Hop Count at this node, the node assumes that the packet Hop Count at this node (that is, the expected Hop Count field in
was sent by an upstream node, and adds an entry for the packet to the Flow Table described in Section 5.1), the node assumes that the
its Automatic Route Shortening Table, possibly evicting an earlier packet was sent by an upstream node, and adds an entry for the packet
to its Automatic Route Shortening Table, possibly evicting an earlier
entry added to this table. When the packet is then sent to that node entry added to this table. When the packet is then sent to that node
for forwarding, the node finds that it has previously received the for forwarding, the node finds that it has previously received the
packet by checking its Automatic Route Shortening Table, and returns packet by checking its Automatic Route Shortening Table, and returns
a gratuitous Route Reply to the source of the packet. a gratuitous Route Reply to the source of the packet.
3.5.7. Loop Detection 3.5.7. Loop Detection
If a node receives a packet for forwarding with adjusted TTL lower If a node receives a packet for forwarding with TTL lower than
than expected and default flow forwarding is being used, it sends expected and default flow forwarding is being used, it sends a
a Route Error of type Default Flow Unknown back to the IP source. Route Error of type Default Flow Unknown back to the IP source. It
It can attempt delivery of the packet by normal salvaging (subject can attempt delivery of the packet by normal salvaging (subject
to constraints described in Section 8.6.7) or by inserting a to constraints described in Section 8.6.7) or by inserting a
Flow ID option with Special TTL extension based on what that node's Flow ID option with Special TTL extension based on what that node's
understanding of the default Flow ID and TTL. understanding of the default Flow ID and TTL.
3.5.8. Acknowledgement Destination 3.5.8. Acknowledgement Destination
In packets sent using Flow State, the previous hop is not necessarily In packets sent using Flow State, the previous hop is not necessarily
known. In order to allow nodes that have lost flow state to known. In order to allow nodes that have lost flow state to
determine the previous hop, the address of the previous hop can determine the previous hop, the address of the previous hop can
optionally be stored in the Acknowledgement Request. This extension optionally be stored in the Acknowledgement Request. This extension
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in a DSR Options header, packets without a Source Route option are in a DSR Options header, packets without a Source Route option are
considered to have the value zero in the Salvage field. considered to have the value zero in the Salvage field.
4. Conceptual Data Structures 4. Conceptual Data Structures
This document describes the operation of the DSR protocol in terms This document describes the operation of the DSR protocol in terms
of a number of conceptual data structures. This section describes of a number of conceptual data structures. This section describes
each of these data structures and provides an overview of its use each of these data structures and provides an overview of its use
in the protocol. In an implementation of the protocol, these data in the protocol. In an implementation of the protocol, these data
structures MAY be implemented in any manner consistent with the structures MAY be implemented in any manner consistent with the
external behavior described in this document. external behavior described in this document. Additional conceptual
data structures are required for the optional flow state extensions
to DSR; these data structures are described in Section 5.
4.1. Route Cache 4.1. Route Cache
All ad hoc network routing information needed by a node implementing Each node implementing DSR MUST maintain a Route Cache, containing
DSR is stored in that node's Route Cache. Each node in the network routing information needed by the node. A node adds information to
maintains its own Route Cache. A node adds information to its its Route Cache as it learns of new links between nodes in the ad hoc
Route Cache as it learns of new links between nodes in the ad hoc
network; for example, a node may learn of new links when it receives network; for example, a node may learn of new links when it receives
a packet carrying a Route Request, Route Reply, or DSR source route. a packet carrying a Route Request, Route Reply, or DSR source route.
Likewise, a node removes information from its Route Cache as it Likewise, a node removes information from its Route Cache as it
learns that existing links in the ad hoc network have broken; for learns that existing links in the ad hoc network have broken; for
example, a node may learn of a broken link when it receives a packet example, a node may learn of a broken link when it receives a packet
carrying a Route Error or through the link-layer retransmission carrying a Route Error or through the link-layer retransmission
mechanism reporting a failure in forwarding a packet to its next-hop mechanism reporting a failure in forwarding a packet to its next-hop
destination. destination.
Anytime a node adds new information to its Route Cache, the node Anytime a node adds new information to its Route Cache, the node
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The Send Buffer of a node implementing DSR is a queue of packets that The Send Buffer of a node implementing DSR is a queue of packets that
cannot be sent by that node because it does not yet have a source cannot be sent by that node because it does not yet have a source
route to each such packet's destination. Each packet in the Send route to each such packet's destination. Each packet in the Send
Buffer is logically associated with the time that it was placed into Buffer is logically associated with the time that it was placed into
the Buffer, and SHOULD be removed from the Send Buffer and silently the Buffer, and SHOULD be removed from the Send Buffer and silently
discarded after a period of SendBufferTimeout after initially being discarded after a period of SendBufferTimeout after initially being
placed in the Buffer. If necessary, a FIFO strategy SHOULD be used placed in the Buffer. If necessary, a FIFO strategy SHOULD be used
to evict packets before they timeout to prevent the buffer from to evict packets before they timeout to prevent the buffer from
overflowing. overflowing.
Subject to the rate limiting defined in Section 8.2, a Route Subject to the rate limiting defined in Section 4.3, a Route
Discovery SHOULD be initiated as often as possible for the Discovery SHOULD be initiated as often as possible for the
destination address of any packets residing in the Send Buffer. destination address of any packets residing in the Send Buffer.
4.3. Route Request Table 4.3. Route Request Table
The Route Request Table of a node implementing DSR records The Route Request Table of a node implementing DSR records
information about Route Requests that have been recently originated information about Route Requests that have been recently originated
or forwarded by this node. The table is indexed by IP address. or forwarded by this node. The table is indexed by IP address.
The Route Request Table on a node records the following information The Route Request Table on a node records the following information
about nodes to which this node has initiated a Route Request: about nodes to which this node has initiated a Route Request:
- The Time-to-Live (TTL) field used in the IP header of the Route - The Time-to-Live (TTL) field used in the IP header of the Route
Request for the last Route Discovery initiated by this node for Request for the last Route Discovery initiated by this node for
that target node. This value allows the node to implement a that target node. This value allows the node to implement a
variety of algorithms for controlling the spread of its Route variety of algorithms for controlling the spread of its Route
Request on each Route Discovery initiated for a target. As Request on each Route Discovery initiated for a target. As
examples, two possible algorithms for this use of the TTL field examples, two possible algorithms for this use of the TTL field
are described in Section 3.3.4. are described in Section 3.3.3.
- The time that this node last originated a Route Request for that - The time that this node last originated a Route Request for that
target node. target node.
- The number of consecutive Route Discoveries initiated for this - The number of consecutive Route Discoveries initiated for this
target since receiving a valid Route Reply giving a route to that target since receiving a valid Route Reply giving a route to that
target node. target node.
- The remaining amount of time before which this node MAY next - The remaining amount of time before which this node MAY next
attempt at a Route Discovery for that target node. When the attempt at a Route Discovery for that target node. When the
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requires limited buffering of packets already transmitted for requires limited buffering of packets already transmitted for
which the reachability of the next-hop destination has not yet been which the reachability of the next-hop destination has not yet been
determined. The operation of DSR is defined here in terms of two determined. The operation of DSR is defined here in terms of two
conceptual data structures that together incorporate this queuing conceptual data structures that together incorporate this queuing
behavior. behavior.
The Network Interface Queue of a node implementing DSR is an output The Network Interface Queue of a node implementing DSR is an output
queue of packets from the network protocol stack waiting to be queue of packets from the network protocol stack waiting to be
transmitted by the network interface; for example, in the 4.4BSD transmitted by the network interface; for example, in the 4.4BSD
Unix network protocol stack implementation, this queue for a network Unix network protocol stack implementation, this queue for a network
interface is represented as a "struct ifqueue" [36]. This queue is interface is represented as a "struct ifqueue" [38]. This queue is
used to hold packets while the network interface is in the process of used to hold packets while the network interface is in the process of
transmitting another packet. transmitting another packet.
The Maintenance Buffer of a node implementing DSR is a queue of The Maintenance Buffer of a node implementing DSR is a queue of
packets sent by this node that are awaiting next-hop reachability packets sent by this node that are awaiting next-hop reachability
confirmation as part of Route Maintenance. For each packet in confirmation as part of Route Maintenance. For each packet in
the Maintenance Buffer, a node maintains a count of the number the Maintenance Buffer, a node maintains a count of the number
of retransmissions and the time of the last retransmission. The of retransmissions and the time of the last retransmission. The
Maintenance Buffer MAY be of limited size; when adding a new packet Maintenance Buffer MAY be of limited size; when adding a new packet
to the Maintenance Buffer, if the buffer size is insufficient to hold to the Maintenance Buffer, if the buffer size is insufficient to hold
skipping to change at page 31, line 11 skipping to change at page 30, line 11
that might be attempted for a packet at the link layer or within that might be attempted for a packet at the link layer or within
the network interface hardware. The timeout value to use for each the network interface hardware. The timeout value to use for each
transmission attempt for an acknowledgement request depends on the transmission attempt for an acknowledgement request depends on the
type of acknowledgement mechanism used by Route Maintenance for that type of acknowledgement mechanism used by Route Maintenance for that
attempt, as described in Section 8.3. attempt, as described in Section 8.3.
