draft-ietf-mip4-dynamic-assignment-03.txt   draft-ietf-mip4-dynamic-assignment-04.txt 
Mobile IP Working Group Milind Kulkarni Mobile IP Working Group Milind Kulkarni
INTERNET-DRAFT Alpesh Patel INTERNET-DRAFT Alpesh Patel
Category: Standards Track Kent Leung Category: Standards Track Kent Leung
Date : 28 September 2004 Cisco Systems Inc. Date : 28 May 2005 Cisco Systems Inc.
Mobile IPv4 Dynamic Home Agent Assignment Mobile IPv4 Dynamic Home Agent Assignment
draft-ietf-mip4-dynamic-assignment-03.txt draft-ietf-mip4-dynamic-assignment-04.txt
Status of this Memo Status of this Memo
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and any of which I become aware will be disclosed, in accordance with have been or will be disclosed, and any of which he or she becomes
RFC 3668. aware will be disclosed, in accordance with Section 6 of BCP 79.
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2005).
Abstract Abstract
Mobile IPv4 [1] uses the Home Agent (HA) to anchor sessions of a Mobile IPv4 [1] uses the Home Agent (HA) to anchor sessions of a
roaming Mobile Node (MN). This draft proposes a messaging mechanism roaming Mobile Node (MN). This draft proposes a messaging mechanism
for dynamic home agent assignment and HA redirection. The goal is to for dynamic home agent assignment and HA redirection. The goal is to
provide a mechanism to assign an optimal HA for a Mobile IP session provide a mechanism to assign an optimal HA for a Mobile IP session
while allowing any suitable method for HA selection. while allowing any suitable method for HA selection.
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Table of Contents Table of Contents
1. Introduction................................................3 1. Introduction................................................3
2. Requirements Terminology....................................3 2. Requirements Terminology....................................3
3. Problem Statement...........................................4 3. Problem Statement...........................................4
3.1 Scope.......................................................5 3.1 Scope.......................................................5
3.2 Dynamic Home Agent Discovery in Mobile IPv4.................5 3.2 Dynamic Home Agent Discovery in Mobile IPv4.................5
3.3 NAI usage and dynamic HA assignment.........................5 3.3 NAI usage and dynamic HA assignment.........................5
3.4 Dynamic HA Extension........................................6 3.4 Dynamic HA Extension........................................6
3.4.1 Requested HA Extension....................................6 3.4.1 Requested HA Extension....................................6
3.4.2 Redirected HA Extension...................................7 3.4.2 Redirected HA Extension...................................7
4. Messaging mechanism for dynamic HA assignment/redirection...7 4. Messaging mechanism for dynamic HA assignment/redirection...7
4.1 Messaging for dynamic HA assignment.........................7 4.1 Messaging for dynamic HA assignment.........................7
4.1.1 Example with Message Flow Diagram.........................8 4.1.1 Example with Message Flow Diagram.........................8
4.2 Messaging for HA redirection................................9 4.2 Messaging for HA redirection...............................10
4.2.1 Example with Message Flow Diagram........................10 4.2.1 Example with Message Flow Diagram........................10
5. Mobility Agent Considerations..............................12 5. Mobility Agent Considerations..............................12
5.1 Mobile Node Considerations.................................12 5.1 Mobile Node Considerations.................................12
5.1.1 MN using FA CoA..........................................12 5.1.1 MN using FA CoA..........................................13
5.1.2 MN using Collocated CoA..................................13 5.1.2 MN using Co-located CoA..................................13
5.1.3 Refreshing Assigned HA Address on Mobile Node............13 5.1.3 Refreshing Assigned HA Address on Mobile Node............14
5.2 Foreign Agent Considerations...............................14 5.2 Foreign Agent Considerations...............................14
5.3 Home Agent Considerations..................................14 5.3 Home Agent Considerations..................................15
5.3.1 Assigned Home Agent Considerations.......................15 5.3.1 Assigned Home Agent Considerations.......................15
6. Requested Home Agent Selection.............................16 6. Requested Home Agent Selection.............................17
7. Error Values...............................................17 7. Error Values...............................................18
8. IANA Considerations........................................18 8. IANA Considerations........................................18
9. Security Considerations....................................18 9. Security Considerations....................................18
10. Backward Compatibility Considerations.....................19 10. Backward Compatibility Considerations.....................19
11. Change Log from previous versions.........................19 11. Change Log from previous versions.........................20
12. Acknowledgements..........................................20 12. Acknowledgements..........................................21
13. Normative References......................................20 13. Normative References......................................21
Authors' Addresses.............................................20 Authors' Addresses.............................................21
Intellectual Property Statement................................21 Intellectual Property Statement................................22
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1. Introduction 1. Introduction
This document adds to the Mobile IP protocol [1], by proposing a This document adds to the Mobile IP protocol [1], by proposing a
messaging mechanism for dynamic home agent assignment and home agent messaging mechanism for dynamic home agent assignment and home agent
redirection during initial registration. The goal is to assign an redirection during initial registration. The goal is to assign an
optimal HA for a Mobile IP session. The mobile node MUST use the optimal HA for a Mobile IP session. The mobile node MUST use the
Network Access Identifier (NAI) extension [2] when requesting a Network Access Identifier (NAI) extension [2] when requesting a
dynamically assigned HA. dynamically assigned HA.