4.6. Blacklist 4.6. Blacklist
When a node using the DSR protocol is connected through an When a node using the DSR protocol is connected through an
interface that requires physically bidirectional links for unicast interface that requires physically bidirectional links for unicast
transmission, it MUST maintain a blacklist. A Blacklist is a table, transmission, it MUST maintain a Blacklist. The Blacklist is a
indexed by neighbor address, that indicates that the link between table, indexed by neighbor node address, that indicates that the
this node and the specified neighbor may not be bidirectional. A link between this node and the specified neighbor node may not be
node places another node's address in this list when it believes that bidirectional. A node places another node's address in this list
broadcast packets from that other node reach this node, but that when it believes that broadcast packets from that other node reach
unicast transmission between the two nodes is not possible. For this node, but that unicast transmission between the two nodes is not
example, if a node forwarding a Route Reply discovers that the next possible. For example, if a node forwarding a Route Reply discovers
hop is unreachable, it places that next hop in the node's blacklist. that the next hop is unreachable, it places that next hop in the
node's Blacklist.
Once a node discovers that it can communicate bidirectionally with Once a node discovers that it can communicate bidirectionally with
one of the nodes listed in the blacklist, it SHOULD remove that one of the nodes listed in the Blacklist, it SHOULD remove that
node from the blacklist. For example, if node A has node B in its node from the Blacklist. For example, if node A has node B listed
blacklist, but A hears B forward a Route Request with a hop list in its Blacklist, but after transmitting a Route Request, node A
indicating that the broadcast from A to B was successful, then A hears B forward the Route Request with a hop list indicating that the
SHOULD remove B from its blacklist. broadcast from A to B was successful, then A SHOULD remove the entry
for node B from its Blacklist.
A node MUST associate a state with each node in the blacklist, A node MUST associate a state with each node listed in its Blacklist,
specifying whether the unidirectionality is "questionable" specifying whether the unidirectionality of the link to that node
or "probable". Each time the unreachability is positively is "questionable" or "probable". Each time the unreachability is
determined, the node SHOULD set the state to "probable". After the positively determined, the node SHOULD set the state to "probable".
unreachability has not been positively determined for some amount of After the unreachability has not been positively determined for some
time, the state should revert to "questionable". A node MAY expire amount of time, the state SHOULD revert to "questionable". A node
nodes from its blacklist after a reasonable amount of time. MAY expire entries for nodes from its Blacklist after a reasonable
amount of time.
5. Additional Conceptual Data Structures for Flow State Extension 5. Additional Conceptual Data Structures for Flow State Extension
This section defines additional conceptual data structures used by This section defines additional conceptual data structures used by
the optional "flow state" extension to DSR. In an implementation of the optional "flow state" extension to DSR. In an implementation of
the protocol, these data structures MAY be implemented in any manner the protocol, these data structures MAY be implemented in any manner
consistent with the external behavior described in this document. consistent with the external behavior described in this document.
5.1. Flow Table 5.1. Flow Table
skipping to change at page 36, line 25 skipping to change at page 35, line 25
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. Options . . Options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header Next Header
8-bit selector. Identifies the type of header immediately 8-bit selector. Identifies the type of header immediately
following the DSR Options header. Uses the same values as the following the DSR Options header. Uses the same values as the
IPv4 Protocol field [32]. IPv4 Protocol field [34].
Flow State Header (F) Flow State Header (F)
Flag bit. MUST be set to 0. This bit is set in a DSR Flow Flag bit. MUST be set to 0. This bit is set in a DSR Flow
State header (Section 7.1) and clear in a DSR Options header. State header (Section 7.1) and clear in a DSR Options header.
Reserved Reserved
MUST be sent as 0 and ignored on reception. MUST be sent as 0 and ignored on reception.
skipping to change at page 39, line 5 skipping to change at page 37, line 24
- Acknowledgement Request option (Section 6.5) - Acknowledgement Request option (Section 6.5)
- Acknowledgement option (Section 6.6) - Acknowledgement option (Section 6.6)
- DSR Source Route option (Section 6.7) - DSR Source Route option (Section 6.7)
- Pad1 option (Section 6.8) - Pad1 option (Section 6.8)
- PadN option (Section 6.9) - PadN option (Section 6.9)
In addition, Section 7 specifies further DSR options for use with the
optional DSR flow state extension.
6.2. Route Request Option 6.2. Route Request Option
The Route Request option in a DSR Options header is encoded as The Route Request option in a DSR Options header is encoded as
follows: follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Opt Data Len | Identification | | Option Type | Opt Data Len | Identification |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 39, line 43 skipping to change at page 38, line 43
Destination Address Destination Address
MUST be set to the IP limited broadcast address MUST be set to the IP limited broadcast address
(255.255.255.255). (255.255.255.255).
Hop Limit (TTL) Hop Limit (TTL)
MAY be varied from 1 to 255, for example to implement MAY be varied from 1 to 255, for example to implement
non-propagating Route Requests and Route Request expanding-ring non-propagating Route Requests and Route Request expanding-ring
searches (Section 3.3.4). searches (Section 3.3.3).
Route Request fields: Route Request fields:
Option Type Option Type
2 1. Nodes not understanding this option will ignore this
option.
Opt Data Len Opt Data Len
8-bit unsigned integer. Length of the option, in octets, 8-bit unsigned integer. Length of the option, in octets,
excluding the Option Type and Opt Data Len fields. excluding the Option Type and Opt Data Len fields.
Identification Identification
A unique value generated by the initiator (original sender) of A unique value generated by the initiator (original sender) of
the Route Request. Nodes initiating a Route Request generate the Route Request. Nodes initiating a Route Request generate
skipping to change at page 41, line 45 skipping to change at page 40, line 45
MUST be set to the address of the source node of the route MUST be set to the address of the source node of the route
being returned. Copied from the Source Address field of the being returned. Copied from the Source Address field of the
Route Request generating the Route Reply, or in the case of a Route Request generating the Route Reply, or in the case of a
gratuitous Route Reply, copied from the Source Address field of gratuitous Route Reply, copied from the Source Address field of
the data packet triggering the gratuitous Reply. the data packet triggering the gratuitous Reply.
Route Reply fields: Route Reply fields:
Option Type Option Type
1. Nodes not understanding this option will ignore this 2. Nodes not understanding this option will ignore this
option. option.
Opt Data Len Opt Data Len
8-bit unsigned integer. Length of the option, in octets, 8-bit unsigned integer. Length of the option, in octets,
excluding the Option Type and Opt Data Len fields. excluding the Option Type and Opt Data Len fields.
Last Hop External (L) Last Hop External (L)
Set to indicate that the last hop given by the Route Reply Set to indicate that the last hop given by the Route Reply
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Options header to make the total length a multiple of 4 octets. Options header to make the total length a multiple of 4 octets.
7. Additional Header Formats and Options for Flow State Extension 7. Additional Header Formats and Options for Flow State Extension
The optional DSR flow state extension requires a new header type, the The optional DSR flow state extension requires a new header type, the
DSR Flow State header. DSR Flow State header.
In addition, the DSR flow state extension adds the following options In addition, the DSR flow state extension adds the following options
for the DSR Options header defined in Section 6: for the DSR Options header defined in Section 6:
- Timeout option - Timeout option (Section 7.2.1
- Destination and Flow ID option - Destination and Flow ID option (Section 7.2.2
Two new Error Type values are also defined for use in the Route Error Two new Error Type values are also defined for use in the Route Error
option in a DSR Options header: option in a DSR Options header:
- Unknown Flow - Unknown Flow
- Default Flow Unknown - Default Flow Unknown
Finally, an extension to the Acknowledgement Request option in a DSR Finally, an extension to the Acknowledgement Request option in a DSR
Options header is also defined: Options header is also defined:
skipping to change at page 53, line 23 skipping to change at page 52, line 23
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Next Header |F| Hop Count | Flow Identifier | | Next Header |F| Hop Count | Flow Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Next Header Next Header
8-bit selector. Identifies the type of header immediately 8-bit selector. Identifies the type of header immediately
following the DSR Flow State header. Uses the same values as following the DSR Flow State header. Uses the same values as
the IPv4 Protocol field [32]. the IPv4 Protocol field [34].
Flow State Header (F) Flow State Header (F)
Flag bit. MUST be set to 1. This bit is set in a DSR Flow Flag bit. MUST be set to 1. This bit is set in a DSR Flow
State header and clear in a DSR Options header (Section 6.1). State header and clear in a DSR Options header (Section 6.1).
Hop Count Hop Count
7-bit unsigned integer. The number of hops through which this 7-bit unsigned integer. The number of hops through which this
packet has been forwarded. packet has been forwarded.
Flow Identification Flow Identification
The flow ID for this flow, as described in Section 3.5.1. The flow ID for this flow, as described in Section 3.5.1.
7.2. Options and Extensions in DSR Options Header 7.2. New Options and Extensions in DSR Options Header
7.2.1. Timeout Option 7.2.1. Timeout Option
The Timeout option is defined for use in a DSR Options header to The Timeout option is defined for use in a DSR Options header to
indicate the amount of time before the expiration of the flow ID indicate the amount of time before the expiration of the flow ID
along which the packet is being sent. along which the packet is being sent.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 56, line 5 skipping to change at page 55, line 5
the DSR Options header. the DSR Options header.
New IP Destination Address New IP Destination Address
Indicates the next address to store in the Destination Address Indicates the next address to store in the Destination Address
field of the IP header. field of the IP header.