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The Mobile IP related terminology described in RFC 3344 [1] is used The Mobile IP related terminology described in RFC 3344 [1] is used
in this document. In addition, the following terms are used: in this document. In addition, the following terms are used:
ALL-ZERO-ONE-ADDR: IP address 0.0.0.0 or 255.255.255.255. An ALL-ZERO-ONE-ADDR: IP address 0.0.0.0 or 255.255.255.255. An
address of 255.255.255.255 indicates a preference address of 255.255.255.255 indicates a preference
for an HA in the home domain. An address of for an HA in the home domain. An address of
0.0.0.0 indicates no preference for home vs. 0.0.0.0 indicates no preference for home vs.
visited domain. visited domain.
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Requested HA: Destination IP address of Home Agent that the Requested HA: Destination IP address of Home Agent that the
Registration Request is sent to. Must be a Registration Request is sent to. Must be a
unicast IP address. This address can be unicast IP address. This address can be
obtained as described in section 6. obtained as described in section 6.
Note that this specification defines a new Note that this specification defines a new
"Requested HA Extension" in section 3.4, which "Requested HA Extension" in section 3.4, which
is different from the term "Requested HA". is different from the term "Requested HA".
Assigned HA: The HA that accepts an MN's Registration Request Assigned HA: The HA that accepts an MN's Registration Request
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DHCP: Dynamic Host Configuration Protocol. DHCP: Dynamic Host Configuration Protocol.
MN: Mobile Node as defined in Mobile IPv4 [1]. MN: Mobile Node as defined in Mobile IPv4 [1].
HA: Home Agent as defined in Mobile IPv4 [1]. HA: Home Agent as defined in Mobile IPv4 [1].
FA: Foreign Agent as defined in Mobile IPv4 [1]. FA: Foreign Agent as defined in Mobile IPv4 [1].
CoA: Care of Address. CoA: Care of Address.
CCoA: Collocated Care of Address. CCoA: Co-located Care of Address.
MN HoA: Mobile Node's Home Address. MN HoA: Mobile Node's Home Address.
NAI: Network Access Identifier [2]. NAI: Network Access Identifier [2].
Src IP: Source IP address of the packet. Src IP: Source IP address of the packet.
Dest IP: Destination IP address of the packet. Dest IP: Destination IP address of the packet.