The Destination and Flow ID option MAY appear one or more times The Destination and Flow ID option MAY appear one or more times
within a DSR Options header. within a DSR Options header.
7.2.3. New Error Type Value for Unknown Flow 7.3. New Error Types for Route Error Option
7.3.1. Unknown Flow Type-Specific Information
A new Error Type value of 129 (Unknown Flow) is defined for use in A new Error Type value of 129 (Unknown Flow) is defined for use in
a Route Error option in a DSR Options header. The Type-Specific a Route Error option in a DSR Options header. The Type-Specific
Information for errors of this type is encoded as follows: Information for errors of this type is encoded as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Original IP Destination Address | | Original IP Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 57, line 5 skipping to change at page 56, line 5
Original IP Destination Address Original IP Destination Address
The IP Destination Address of the packet that caused the error. The IP Destination Address of the packet that caused the error.
Flow ID Flow ID
The Flow ID contained in the DSR Flow ID option that caused the The Flow ID contained in the DSR Flow ID option that caused the
error. error.
7.2.4. New Error Type Value for Default Flow Unknown 7.3.2. Default Flow Unknown Type-Specific Information
A new Error Type value of 130 (Default Flow Unknown) is defined A new Error Type value of 130 (Default Flow Unknown) is defined
for use in a Route Error option in a DSR Options header. The for use in a Route Error option in a DSR Options header. The
Type-Specific Information for errors of this type is encoded as Type-Specific Information for errors of this type is encoded as
follows: follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Original IP Destination Address | | Original IP Destination Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Original IP Destination Address Original IP Destination Address
The IP Destination Address of the packet that caused the error. The IP Destination Address of the packet that caused the error.
7.2.5. Acknowledgement Request Option Previous Hop Address Extension 7.4. New Acknowledgement Request Option Extension
7.4.1. Previous Hop Address Extension
When the Option Length field of an Acknowledgement Request option When the Option Length field of an Acknowledgement Request option
in a DSR Options header is greater than or equal to 6, a Previous in a DSR Options header is greater than or equal to 6, a Previous
Hop Address Extension is present. The option is then formatted as Hop Address Extension is present. The option is then formatted as
follows: follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option Type | Option Length | Packet Identifier | | Option Type | Option Length | Packet Identifier |
skipping to change at page 60, line 15 skipping to change at page 59, line 15
other headers that MUST be located in the packet before the DSR other headers that MUST be located in the packet before the DSR
Options header): Options header):
- Insert a DSR Options header after the IP header but before any - Insert a DSR Options header after the IP header but before any
other header that may be present. other header that may be present.
- Set the Next Header field of the DSR Options header to the - Set the Next Header field of the DSR Options header to the
Protocol number field of the packet's IP header. Protocol number field of the packet's IP header.
- Set the Protocol field of the packet's IP header to the Protocol - Set the Protocol field of the packet's IP header to the Protocol
number assigned for a DSR Options header (TBA???). number assigned for DSR (TBA???).
8.1.3. Adding a DSR Source Route Option to a Packet 8.1.3. Adding a DSR Source Route Option to a Packet
A node originating a packet adds a DSR Source Route option to the A node originating a packet adds a DSR Source Route option to the
packet, if necessary, in order to carry the source route from this packet, if necessary, in order to carry the source route from this
originating node to the final destination address of the packet. originating node to the final destination address of the packet.
Specifically, the node adding the DSR Source Route option constructs Specifically, the node adding the DSR Source Route option constructs
the DSR Source Route option and modifies the IP packet according to the DSR Source Route option and modifies the IP packet according to
the following sequence of steps: the following sequence of steps:
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set in the Route Reply, the node MUST flag the last hop from set in the Route Reply, the node MUST flag the last hop from
the Route Reply (the link from Address[n-1] to Address[n]) in the Route Reply (the link from Address[n-1] to Address[n]) in
its Route Cache as External. The value n here is the number of its Route Cache as External. The value n here is the number of
addresses in the source route being returned in the Route Reply addresses in the source route being returned in the Route Reply
option, or (Opt Data Len - 1) / 4. option, or (Opt Data Len - 1) / 4.
After possibly updating the node's Route Cache in response to After possibly updating the node's Route Cache in response to
the routing information in the Route Reply option, then if the the routing information in the Route Reply option, then if the
packet's IP Destination Address matches one of this node's IP packet's IP Destination Address matches one of this node's IP
addresses, the node MUST then process the Route Reply option as addresses, the node MUST then process the Route Reply option as
described in Section 8.2.5. described in Section 8.2.6.
- If the DSR Options header contains a Route Error option, - If the DSR Options header contains a Route Error option,
the node MUST process the Route Error option as described in the node MUST process the Route Error option as described in
Section 8.3.5. Section 8.3.5.
- If the DSR Options header contains an Acknowledgement Request - If the DSR Options header contains an Acknowledgement Request
option, the node MUST process the Acknowledgement Request option option, the node MUST process the Acknowledgement Request option
as described in Section 8.3.3. as described in Section 8.3.3.
- If the DSR Options header contains an Acknowledgement option, - If the DSR Options header contains an Acknowledgement option,
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- Discard the overheard packet, since the packet has been received - Discard the overheard packet, since the packet has been received
before its normal traversal of the packet's source route would before its normal traversal of the packet's source route would
have caused it to reach this receiving node. Another copy of have caused it to reach this receiving node. Another copy of
the packet will normally arrive at this node as indicated in the packet will normally arrive at this node as indicated in
the packet's source route; discarding this initial copy of the the packet's source route; discarding this initial copy of the
packet, which triggered the gratuitous Route Reply, will prevent packet, which triggered the gratuitous Route Reply, will prevent
the duplication of this packet that would otherwise occur. the duplication of this packet that would otherwise occur.
If the packet is not discarded as part of automatic route shortening If the packet is not discarded as part of automatic route shortening
above, then the node MUST process the option according to the above, then the node MUST process the Source Route option according
following sequence of steps: to the following sequence of steps:
- If the value of the Segments Left field in the DSR Source Route - If the value of the Segments Left field in the DSR Source Route
option equals 0, then remove the DSR Source Route option from the option equals 0, then remove the DSR Source Route option from the
DSR Options header. DSR Options header.
- Else, let n equal (Opt Data Len - 2) / 4. This is the number of - Else, let n equal (Opt Data Len - 2) / 4. This is the number of
addresses in the DSR Source Route option. addresses in the DSR Source Route option.
- If the value of the Segments Left field is greater than n, then - If the value of the Segments Left field is greater than n, then
send an ICMP Parameter Problem, Code 0, message [29] to the IP send an ICMP Parameter Problem, Code 0, message [31] to the IP
Source Address, pointing to the Segments Left field, and discard Source Address, pointing to the Segments Left field, and discard
the packet. Do not process the DSR Source Route option further. the packet. Do not process the DSR Source Route option further.
- Else, decrement the value of the Segments Left field by 1. Let i - Else, decrement the value of the Segments Left field by 1. Let i
equal n minus Segments Left. This is the index of the next equal n minus Segments Left. This is the index of the next
address to be visited in the Address vector. address to be visited in the Address vector.
- If Address[i] or the IP Destination Address is a multicast - If Address[i] or the IP Destination Address is a multicast
address, then discard the packet. Do not process the DSR Source address, then discard the packet. Do not process the DSR Source
Route option further. Route option further.
- If this node has more than one network interface and if
Address[i] is the address of one this node's network interfaces,
then this indicates a change in the network interface to use in
forwarding the packet, as described in Section 8.4. In this
case, decrement the value of the Segments Left field by 1 to
skip over this address (that indicated the change of network
interface) and go to the first step above (checking the value of
the Segments Left field) to continue processing this Source Route
option; in further processing of this Source Route option, the
indicated new network interface MUST be used in forwarding the
packet.
- If the MTU of the link over which this node would transmit - If the MTU of the link over which this node would transmit
the packet to forward it to the node Address[i] is less than the packet to forward it to the node Address[i] is less than
the size of the packet, the node MUST either discard the the size of the packet, the node MUST either discard the
packet and send an ICMP Packet Too Big message to the packet's packet and send an ICMP Packet Too Big message to the packet's
Source Address [29] or fragment it as specified in Section 8.5. Source Address [31] or fragment it as specified in Section 8.5.
- Forward the packet to the IP address specified in the Address[i] - Forward the packet to the IP address specified in the Address[i]
field of the IP header, following normal IP forwarding field of the IP header, following normal IP forwarding
procedures, including checking and decrementing the Time-to-Live procedures, including checking and decrementing the Time-to-Live
(TTL) field in the packet's IP header [30, 3]. In this (TTL) field in the packet's IP header [32, 3]. In this
forwarding of the packet, the next-hop node (identified by forwarding of the packet, the next-hop node (identified by
Address[i]) MUST be treated as a direct neighbor node: the Address[i]) MUST be treated as a direct neighbor node: the
transmission to that next node MUST be done in a single IP transmission to that next node MUST be done in a single IP
forwarding hop, without Route Discovery and without searching the forwarding hop, without Route Discovery and without searching the
Route Cache. Route Cache.