3. Problem Statement 3. Problem Statement
The Mobile IPv4 NAI Extension for IPv4 [2] introduced the concept of The Mobile IPv4 NAI Extension for IPv4 [2] introduced the concept of
identifying a MN by the NAI and enabling dynamic home address identifying a MN by the NAI and enabling dynamic home address
assignment. When the home address is dynamically assigned, it is assignment. When the home address is dynamically assigned, it is
desirable to discover the Home Agent dynamically or inform the MN desirable to discover the Home Agent dynamically or inform the MN
about an optimal HA to use for a multitude of reasons, such as: about an optimal HA to use for a multitude of reasons, such as:
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- If the distance between the visited network and the home network of - If the distance between the visited network and the home network of
the mobile node is large, the signaling delay for these registrations the mobile node is large, the signaling delay for these registrations
may be long. In such a case the MN will be anchored to its distant may be long. In such a case the MN will be anchored to its distant
home agent, resulting in tunneled traffic traveling a long distance home agent, resulting in tunneled traffic traveling a long distance
between home agent and the mobile node. When a Mobile IP session between home agent and the mobile node. When a Mobile IP session
initiates, if the mobile node can be assigned a home agent that is initiates, if the mobile node can be assigned a home agent that is
close to the mobile node it can drastically reduce the latency close to the mobile node it can drastically reduce the latency
between the home agent and mobile node. between the home agent and mobile node.
- In a large scale Mobile IP deployment, it is cumbersome to - In a large scale Mobile IP deployment, it is cumbersome to
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security association between the MN and HA, and it can either be security association between the MN and HA, and it can either be
statically preconfigured or dynamically distributed using other statically preconfigured or dynamically distributed using other
mechanisms [7]. mechanisms [7].
The draft introduces the terms Requested/Assigned/Redirected HA The draft introduces the terms Requested/Assigned/Redirected HA
(section 6). The discovery of candidate HA addresses for insertion (section 6). The discovery of candidate HA addresses for insertion
into the Redirected HA Extension can be accomplished through various into the Redirected HA Extension can be accomplished through various
means which are network and/or deployment specific and hence are means which are network and/or deployment specific and hence are
outside the scope of this specification. outside the scope of this specification.
The MN MAY request dynamic HA assignment when it is not aware of any
HA address and even when it is aware of at least one HA address.
3.2 Dynamic Home Agent Discovery in Mobile IPv4 3.2 Dynamic Home Agent Discovery in Mobile IPv4
Mobile IPv4 [1] specifies the mechanism for discovering the mobile Mobile IPv4 [1] specifies the mechanism for discovering the mobile
node's home agent using subnet-directed broadcast IP address in the node's home agent using subnet-directed broadcast IP address in the
home agent field of the Registration Request. This mechanism was home agent field of the Registration Request. This mechanism was
designed for mobile nodes with a static home address and subnet designed for mobile nodes with a static home address and subnet
prefix, anchored on fixed home network. However, using subnet prefix, anchored on fixed home network. However, using subnet
directed broadcast as the destination IP address of the Registration directed broadcast as the destination IP address of the Registration
Request, it is unlikely that the Registration Request will reach the Request, it is unlikely that the Registration Request will reach the
home subnet because routers will drop these packets by default. See home subnet because routers will drop these packets by default. See
CERT Advisory CA-1998-01 Smurf IP Denial-of-Service Attacks [3]. CERT Advisory CA-1998-01 Smurf IP Denial-of-Service Attacks [3].
3.3 NAI usage and dynamic HA assignment 3.3 NAI usage and dynamic HA assignment
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The Mobile IPv4 NAI Extension for IPv4 [2] introduced the The Mobile IPv4 NAI Extension for IPv4 [2] introduced the
concept of identifying a MN by the NAI and enabling dynamic concept of identifying a MN by the NAI and enabling dynamic
home address assignment. This document mandates that while home address assignment. This document requires that while
using dynamic HA assignment, MN MUST use the NAI and obtain a home using dynamic HA assignment, MN MUST use the NAI and obtain a home
address. MN can still suggest a static home address in the address. MN can still suggest a static home address in the
Registration Request, but must take the address in the Registration Registration Request, but must take the address in the Registration
Reply as the home address for the session. This is compatible with Reply as the home address for the session. This is compatible with
the procedures documented in the NAI specification [2]. the procedures documented in the NAI specification [2].
3.4 Dynamic HA Extension 3.4 Dynamic HA Extension
The Dynamic HA Extension, shown in figure 1, contains the address of The Dynamic HA Extension, shown in figure 1, contains the address of
the HA. This is a generic extension and can be used in Registration the HA. This is a generic extension and can be used in Registration
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3.4.1 Requested HA Extension 3.4.1 Requested HA Extension
The Requested HA Extension is a Dynamic HA Extension of subtype 1. The Requested HA Extension is a Dynamic HA Extension of subtype 1.