- In forwarding the packet, perform Route Maintenance for the - In forwarding the packet, perform Route Maintenance for the
next hop of the packet, by verifying that the next-hop node is next hop of the packet, by verifying that the next-hop node is
reachable, as described in Section 8.3. reachable, as described in Section 8.3.
skipping to change at page 68, line 38 skipping to change at page 67, line 38
update that information in the table entry for use in the next Route update that information in the table entry for use in the next Route
Request initiated for this target. In particular: Request initiated for this target. In particular:
- The Route Request Table entry for a target node records the - The Route Request Table entry for a target node records the
Time-to-Live (TTL) field used in the IP header of the Route Time-to-Live (TTL) field used in the IP header of the Route
Request for the last Route Discovery initiated by this node for Request for the last Route Discovery initiated by this node for
that target node. This value allows the node to implement a that target node. This value allows the node to implement a
variety of algorithms for controlling the spread of its Route variety of algorithms for controlling the spread of its Route
Request on each Route Discovery initiated for a target. As Request on each Route Discovery initiated for a target. As
examples, two possible algorithms for this use of the TTL field examples, two possible algorithms for this use of the TTL field
are described in Section 3.3.4. are described in Section 3.3.3.
- The Route Request Table entry for a target node records the - The Route Request Table entry for a target node records the
number of consecutive Route Requests initiated for this target number of consecutive Route Requests initiated for this target
since receiving a valid Route Reply giving a route to that target since receiving a valid Route Reply giving a route to that target
node, and the remaining amount of time before which this node MAY node, and the remaining amount of time before which this node MAY
next attempt at a Route Discovery for that target node. next attempt at a Route Discovery for that target node.
A node MUST use these values to implement a back-off algorithm to A node MUST use these values to implement a back-off algorithm to
limit the rate at which this node initiates new Route Discoveries limit the rate at which this node initiates new Route Discoveries
for the same target address. In particular, until a valid Route for the same target address. In particular, until a valid Route
skipping to change at page 70, line 4 skipping to change at page 69, line 4
as part of the Route Discovery. as part of the Route Discovery.
- Else, the node MUST examine the route recorded in the Route - Else, the node MUST examine the route recorded in the Route
Request option (the IP Source Address field and the sequence of Request option (the IP Source Address field and the sequence of
Address[i] fields) to determine if this node's own IP address Address[i] fields) to determine if this node's own IP address
already appears in this list of addresses. If so, the node MUST already appears in this list of addresses. If so, the node MUST
discard the entire packet carrying the Route Request option. discard the entire packet carrying the Route Request option.
- Else, if the Route Request was received through a network - Else, if the Route Request was received through a network
interface that requires physically bidirectional links for interface that requires physically bidirectional links for
unicast transmission, the node MUST check if the Request was last unicast transmission, the node MUST check if the Route Request
forwarded by a node on its blacklist. If such an entry is found, was last forwarded by a node on its Blacklist (Section 4.6).
and the state of the unidirectional link is "probable", then the If such an entry is found in the Blacklist, and the state of
Request MUST be silently discarded. the unidirectional link is "probable", then the Request MUST be
silently discarded.
- Else, if the Route Request was received through a network - Else, if the Route Request was received through a network
interface that requires physically bidirectional links for interface that requires physically bidirectional links for
unicast transmission, the node MUST check if the Request was last unicast transmission, the node MUST check if the Route Request
forwarded by a node on its blacklist. If such an entry is found, was last forwarded by a node on its Blacklist. If such an entry
and the state of the unidirectional link is "questionable", is found in the Blacklist, and the state of the unidirectional
then the node MUST create and unicast a Route Request packet to link is "questionable", then the node MUST create and unicast
that previous node, setting the IP Time-To-Live (TTL) to 1 to a Route Request packet to that previous node, setting the
prevent the Request from being propagated. If the node receives IP Time-To-Live (TTL) to 1 to prevent the Request from being
a Route Reply in response to the new Request, it MUST remove the propagated. If the node receives a Route Reply in response to
blacklist entry for that node, and SHOULD continue processing. the new Request, it MUST remove the Blacklist entry for that
If the node does not receive a Route Reply within some reasonable node, and SHOULD continue processing. If the node does not
amount of time, MUST silently discard the Route Request packet. receive a Route Reply within some reasonable amount of time, the
node MUST silently discard the Route Request packet.
- Else, the node MUST search its Route Request Table for an entry - Else, the node MUST search its Route Request Table for an entry
for the initiator of this Route Request (the IP Source Address for the initiator of this Route Request (the IP Source Address
field). If such an entry is found in the table, the node MUST field). If such an entry is found in the table, the node MUST
search the cache of Identification values of recently received search the cache of Identification values of recently received
Route Requests in that table entry, to determine if an entry Route Requests in that table entry, to determine if an entry
is present in the cache matching the Identification value is present in the cache matching the Identification value
and target node address in this Route Request. If such an and target node address in this Route Request. If such an
(Identification, target address) entry is found in this cache in (Identification, target address) entry is found in this cache in
this entry in the Route Request Table, then the node MUST discard this entry in the Route Request Table, then the node MUST discard
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o Add an entry for this Route Request in its cache of o Add an entry for this Route Request in its cache of
(Identification, target address) values of recently received (Identification, target address) values of recently received
Route Requests. Route Requests.
o Conceptually create a copy of this entire packet and perform o Conceptually create a copy of this entire packet and perform
the following steps on the copy of the packet. the following steps on the copy of the packet.
o Append this node's own IP address to the list of Address[i] o Append this node's own IP address to the list of Address[i]
values in the Route Request, and increase the value of the values in the Route Request, and increase the value of the
Opt Data Len field in the Route Request by 4 (the size of an Opt Data Len field in the Route Request by 4 (the size of
IP address). an IP address). However, if the node has multiple network
interfaces, this step MUST be modified by the special
processing specified in Section sec:multiple.
o This node SHOULD search its own Route Cache for a route o This node SHOULD search its own Route Cache for a route
(from itself, as if it were the source of a packet) to the (from itself, as if it were the source of a packet) to the
target of this Route Request. If such a route is found in target of this Route Request. If such a route is found in
its Route Cache, then this node SHOULD follow the procedure its Route Cache, then this node SHOULD follow the procedure
outlined in Section 8.2.3 to return a "cached Route Reply" outlined in Section 8.2.3 to return a "cached Route Reply"
to the initiator of this Route Request, if permitted by the to the initiator of this Route Request, if permitted by the
restrictions specified there. restrictions specified there.
o If the node does not return a cached Route Reply, then this o If the node does not return a cached Route Reply, then this
node SHOULD link-layer re-broadcast this copy of the packet, node SHOULD transmit this copy of the packet as a link-layer
with a short jitter delay before the broadcast is sent. The broadcast, with a short jitter delay before the broadcast is
jitter period SHOULD be chosen as a random period, uniformly sent. The jitter period SHOULD be chosen as a random period,
distributed between 0 and BroadcastJitter. uniformly distributed between 0 and BroadcastJitter.
8.2.3. Generating a Route Reply using the Route Cache 8.2.3. Generating a Route Reply using the Route Cache
As described in Section 3.3.2, it is possible for a node processing a As described in Section 3.3.2, it is possible for a node processing a
received Route Request to avoid propagating the Route Request further received Route Request to avoid propagating the Route Request further
toward the target of the Request, if this node has in its Route Cache toward the target of the Request, if this node has in its Route Cache
a route from itself to this target. Such a Route Reply generated by a route from itself to this target. Such a Route Reply generated by
a node from its own cached route to the target of a Route Request is a node from its own cached route to the target of a Route Request is
called a "cached Route Reply", and this mechanism can greatly reduce called a "cached Route Reply", and this mechanism can greatly reduce
the overall overhead of Route Discovery on the network by reducing the overall overhead of Route Discovery on the network by reducing
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to this target node, obtained from the node's Route Cache. In to this target node, obtained from the node's Route Cache. In
appending this cached route to the source route for the reply, appending this cached route to the source route for the reply,
the address of this node itself MUST be excluded, since it is the address of this node itself MUST be excluded, since it is
already listed as Address[n]. already listed as Address[n].
- Send a Route Reply to the initiator of the Route Request, using - Send a Route Reply to the initiator of the Route Request, using
the procedure defined in Section 8.2.4. The initiator of the the procedure defined in Section 8.2.4. The initiator of the
Route Request is indicated in the Source Address field in the Route Request is indicated in the Source Address field in the
packet's IP header. packet's IP header.
Before sending the cached Route Reply, however, the node MAY delay
the Reply in order to help prevent a possible Route Reply "storm", as
described in Section 8.2.5.
If the node returns a cached Route Reply as described above, If the node returns a cached Route Reply as described above,
then the node MUST NOT propagate the Route Request further (i.e., then the node MUST NOT propagate the Route Request further (i.e.,
the node MUST NOT rebroadcast the Route Request). In this case, the node MUST NOT rebroadcast the Route Request). In this case,
instead, if the packet contains no other DSR options and contains instead, if the packet contains no other DSR options and contains
no payload after the DSR Options header (e.g., the Route Request is no payload after the DSR Options header (e.g., the Route Request is
not piggybacked on a TCP or UDP packet), then the node SHOULD simply not piggybacked on a TCP or UDP packet), then the node SHOULD simply
discard the packet. Otherwise (if the packet contains other DSR discard the packet. Otherwise (if the packet contains other DSR
options or contains any payload after the DSR Options header), the options or contains any payload after the DSR Options header), the
node SHOULD forward the packet along the cached route to the target node SHOULD forward the packet along the cached route to the target
of the Route Request. Specifically, if the node does so, it MUST use of the Route Request. Specifically, if the node does so, it MUST use
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piggybacking prevents a loop wherein the target of the new Route piggybacking prevents a loop wherein the target of the new Route
Request (which was itself the initiator of the original Route Request (which was itself the initiator of the original Route
Request) must do another Route Request in order to return its Request) must do another Route Request in order to return its
Route Reply. Route Reply.
If sending the Route Reply to the initiator of the Route Request If sending the Route Reply to the initiator of the Route Request
does not require performing a Route Discovery, a node SHOULD send a does not require performing a Route Discovery, a node SHOULD send a
unicast Route Reply in response to every Route Request it receives unicast Route Reply in response to every Route Request it receives
for which it is the target node. for which it is the target node.
8.2.5. Processing a Received Route Reply Option 8.2.5. Preventing Route Reply Storms
The ability for nodes to reply to a Route Request based on
information in their Route Caches, as described in Sections 3.3.2
and 8.2.3, could result in a possible Route Reply "storm" in some
cases. In particular, if a node broadcasts a Route Request for a
target node for which the node's neighbors have a route in their
Route Caches, each neighbor may attempt to send a Route Reply,
thereby wasting bandwidth and possibly increasing the number of
network collisions in the area.
For example, the figure below shows a situation in which nodes B, C,
D, E, and F all receive A's Route Request for target G, and each has
the indicated route cached for this target:
+-----+ +-----+
| D |< >| C |
+-----+ \ / +-----+
Cache: C - B - G \ / Cache: B - G
\ +-----+ /
-| A |-
+-----+\ +-----+ +-----+
| | \--->| B | | G |
/ \ +-----+ +-----+
/ \ Cache: G
v v
+-----+ +-----+
| E | | F |
+-----+ +-----+
Cache: F - B - G Cache: B - G
Normally, each of these nodes would attempt to reply from its own
Route Cache, and they would thus all send their Route Replies at
about the same time, since they all received the broadcast Route
Request at about the same time. Such simultaneous Route Replies
from different nodes all receiving the Route Request may cause local
congestion in the wireless network and may create packet collisions
among some or all of these Replies if the MAC protocol in use does
not provide sufficient collision avoidance for these packets. In
addition, it will often be the case that the different replies will
indicate routes of different lengths, as shown in this example.
In order to reduce these effects, if a node can put its network
interface into promiscuous receive mode, it MAY delay sending its
own Route Reply for a short period, while listening to see if the
initiating node begins using a shorter route first. Specifically,
this node MAY delay sending its own Route Reply for a random period
d = H * (h - 1 + r)
where h is the length in number of network hops for the route to be
returned in this node's Route Reply, r is a random floating point
number between 0 and 1, and H is a small constant delay (at least
twice the maximum wireless link propagation delay) to be introduced
per hop. This delay effectively randomizes the time at which each
node sends its Route Reply, with all nodes sending Route Replies
giving routes of length less than h sending their Replies before this
node, and all nodes sending Route Replies giving routes of length
greater than h sending their Replies after this node.
Within the delay period, this node promiscuously receives all
packets, looking for data packets from the initiator of this Route
Discovery destined for the target of the Discovery. If such a data
packet received by this node during the delay period uses a source
route of length less than or equal to h, this node may infer that the
initiator of the Route Discovery has already received a Route Reply
giving an equally good or better route. In this case, this node
SHOULD cancel its delay timer and SHOULD NOT send its Route Reply for
this Route Discovery.
8.2.6. Processing a Received Route Reply Option
Section 8.1.4 describes the general processing for a received packet, Section 8.1.4 describes the general processing for a received packet,
including the addition of routing information from options in the including the addition of routing information from options in the
packet's DSR Options header to the receiving node's Route Cache. packet's DSR Options header to the receiving node's Route Cache.
If the received packet contains a Route Reply, no additional special If the received packet contains a Route Reply, no additional special
processing of the Route Reply option is required beyond what is processing of the Route Reply option is required beyond what is
described there. As described in Section 4.1 anytime a node adds described there. As described in Section 4.1 anytime a node adds
new information to its Route Cache (including the information added new information to its Route Cache (including the information added
from this Route Reply option), the node SHOULD check each packet in from this Route Reply option), the node SHOULD check each packet in
its own Send Buffer (Section 4.2) to determine whether a route to its own Send Buffer (Section 4.2) to determine whether a route to
that packet's IP Destination Address now exists in the node's Route that packet's IP Destination Address now exists in the node's Route
Cache (including the information just added to the Cache). If so, Cache (including the information just added to the Cache). If so,
the packet SHOULD then be sent using that route and removed from the the packet SHOULD then be sent using that route and removed from the
Send Buffer. This general procedure handles all processing required Send Buffer. This general procedure handles all processing required
for a received Route Reply option. for a received Route Reply option.
When a MAC protocol requires bidirectional links for unicast When using a MAC protocol that requires bidirectional links for
transmission, a unidirectional link may be discovered by the unicast transmission, a unidirectional link may be discovered by the
propagation of the Route Request. When the Route Reply is sent over propagation of the Route Request. When the Route Reply is sent over
the reverse path, a forwarding node may discover that the next-hop is the reverse path, a forwarding node may discover that the next-hop is
unreachable. In this case, it MUST add the next-hop address to its unreachable. In this case, it MUST add the next-hop address to its
blacklist. Blacklist (Section 4.6).
8.3. Route Maintenance Processing 8.3. Route Maintenance Processing
Route Maintenance is the mechanism by which a source node S is able Route Maintenance is the mechanism by which a source node S is able
to detect, while using a source route to some destination node D, to detect, while using a source route to some destination node D,
if the network topology has changed such that it can no longer use if the network topology has changed such that it can no longer use
its route to D because a link along the route no longer works. When its route to D because a link along the route no longer works. When
Route Maintenance indicates that a source route is broken, S can Route Maintenance indicates that a source route is broken, S can
attempt to use any other route it happens to know to D, or can invoke attempt to use any other route it happens to know to D, or can invoke
Route Discovery again to find a new route for subsequent packets Route Discovery again to find a new route for subsequent packets
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acknowledgements. acknowledgements.
In using passive acknowledgements for a packet that it originates or In using passive acknowledgements for a packet that it originates or
forwards, a node considers the later receipt of a new packet (e.g., forwards, a node considers the later receipt of a new packet (e.g.,
with promiscuous receive mode enabled on its network interface) to be with promiscuous receive mode enabled on its network interface) to be
an acknowledgement of this first packet if both of the following two an acknowledgement of this first packet if both of the following two
tests succeed: tests succeed:
- The Source Address, Destination Address, Protocol, - The Source Address, Destination Address, Protocol,
Identification, and Fragment Offset fields in the IP header Identification, and Fragment Offset fields in the IP header
of the two packets MUST match [30], and of the two packets MUST match [32], and
- If either packet contains a DSR Source Route header, both packets - If either packet contains a DSR Source Route header, both packets
MUST contain one, and the value in the Segments Left field in the MUST contain one, and the value in the Segments Left field in the
DSR Source Route header of the new packet MUST be less than that DSR Source Route header of the new packet MUST be less than that
in the first packet. in the first packet.
When a node hears such a passive acknowledgement for any packet in When a node hears such a passive acknowledgement for any packet in
its Maintenance Buffer, that node SHOULD remove that packet, as well its Maintenance Buffer, that node SHOULD remove that packet, as well
as any other packets in its Maintenance Buffer with the same next-hop as any other packets in its Maintenance Buffer with the same next-hop
destination, from its Maintenance Buffer. destination, from its Maintenance Buffer.
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- If the packet contains an Acknowledgement option, then this node - If the packet contains an Acknowledgement option, then this node
MUST NOT process the Acknowledgement Request option. MUST NOT process the Acknowledgement Request option.
If neither of the tests above fails, then this node MUST process the If neither of the tests above fails, then this node MUST process the
Acknowledgement Request option by sending an Acknowledgement option Acknowledgement Request option by sending an Acknowledgement option
to the previous-hop node; to do so, the node performs the following to the previous-hop node; to do so, the node performs the following
sequence of steps: sequence of steps:
- Create a packet and set the IP Protocol field to the protocol - Create a packet and set the IP Protocol field to the protocol
number assigned for a DSR Options header (TBA???). number assigned for DSR (TBA???).
- Set the IP Source Address field in this packet to the IP address - Set the IP Source Address field in this packet to the IP address
of this node, copied from the source route in the DSR Source of this node, copied from the source route in the DSR Source
Route option in that packet (or from the IP Destination Address Route option in that packet (or from the IP Destination Address
field of the packet, if the packet does not contain a DSR Source field of the packet, if the packet does not contain a DSR Source
Route option). Route option).
- Set the IP Destination Address field in this packet to the IP - Set the IP Destination Address field in this packet to the IP
address of the previous-hop node, copied from the source route address of the previous-hop node, copied from the source route
in the DSR Source Route option in that packet (or from the IP in the DSR Source Route option in that packet (or from the IP
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When a node receives a packet with both an Acknowledgement option When a node receives a packet with both an Acknowledgement option
and an Acknowledgement Request option, if that node is not the and an Acknowledgement Request option, if that node is not the
destination of the Acknowledgement option (the IP Destination Address destination of the Acknowledgement option (the IP Destination Address
of the packet), then the Acknowledgement Request option MUST of the packet), then the Acknowledgement Request option MUST
be ignored. Otherwise (that node is the destination of the be ignored. Otherwise (that node is the destination of the
Acknowledgement option), that node MUST process the Acknowledgement Acknowledgement option), that node MUST process the Acknowledgement
Request option by returning an Acknowledgement option according to Request option by returning an Acknowledgement option according to
the following sequence of steps: the following sequence of steps:
- Create a packet and set the IP Protocol field to the protocol - Create a packet and set the IP Protocol field to the protocol
number assigned for a DSR Options header (TBA???). number assigned for DSR (TBA???).