The MN may include the Requested HA Extension in the registration The MN may include the Requested HA Extension in the registration
request as a hint to the network where it wishes to be anchored. request as a hint to the network where it wishes to be anchored.
This extension contains the address of the HA. A valid unicast IP This extension contains the address of the HA. A valid unicast IP
address MUST be used as HA address in this extension. address MUST be used as HA address in this extension.
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In absence of an FA, the RRQ is forwarded to this HA. In presence of In absence of an FA, the RRQ is forwarded to this HA. In presence of
an FA, the FA MUST forward RRQ to the HA address in this extension. an FA, the FA MUST forward RRQ to the HA address in this extension.
3.4.2 Redirected HA Extension 3.4.2 Redirected HA Extension
The Redirected HA Extension is a Dynamic HA Extension of subtype 2. The Redirected HA Extension is a Dynamic HA Extension of subtype 2.
The Redirected HA Extension contains the address of the HA where the The Redirected HA Extension contains the address of the HA where the
MN should attempt the next registration. The HA receiving a MN should attempt the next registration. The HA receiving a
Registration Request can suggest an alternate HA and, if so, the Registration Request can suggest an alternate HA and, if so, the
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4. Messaging mechanism for dynamic HA assignment/redirection 4. Messaging mechanism for dynamic HA assignment/redirection
This specification presents two alternatives for home agent This specification presents two alternatives for home agent
assignment. The two alternatives are: assignment. The two alternatives are:
(a) Dynamic HA assignment (described in section 4.1) and (a) Dynamic HA assignment (described in section 4.1) and
(b) HA redirection (described in section 4.2). (b) HA redirection (described in section 4.2).
4.1 Messaging for dynamic HA assignment 4.1 Messaging for dynamic HA assignment
The following sequence of events occurs when the Requested HA accepts The following sequence of events occur when the MN requests dynamic
the Registration Request and returns a Registration Reply to the Home Agent assignment:
mobile node.
1. The MN sets the Home Agent address field in the Registration 1. The MN sets the Home Agent address field in the Registration
Request to ALL-ZERO-ONE-ADDR. If the MN is aware of a desired HA Request to ALL-ZERO-ONE-ADDR. If the MN is aware of a desired HA
address, it can add that address in the Requested HA Extension in address, it can add that address in the Requested HA Extension in
the Registration Request. the Registration Request. If the HA does not support the
2. The MN (if using collocated CoA and registering directly with the Requested HA Extension, see step 2 below.
2. This step is applicable, in lieu of step 1, for a MN that is
aware of the HA address and desires dynamic HA assignment. Also,
the MN follows this (when aware of a HA address) when it
discovers a legacy FA in the path or if the known HA does not
support the Requested HA Extension (see section 10).
The MN sets the Home Agent address field in the Registration
Request to the HA address (instead of setting it to ALL-ZERO-ONE-
ADDR). The MN also adds the same HA address in the Requested HA
Extension in the Registration Request.
3. The MN (if using co-located CoA and registering directly with the
HA) or the FA (if the MN is registering via the FA) sends the HA) or the FA (if the MN is registering via the FA) sends the
Registration Request to the "Requested HA". If the Requested HA Registration Request to the "Requested HA". If the Requested HA
Extension is present, Requested HA is specified in the "HA Extension is present, Requested HA is specified in the "HA
Address" of this extension. Address" of this extension.
3. The "Requested HA" is the home agent that processes the
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Per section 10, in case of a legacy FA, legacy FA forwards the
Registration Request to the address in the HA field of the
Request (thus, MN uses step 2 above in case of legacy FA instead
of step 1).
4. The "Requested HA" is the home agent that processes the
Registration Request in accordance with Mobile IPv4 [1] and as Registration Request in accordance with Mobile IPv4 [1] and as
per the specification in this document. It creates mobility per the specification in this document. It creates mobility
binding for successful Registration Request. It also sends a binding for successful Registration Request. It also sends a
Registration Reply to the MN. Registration Reply to the MN.