- Set the IP Source Address field in this packet to the IP address - Set the IP Source Address field in this packet to the IP address
of this node, copied from the source route in the DSR Source of this node, copied from the source route in the DSR Source
Route option in that packet (or from the IP Destination Address Route option in that packet (or from the IP Destination Address
field of the packet, if the packet does not contain a DSR Source field of the packet, if the packet does not contain a DSR Source
Route option). Route option).
- Set the IP Destination Address field in this packet to the IP - Set the IP Destination Address field in this packet to the IP
address of the node originating the Acknowledgement option. address of the node originating the Acknowledgement option.
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- Transmit the packet to the next-hop node on the new source route - Transmit the packet to the next-hop node on the new source route
in the packet, using the forwarding procedure described in in the packet, using the forwarding procedure described in
Section 8.1.5. Section 8.1.5.
As described in Section 8.3.4, the node in this case also SHOULD As described in Section 8.3.4, the node in this case also SHOULD
return a Route Error to the original sender of the packet. If the return a Route Error to the original sender of the packet. If the
node chooses to salvage the packet, it SHOULD do so after originating node chooses to salvage the packet, it SHOULD do so after originating
the Route Error. the Route Error.
8.4. Multiple Interface Support 8.4. Multiple Network Interface Support
A node in DSR MAY have multiple network interfaces that support A node using DSR MAY have multiple network interfaces that support
ad hoc network routing. This section describes special packet ad hoc network routing. This section describes special packet
processing at such nodes. processing at such nodes.
A node with multiple network interfaces MUST have some policy for A node with multiple network interfaces MUST have some policy for
determining which Request packets are forwarded out which network determining which Route Request packets are forwarded out which
interfaces. For example, a node MAY choose to forward all Requests network interfaces. For example, a node MAY choose to forward all
out all network interfaces. Route Requests out all network interfaces.
When a node with multiple network interfaces propagates a Route When a node with multiple network interfaces propagates a Route
Request on an network interface other than the one it received the Request on an network interface other than the one one which it
Request on, it MUST modify the address list between receipt and received the Route Request, it MUST modify the address list between
re-propagation as follows: receipt and propagation as follows:
- Append the address of the incoming interface
- If the incoming interface and outgoing interface differ in
whether or not they require bidirectionality for unicast
transmission, append the address 127.0.0.1
- If the incoming interface and outgoing interface differ in - Append the address of the incoming network interface.
whether or not unidirectional links are common, append the
address 127.0.0.2
- Append the address of the outgoing interface - Append the address of the outgoing network interface.
When a node forwards a packet containing a source route, it MUST When a node forwards a packet containing a source route, it MUST
assume that the next hop is reachable on the incoming interface, assume that the next-hop node is reachable on the incoming network
unless the next hop is the address of one of this node's interfaces, interface, unless the next hop is the address of one of this node's
in which case this node MUST process the packet in the same way as if network interfaces, in which case this node MUST skip over this
the node had just received it from that interface. address in the source route and process the packet in the same way as
if it had just received it from that network interface, as described
in section 8.1.5.
If a node which previously had multiple network interfaces receives a If a node that previously had multiple network interfaces receives
packet sent with a source route specifying an interface change to an a packet sent with a source route specifying a change to a network
interface that is no longer available, it MAY send a Route Error to interface that is no longer available, it MAY send a Route Error to
the source of the packet without attempting to forward the packet on the source of the packet without attempting to forward the packet
the incoming interface, unless the network uses an autoconfiguration on the incoming network interface, unless the network uses an
mechanism that may have allowed another node to acquire the now autoconfiguration mechanism that may have allowed another node to
unused address of the unavailable interface. acquire the now unused address of the unavailable network interface.
Source routes MUST never contain the special addresses 127.0.0.1 and
127.0.0.2.
8.5. Fragmentation and Reassembly 8.5. IP Fragmentation and Reassembly
When a node using DSR wishes to fragment a packet that contains a DSR When a node using DSR wishes to fragment a packet that contains a DSR
header not containing a Route Request option, it MUST perform the header not containing a Route Request option, it MUST perform the
following sequence of steps: following sequence of steps:
- Remove the DSR Options header from the packet. - Remove the DSR Options header from the packet.
- Fragment the packet. - Fragment the packet. When determining the size of each fragment
to create from the original packet, the fragment size MUST be
reduced by the size of the DSR Options header from the original
packet.
- IP-in-IP encapsulate each fragment. - IP-in-IP encapsulate each fragment [28]. The IP Destination
address of the outer (encapsulating) packet MUST be set equal to
the IP Destination address of the original packet.
- Add the DSR Options header to each fragment. If a Source Route - Add the DSR Options header from the original packet to each
header is present in the DSR Options header, increment the resulting encapsulating packet. If a Source Route header is
Salvage field. present in the DSR Options header, increment the Salvage field.
When a node using the DSR protocol receives an IP-in-IP encapsulated When a node using the DSR protocol receives an IP-in-IP encapsulated
packet destined to itself, it SHOULD decapsulate the packet and packet destined to itself, it SHOULD decapsulate the packet [28] and
reassemble any fragments contained inside, in accordance with then process the inner packet according to standard IP reassembly
RFC 791 [30]. processing [32].
8.6. Flow State Processing 8.6. Flow State Processing
A node implementing the optional DSR flow state extension MUST follow A node implementing the optional DSR flow state extension MUST follow
these additional processing steps. these additional processing steps.
8.6.1. Originating a Packet 8.6.1. Originating a Packet
When originating any packet to be routed using flow state, a node When originating any packet to be routed using flow state, a node
using DSR flow state MUST: using DSR flow state MUST:
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- Insert a DSR Flow State header after the IP header and any - Insert a DSR Flow State header after the IP header and any
Hop-by-Hop Options header that may already be in the packet, but Hop-by-Hop Options header that may already be in the packet, but
before any other header that may be present. before any other header that may be present.
- Set the Next Header field of the DSR Flow State header to the - Set the Next Header field of the DSR Flow State header to the
Next Header field of the previous header (either an IP header or Next Header field of the previous header (either an IP header or
a Hop-by-Hop Options header). a Hop-by-Hop Options header).
- Set the Next Header field of the previous header to the Protocol - Set the Next Header field of the previous header to the Protocol
number assigned to DSR Options headers. number assigned for DSR (TBA???).
8.6.3. Receiving a Packet 8.6.3. Receiving a Packet
This section describes processing only for packets that are sent to This section describes processing only for packets that are sent to
the processing node as the next-hop node; that is, when the MAC-layer the processing node as the next-hop node; that is, when the MAC-layer
destination address is the MAC address of this node. Otherwise, the destination address is the MAC address of this node. Otherwise, the
process described in Sections 8.6.5 should be followed. process described in Sections 8.6.5 should be followed.
The flow along which a packet is being sent is considered to be in The flow along which a packet is being sent is considered to be in
the Flow Table if the triple (IP Source Address, IP Destination the Flow Table if the triple (IP Source Address, IP Destination
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o On receiving a Route Request that this node has not o On receiving a Route Request that this node has not
previously seen for which this node is not the destination, previously seen for which this node is not the destination,
discard the packet and stop processing. discard the packet and stop processing.
o On receiving any Route Request, add appropriate links to the o On receiving any Route Request, add appropriate links to the
cache, as specified in Section 8.2.2. cache, as specified in Section 8.2.2.
o On receiving a Route Reply that this node is the Requester o On receiving a Route Reply that this node is the Requester
for, remove the Route Reply from the packet and process it as for, remove the Route Reply from the packet and process it as
specified in Section 8.2.5. specified in Section 8.2.6.
o On receiving any Route Reply, add appropriate links to the o On receiving any Route Reply, add appropriate links to the
cache, as specified in Section 8.2.5. cache, as specified in Section 8.2.6.
o On receiving any Route Error of type NODE_UNREACHABLE, o On receiving any Route Error of type NODE_UNREACHABLE,
remove appropriate links to the cache, as specified in remove appropriate links to the cache, as specified in
Section 8.3.5. Section 8.3.5.
o On receiving a Route Error of type NODE_UNREACHABLE that o On receiving a Route Error of type NODE_UNREACHABLE that
this node is the Error Destination Address of, remove the this node is the Error Destination Address of, remove the
Route Error from the packet and process it as specified Route Error from the packet and process it as specified
in Section 8.3.5. It also MUST stop originating packets in Section 8.3.5. It also MUST stop originating packets
along any flows using the link from Error Source Address to along any flows using the link from Error Source Address to
skipping to change at page 96, line 21 skipping to change at page 97, line 21
is not required to use these names for the configuration variables, is not required to use these names for the configuration variables,
so long as the external behavior of the implementation is consistent so long as the external behavior of the implementation is consistent
with that described in this document. with that described in this document.
For each configuration variable below, the default value is specified For each configuration variable below, the default value is specified
to simplify configuration. In particular, the default values given to simplify configuration. In particular, the default values given
below are chosen for a DSR network running over 2 Mbps IEEE 802.11 below are chosen for a DSR network running over 2 Mbps IEEE 802.11
network interfaces using the Distributed Coordination Function (DCF) network interfaces using the Distributed Coordination Function (DCF)
MAC with RTS and CTS [13, 5]. MAC with RTS and CTS [13, 5].
DiscoveryHopLimit 255 hops
BroadcastJitter 10 milliseconds BroadcastJitter 10 milliseconds
RouteCacheTimeout 300 seconds RouteCacheTimeout 300 seconds
SendBufferTimeout 30 seconds SendBufferTimeout 30 seconds
RequestTableSize 64 nodes RequestTableSize 64 nodes
RequestTableIds 16 identifiers RequestTableIds 16 identifiers
MaxRequestRexmt 16 retransmissions MaxRequestRexmt 16 retransmissions
MaxRequestPeriod 10 seconds MaxRequestPeriod 10 seconds
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GratReplyHoldoff 1 second GratReplyHoldoff 1 second
In addition, the following protocol constant MUST be supported by any In addition, the following protocol constant MUST be supported by any
implementation of the DSR protocol: implementation of the DSR protocol:
MAX_SALVAGE_COUNT 15 salvages MAX_SALVAGE_COUNT 15 salvages
10. IANA Considerations 10. IANA Considerations
This document specifies the DSR Options header, which requires an IP This document specifies the DSR Options header and DSR Flow State
Protocol number. header, which require an IP Protocol number. A single IP protocol
number can be used for both header types, since they can be
This document also specifies the DSR Flow State header, which distinguished by the Flow State Header (F) bit in each header.
requires an IP Protocol number.
In addition, this document proposes use of the value "No Next Header" In addition, this document proposes use of the value "No Next Header"
(originally defined for use in IPv6) within an IPv4 packet, to (originally defined for use in IPv6) within an IPv4 packet, to
indicate that no further header follows a DSR Options header. indicate that no further header follows a DSR Options header.
Finally, this document introduces a number of DSR options for use in Finally, this document introduces a number of DSR options for use in
the DSR Options header, and additional new DSR options may be defined the DSR Options header, and additional new DSR options may be defined
in the future. Each of these options requires a unique Option Type in the future. Each of these options requires a unique Option Type
value, with the most significant 3 bits (that is, Option Type & 0xE0) value, with the most significant 3 bits (that is, Option Type & 0xE0)
encoded as defined in Section 6.1. It is necessary only that each encoded as defined in Section 6.1. It is necessary only that each
Option Type value be unique, not that they be unique in the remaining Option Type value be unique, not that they be unique in the remaining
5 bits of the value after these 3 most significant bits. 5 bits of the value after these 3 most significant bits. Assignment
of new values for DSR options will be by Expert Review [25], with the
authors of this document serving as the Designated Experts.
11. Security Considerations 11. Security Considerations
This document does not specifically address security concerns. This This document does not specifically address security concerns. This
document does assume that all nodes participating in the DSR protocol document does assume that all nodes participating in the DSR protocol
do so in good faith and without malicious intent to corrupt the do so in good faith and without malicious intent to corrupt the
routing ability of the network. routing ability of the network.
Depending on the threat model, a number of different mechanisms can Depending on the threat model, a number of different mechanisms can
be used to secure DSR. For example, in an environment where node be used to secure DSR. For example, in an environment where node
compromise is unrealistic and where where all the nodes participating compromise is unrealistic and where where all the nodes participating
in the DSR protocol share a common goal that motivates their in the DSR protocol share a common goal that motivates their
participation in the protocol, the communications between the nodes participation in the protocol, the communications between the nodes
can be encrypted at the physical channel or link layer to prevent can be encrypted at the physical channel or link layer to prevent
attack by outsiders. Cryptographic approaches, such as that provided attack by outsiders. Cryptographic approaches, such as that provided
by Ariadne [12] or SRP [26], can resist stronger attacks. by Ariadne [12] or SRP [27], can resist stronger attacks.
Appendix A. Link-MaxLife Cache Description Appendix A. Link-MaxLife Cache Description
As guidance to implementors of DSR, the description below outlines As guidance to implementors of DSR, the description below outlines
the operation of a possible implementation of a Route Cache for DSR the operation of a possible implementation of a Route Cache for DSR
that has been shown to outperform other other caches studied in that has been shown to outperform other other caches studied in
detailed simulations. Use of this design for the Route Cache is detailed simulations. Use of this design for the Route Cache is
recommended in implementations of DSR. recommended in implementations of DSR.
This cache, called "Link-MaxLife" [10], is a link cache, in that each This cache, called "Link-MaxLife" [10], is a link cache, in that each
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When designing DSR, we had to determine at what layer within When designing DSR, we had to determine at what layer within
the protocol hierarchy to implement ad hoc network routing. We the protocol hierarchy to implement ad hoc network routing. We
considered two different options: routing at the link layer (ISO considered two different options: routing at the link layer (ISO
layer 2) and routing at the network layer (ISO layer 3). Originally, layer 2) and routing at the network layer (ISO layer 3). Originally,
we opted to route at the link layer for several reasons: we opted to route at the link layer for several reasons:
- Pragmatically, running the DSR protocol at the link layer - Pragmatically, running the DSR protocol at the link layer
maximizes the number of mobile nodes that can participate in maximizes the number of mobile nodes that can participate in
ad hoc networks. For example, the protocol can route equally ad hoc networks. For example, the protocol can route equally
well between IPv4 [30], IPv6 [7], and IPX [35] nodes. well between IPv4 [32], IPv6 [7], and IPX [37] nodes.
- Historically [15, 16], DSR grew from our contemplation of - Historically [15, 16], DSR grew from our contemplation of
a multi-hop propagating version of the Internet's Address a multi-hop propagating version of the Internet's Address
Resolution Protocol (ARP) [28], as well as from the routing Resolution Protocol (ARP) [30], as well as from the routing
mechanism used in IEEE 802 source routing bridges [27]. These mechanism used in IEEE 802 source routing bridges [29]. These
are layer 2 protocols. are layer 2 protocols.
- Technically, we designed DSR to be simple enough that it could - Technically, we designed DSR to be simple enough that it could
be implemented directly in the firmware inside wireless network be implemented directly in the firmware inside wireless network
interface cards [15, 16], well below the layer 3 software within interface cards [15, 16], well below the layer 3 software within
a mobile node. We see great potential in this for DSR running a mobile node. We see great potential in this for DSR running
inside a cloud of mobile nodes around a fixed base station, inside a cloud of mobile nodes around a fixed base station,
where DSR would act to transparently extend the coverage range where DSR would act to transparently extend the coverage range
to these nodes. Mobile nodes that would otherwise be unable to these nodes. Mobile nodes that would otherwise be unable
to communicate with the base station due to factors such as to communicate with the base station due to factors such as
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Appendix C. Implementation and Evaluation Status Appendix C. Implementation and Evaluation Status
The initial design of the DSR protocol, including DSR's basic Route The initial design of the DSR protocol, including DSR's basic Route
Discovery and Route Maintenance mechanisms, was first published in Discovery and Route Maintenance mechanisms, was first published in
December 1994 [15], with significant additional design details and December 1994 [15], with significant additional design details and
initial simulation results published in early 1996 [16]. initial simulation results published in early 1996 [16].
The DSR protocol has been extensively studied since then through The DSR protocol has been extensively studied since then through
additional detailed simulations. In particular, we have implemented additional detailed simulations. In particular, we have implemented
DSR in the ns-2 network simulator [25, 5] and performed extensive DSR in the ns-2 network simulator [26, 5] and performed extensive
simulations of DSR using ns-2 (e.g., [5, 21]). We have also simulations of DSR using ns-2 (e.g., [5, 21]). We have also
conducted evaluations of the different caching strategies in this conducted evaluations of the different caching strategies in this
document [10]. document [10].
We have also implemented the DSR protocol under the FreeBSD 2.2.7 We have also implemented the DSR protocol under the FreeBSD 2.2.7
operating system running on Intel x86 platforms. FreeBSD [9] is operating system running on Intel x86 platforms. FreeBSD [9] is
based on a variety of free software, including 4.4 BSD Lite from the based on a variety of free software, including 4.4 BSD Lite from the
University of California, Berkeley. For the environments in which University of California, Berkeley. For the environments in which
we used it, this implementation is functionally equivalent to the we used it, this implementation is functionally equivalent to the
version of the DSR protocol specified in this document. version of the DSR protocol specified in this document.
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Report [22]. Report [22].
We have since ported this implementation of DSR to FreeBSD 3.3, and We have since ported this implementation of DSR to FreeBSD 3.3, and
we have also added a preliminary version of Quality of Service (QoS) we have also added a preliminary version of Quality of Service (QoS)
support for DSR. A demonstration of this modified version of DSR was support for DSR. A demonstration of this modified version of DSR was
presented in July 2000. These QoS features are not included in this presented in July 2000. These QoS features are not included in this
document, and will be added later in a separate document on top of document, and will be added later in a separate document on top of
the base protocol specified here. the base protocol specified here.
DSR has also been implemented under Linux by Alex Song at the DSR has also been implemented under Linux by Alex Song at the
University of Queensland, Australia [34]. This implementation University of Queensland, Australia [36]. This implementation
supports the Intel x86 PC platform and the Compaq iPAQ. supports the Intel x86 PC platform and the Compaq iPAQ.