4. The MN obtains an "Assigned HA" address from the HA field in the
5. The MN obtains an "Assigned HA" address from the HA field in the
successful Registration Reply and uses it for the remainder of successful Registration Reply and uses it for the remainder of
the session. (Note that the "Assigned HA" will be same as the the session. (Note that the "Assigned HA" will be same as the
"Requested HA"). "Requested HA").
5. Subsequent Registration Request messages for renewal are sent to
6. Subsequent Registration Request messages for renewal are sent to
the Assigned HA. the Assigned HA.
Section 5.3.1 describes the Assigned HA in detail. Some ideas on how Section 5.3.1 describes the Assigned HA in detail. Some ideas on how
to select the Requested HA are briefly covered in section 6. to select the Requested HA are briefly covered in section 6.
4.1.1 Example with Message Flow Diagram 4.1.1 Example with Message Flow Diagram
Detailed explanation of this alternative is best described with the Detailed explanation of this alternative is best described with the
help of a message flow diagram and description. help of a message flow diagram and description.
Figure 2 shows one specific example of a Mobile Node using an FA- Figure 2 shows one specific example of a Mobile Node using an FA-
located Care of Address (FA CoA). located Care of Address (FA CoA) and FA understands the Requested HA
Extension per this specification.
Other scenarios such as when the mobile node uses a collocated care Other scenarios such as when the mobile node uses a co-located care
of address are not described below, but the behavior is similar. of address and presence of a legacy HA or FA are not described below,
but the behavior is similar.
MN FA Requested/Assigned HA MN FA Requested/Assigned HA
| 1 | | | 1 | |
|------------>| 2 | |------------>| 2 |
| |--------------->| | |--------------->|
| | | | | |
| | | | | |
| | 3 | | | 3 |
| 4 |<---------------| | 4 |<---------------|
|<------------| | |<------------| |
| | | | | |
| | 5 | | | 5 |
|----------------------------->| |----------------------------->|
| | | | | |
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Figure 2: Example message flow for dynamic HA assignment Figure 2: Example message flow for dynamic HA assignment
1. The MN sets the Home Agent address field in the Registration 1. The MN sets the Home Agent address field in the Registration
Request to ALL-ZERO-ONE-ADDR. Since the MN is using FA CoA in this Request to ALL-ZERO-ONE-ADDR. Since the MN is using FA CoA in this
example, it sends the Registration Request to the FA. The example, it sends the Registration Request to the FA. The
Registration Request is formatted as follows: Registration Request is formatted as follows:
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
| MN | FA | | ALL-ZERO-ONE-ADDR |FA CoA | | MN | FA | | ALL-ZERO-ONE-ADDR |FA CoA |
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| HA | the RRQ | | | | | HA | the RRQ | | | |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
4. The FA relays the Registration Reply to the MN, as follows. 4. The FA relays the Registration Reply to the MN, as follows.
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
| FA | MN | | Assigned HA |FA CoA/| | FA | MN | | Assigned HA |FA CoA/|
+-----------------------------------------------------------+ +-----------------------------------------------------------+
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5. The MN obtains the Assigned HA address from the HA field in the 5. The MN obtains the Assigned HA address from the HA field in the
successful Registration Reply and uses it for the remainder of the successful Registration Reply and uses it for the remainder of the
session. The MN sends subsequent Re-Registration or De-Registration session. The MN sends subsequent Re-Registration or De-Registration
Requests for the remainder session directly to the Assigned HA. Note Requests for the remainder session directly to the Assigned HA. Note
that the Assigned HA is the same as the Requested HA. that the Assigned HA is the same as the Requested HA.
4.2 Messaging for HA redirection 4.2 Messaging for HA redirection
This section describes the events that occur when the Requested HA This section describes the events that occur when the Requested HA
does not accept the Registration Request and redirects the mobile does not accept the Registration Request and redirects the mobile
node to another HA (aka Redirected HA) instead. node to another HA (aka Redirected HA) instead. This behavior is not
exhibited by a legacy HA and so is not referred in the description
below. In presence of a legacy FA, please refer to section 4.1 for
the specific field in the Registration Request.
1. The MN sets the Home Agent address field in the Registration 1. The MN sets the Home Agent address field in the Registration
Request to ALL-ZERO-ONE-ADDR. Request to ALL-ZERO-ONE-ADDR.
2. The MN (if using collocated CoA and registering directly with the 2. The MN (if using co-located CoA and registering directly with the
HA) or FA (if the MN is registering via the FA) sends the HA) or FA (if the MN is registering via the FA) sends the
Registration Request to the "Requested HA". If the MN is aware of Registration Request to the "Requested HA". If the MN is aware of
an HA address, it can add that address in the Requested HA an HA address, it can add that address in the Requested HA
Extension in Registration Request. Extension in Registration Request.
3. When the HA receives the Registration Request, if the HA field is 3. When the HA receives the Registration Request, if the HA field is
set to ALL-ZERO-ONE-ADDR, the HA may reject the request with Reply set to ALL-ZERO-ONE-ADDR, the HA may reject the request with Reply
code REDIRECT-HA-REQ and suggest an alternate HA. code REDIRECT-HA-REQ and suggest an alternate HA.
The HA may reject the Request for a number of reasons, which are The HA may reject the Request for a number of reasons, which are
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specified in Redirected HA Extension. The presence of this specified in Redirected HA Extension. The presence of this
extension is mandatory when the reply code is set to REDIRECT-HA- extension is mandatory when the reply code is set to REDIRECT-HA-
REQ. HA sends the Reply to the FA/MN. REQ. HA sends the Reply to the FA/MN.
4. FA sends the Reply to the MN. 4. FA sends the Reply to the MN.
5. If the error code is set to REDIRECT-HA-REQ, MN obtains the HA 5. If the error code is set to REDIRECT-HA-REQ, MN obtains the HA
address from Redirected HA Extension. The MN then sends a address from Redirected HA Extension. The MN then sends a
Registration Request to Redirected HA, unless it has already Registration Request to Redirected HA, unless it has already
received a redirection response from this HA while processing this received a redirection response from this HA while processing this
Registration Request. Registration Request. The MN may choose to add Requested HA
extension in this new Registration Request.
4.2.1 Example with Message Flow Diagram 4.2.1 Example with Message Flow Diagram
Figure 3 shows one specific example of a Mobile Node using FA-located Figure 3 shows one specific example of a Mobile Node using FA-located
Care of Address. Care of Address, where the FA is not a legacy FA.
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MN FA Requested HA Redirected HA MN FA Requested HA Redirected HA
| 1 | | | | 1 | | |
|------------>| 2 | | |------------>| 2 | |
| |--------------->| | | |--------------->| |
| | | | | | | |
| | | | | | | |
| | 3 | | | | 3 | |
| 4 |<---------------| | | 4 |<---------------| |
|<------------| | | |<------------| | |
| | | | | | | |
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| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
| FA |Requested HA| | ALL-ZERO-ONE-ADDR |FA CoA | | FA |Requested HA| | ALL-ZERO-ONE-ADDR |FA CoA |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
3. The HA processes the Registration Request in accordance with 3. The HA processes the Registration Request in accordance with
Mobile IPv4 [1] and the messaging defined in this specification. If Mobile IPv4 [1] and the messaging defined in this specification. If
the registration is successful, but local configuration/ the registration is successful, but local configuration/
administrative policy etc. directs HA to refer the MN to another HA, administrative policy etc. directs HA to refer the MN to another HA,
the HA rejects the Request with error code REDIRECT-HA-REQ. The HA the HA rejects the Request with error code REDIRECT-HA-REQ. The HA
fills in the address of the Redirected HA in the Redirected HA fills in the address of the Redirected HA in the Redirected HA
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Extension. The HA then sends Registration Reply reject to the FA, Extension. The HA then sends Registration Reply reject to the FA,
which is formatted as follows: which is formatted as follows:
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
| | Src IP of | | HA |FA CoA | | | Src IP of | | HA |FA CoA |
| HA | the RRQ | | | | | HA | the RRQ | | | |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Redirected HA Extension ... | | Redirected HA Extension ... |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
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| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
| FA | MN | | HA |FA CoA/| | FA | MN | | HA |FA CoA/|
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Redirected HA Extension ... | | Redirected HA Extension ... |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
5. If the MN can authenticate the Reply, the MN extracts the HA 5. If the MN can authenticate the Reply, the MN extracts the HA
address from the Redirected HA Extension. The MN then sends a address from the Redirected HA Extension. The MN then sends a
Registration Request to the Redirected HA, unless it has already Registration Request to the Redirected HA, unless it has already
received a redirection response from that HA while processing the received a redirection response from that HA while processing the
Registration Request. Registration Request. The MN may choose to add Requested HA
extension in this new Registration Request.