The Network and Telecommunications Research Group at Trinity College The Network and Telecommunications Research Group at Trinity College
Dublin have implemented a version of DSR on Windows CE. Dublin have implemented a version of DSR on Windows CE.
Microsoft Research has implemented a version of DSR on Windows XP, Microsoft Research has implemented a version of DSR on Windows XP,
and has used it in testbeds of over 15 nodes. Several machines use and has used it in testbeds of over 15 nodes. Several machines use
this implementation as their primary means of accessing the Internet. this implementation as their primary means of accessing the Internet.
Several other independent groups have also used DSR as a platform for Several other independent groups have also used DSR as a platform for
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A preliminary version of the optional DSR flow state extension was A preliminary version of the optional DSR flow state extension was
implemented in FreeBSD 3.3. A demonstration of this modified version implemented in FreeBSD 3.3. A demonstration of this modified version
of DSR was presented in July 2000. The DSR flow state extension has of DSR was presented in July 2000. The DSR flow state extension has
also been extensively evaluated using simulation [11]. also been extensively evaluated using simulation [11].
Changes from Previous Version of the Draft Changes from Previous Version of the Draft
This appendix briefly lists some of the major changes in this This appendix briefly lists some of the major changes in this
draft relative to the previous version of this same draft, draft relative to the previous version of this same draft,
draft-ietf-manet-dsr-07.txt: draft-ietf-manet-dsr-09.txt:
- Integrated the specification of the DSR flow state extension into - Changed the values used for the Route Request and Route Reply
the main DSR draft. Previously, these had been specified in a options so that they are assigned in a more logical order (Route
separate draft. Request is now 1 and Route Reply is 2, rather than the other way
around).
- Included processing directions for unknown Option Types. - Specification of interaction of DSR with ARP.
- Changed the name of the DSR header to DSR Options header, to - Better integration of multiple network interfaces into the main
clarify it as a separate header type from the DSR Flow State packet processing specification in Section 8.
header.
- Slightly changed the format of the DSR Options header and the DSR - Removal of optimizations for unidirectional links, based on
Flow State header to allow the same IP protocol number to be used special 127.0.0.1 and 127.0.0.2 flags in a Route Request and
for both. The new Flow State Header (F) bit in the two headers Route Reply. These optimizations were not fully specified in
indicates which type of header is being used (the bit is clear in the draft and will be included in future versions of the DSR
a DSR Options header and set in a DSR Flow State header). specification.
- Clarification of rules for IP fragmentation in Section 8.5.
- Revisions to the IANA Considerations section to state that the
DSR Options header and DSR Flow State header can share a single
IP protocol number assignment, and to add of a policy for DSR
options assignments.
- Other general clarification of the specification, based on
feedback received in Area Director review comments.
Acknowledgements Acknowledgements
The protocol described in this document has been designed and The protocol described in this document has been designed and
developed within the Monarch Project, a research project at Rice developed within the Monarch Project, a research project at Rice
University (previously at Carnegie Mellon University) that is University (previously at Carnegie Mellon University) that is
developing adaptive networking protocols and protocol interfaces to developing adaptive networking protocols and protocol interfaces to
allow truly seamless wireless and mobile node networking [17, 33]. allow truly seamless wireless and mobile node networking [17, 35].
The authors would like to acknowledge the substantial contributions The authors would like to acknowledge the substantial contributions
of Josh Broch in helping to design, simulate, and implement the DSR of Josh Broch in helping to design, simulate, and implement the DSR
protocol. We thank him for his contributions to earlier versions of protocol. We thank him for his contributions to earlier versions of
this document. this document.
We would also like to acknowledge the assistance of Robert V. Barron We would also like to acknowledge the assistance of Robert V. Barron
at Carnegie Mellon University. Bob ported our DSR implementation at Carnegie Mellon University. Bob ported our DSR implementation
from FreeBSD 2.2.7 into FreeBSD 3.3. from FreeBSD 2.2.7 into FreeBSD 3.3.
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[23] David A. Maltz, Josh Broch, and David B. Johnson. Quantitative [23] David A. Maltz, Josh Broch, and David B. Johnson. Quantitative
Lessons From a Full-Scale Multi-Hop Wireless Ad Hoc Network Lessons From a Full-Scale Multi-Hop Wireless Ad Hoc Network
Testbed. In Proceedings of the IEEE Wireless Communications and Testbed. In Proceedings of the IEEE Wireless Communications and
Networking Conference, September 2000. Networking Conference, September 2000.
[24] David A. Maltz, Josh Broch, and David B. Johnson. Lessons From [24] David A. Maltz, Josh Broch, and David B. Johnson. Lessons From
a Full-Scale MultiHop Wireless Ad Hoc Network Testbed. IEEE a Full-Scale MultiHop Wireless Ad Hoc Network Testbed. IEEE
Personal Communications, 8(1):8--15, February 2001. Personal Communications, 8(1):8--15, February 2001.
[25] The Network Simulator -- ns-2. Project web page available at [25] Thomas Narten and Harald Tveit Alvestrand. Guidelines for
Writing an IANA Considerations Section in RFCs. RFC 2434,
October 1998.
[26] The Network Simulator -- ns-2. Project web page available at
http://www.isi.edu/nsnam/ns/. http://www.isi.edu/nsnam/ns/.
[26] Panagiotis Papadimitratos and Zygmunt J. Haas. Secure Routing [27] Panagiotis Papadimitratos and Zygmunt J. Haas. Secure Routing
for Mobile Ad Hoc Networks. In SCS Communication Networks and for Mobile Ad Hoc Networks. In SCS Communication Networks and
Distributed Systems Modeling and Simulation Conference (CNDS Distributed Systems Modeling and Simulation Conference (CNDS
2002), January 2002. 2002), January 2002.
[27] Radia Perlman. Interconnections: Bridges and Routers. [28] Charles Perkins. IP Encapsulation within IP. RFC 2003, October
1996.
[29] Radia Perlman. Interconnections: Bridges and Routers.
Addison-Wesley, Reading, Massachusetts, 1992. Addison-Wesley, Reading, Massachusetts, 1992.
[28] David C. Plummer. An Ethernet Address Resolution Protocol: [30] David C. Plummer. An Ethernet Address Resolution Protocol:
Or Converting Network Protocol Addresses to 48.bit Ethernet Or Converting Network Protocol Addresses to 48.bit Ethernet
Addresses for Transmission on Ethernet Hardware. RFC 826, Addresses for Transmission on Ethernet Hardware. RFC 826,
November 1982. November 1982.
[29] J. B. Postel, editor. Internet Control Message Protocol. [31] J. B. Postel, editor. Internet Control Message Protocol.
RFC 792, September 1981. RFC 792, September 1981.
[30] J. B. Postel, editor. Internet Protocol. RFC 791, September [32] J. B. Postel, editor. Internet Protocol. RFC 791, September
1981. 1981.
[31] J. B. Postel, editor. Transmission Control Protocol. RFC 793, [33] J. B. Postel, editor. Transmission Control Protocol. RFC 793,
September 1981. September 1981.
[32] Joyce K. Reynolds and Jon Postel. Assigned Numbers. RFC 1700, [34] Joyce K. Reynolds and Jon Postel. Assigned Numbers. RFC 1700,
October 1994. See also http://www.iana.org/numbers.html. October 1994. See also http://www.iana.org/numbers.html.
[33] Rice University Monarch Project. Monarch Project Home Page. [35] Rice University Monarch Project. Monarch Project Home Page.
Available at http://www.monarch.cs.rice.edu/. Available at http://www.monarch.cs.rice.edu/.
[34] Alex Song. picoNet II: A Wireless Ad Hoc Network for Mobile [36] Alex Song. picoNet II: A Wireless Ad Hoc Network for Mobile
Handheld Devices. Submitted for the degree of Bachelor of Handheld Devices. Submitted for the degree of Bachelor of
Engineering (Honours) in the division of Electrical Engineering, Engineering (Honours) in the division of Electrical Engineering,
Department of Information Technology and Electrical Engineering, Department of Information Technology and Electrical Engineering,
University of Queensland, Australia, October 2001. Available at University of Queensland, Australia, October 2001. Available at
http://student.uq.edu.au/~s369677/main.html. http://student.uq.edu.au/~s369677/main.html.
[35] Paul Turner. NetWare Communications Processes. NetWare [37] Paul Turner. NetWare Communications Processes. NetWare
Application Notes, Novell Research, pages 25--91, September Application Notes, Novell Research, pages 25--91, September
1990. 1990.
[36] Gary R. Wright and W. Richard Stevens. TCP/IP Illustrated, [38] Gary R. Wright and W. Richard Stevens. TCP/IP Illustrated,
Volume 2: The Implementation. Addison-Wesley, Reading, Volume 2: The Implementation. Addison-Wesley, Reading,
Massachusetts, 1995. Massachusetts, 1995.
Chair's Address Chair's Address
The MANET Working Group can be contacted via its current chairs: The MANET Working Group can be contacted via its current chairs:
M. Scott Corson Phone: +1 908 947-7033 M. Scott Corson Phone: +1 908 947-7033
Flarion Technologies, Inc. Email: corson@flarion.com Flarion Technologies, Inc. Email: corson@flarion.com
Bedminster One Bedminster One
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