5. Mobility Agent Considerations 5. Mobility Agent Considerations
The following sections describe the behavior of each mobility agent The following sections describe the behavior of each mobility agent
in detail. in detail.
5.1 Mobile Node Considerations 5.1 Mobile Node Considerations
The mobile node MUST use the NAI extension for home address The mobile node MUST use the NAI extension for home address
assignment when using the messaging mechanism in this document. assignment when using the messaging mechanism in this document.
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While dynamic HA assignment is in progress and the MN has not While dynamic HA assignment is in progress and the MN has not
successfully anchored at a Home Agent, the MN MUST set the Home Agent successfully anchored at a Home Agent, the MN MUST set the Home Agent
field in the Registration Request to an ALL-ZERO-ONE-ADDR, which is field in the Registration Request to an ALL-ZERO-ONE-ADDR, which is
either 255.255.255.255 or 0.0.0.0. either 255.255.255.255 or 0.0.0.0.
The Registration Request MUST be protected by a valid authenticator The Registration Request MUST be protected by a valid authenticator
as specified in Mobile IPv4 [1] or Mobile IPv4 Challenge/Response as specified in Mobile IPv4 [1] or Mobile IPv4 Challenge/Response
Extensions [5]. Configuring security associations is deployment Extensions [5]. Configuring security associations is deployment
specific and hence outside the scope of this specification. The specific and hence outside the scope of this specification. The
security associations between a MN and an individual HA may also be security associations between a MN and an individual HA may also be
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dynamically derived during the dynamic HA assignment, based on a dynamically derived during the dynamic HA assignment, based on a
shared secret between MN and AAA infrastructure [7]. shared secret between MN and AAA infrastructure [7].
The mobile node MUST maintain the remaining Mobile IP session with The mobile node MUST maintain the remaining Mobile IP session with
the Assigned HA. the Assigned HA.
The following sections describe MN behavior in FA CoA mode and The following sections describe MN behavior in FA CoA mode and co-
collocated CoA mode. located CoA mode.
5.1.1 MN using FA CoA 5.1.1 MN using FA CoA
When a mobile node initiates a Mobile IP session requesting dynamic When a mobile node initiates a Mobile IP session requesting dynamic
HA assignment, it MUST set the home agent address field in the HA assignment, it MUST set the home agent address field in the
Registration Request to ALL-ZERO-ONE-ADDR. The destination IP Registration Request to ALL-ZERO-ONE-ADDR. The destination IP
address of the Registration Request is the FA. The FA will determine address of the Registration Request is the FA. The FA will determine
the Requested HA and forward the Registration Request to the the Requested HA and forward the Registration Request to the
Requested HA. Registration Request processing takes place on the Requested HA. Registration Request processing takes place on the
Requested HA as per the specification in this draft. Requested HA as per the specification in this draft.
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If a Registration Reply is received with code REDIRECT-HA-REQ, the MN If a Registration Reply is received with code REDIRECT-HA-REQ, the MN
MUST authenticate the Reply based on HA address in HA field of Reply MUST authenticate the Reply based on HA address in HA field of Reply
and attempt Registration with the HA address specified in the and attempt Registration with the HA address specified in the
Redirected HA Extension. The MN MUST put the Redirected HA address Redirected HA Extension. The MN MUST put the Redirected HA address
as the Requested HA Extension of the new Registration Request. as the Requested HA Extension of the new Registration Request.
In some cases, for the first Registration Request the MN may want to In some cases, for the first Registration Request the MN may want to
hint to the network to be anchored at a specific HA. The MN SHOULD hint to the network to be anchored at a specific HA. The MN SHOULD
put that address in the HA address of the Requested HA Extension. put that address in the HA address of the Requested HA Extension.
If the Registration Request contains the Requested HA Extension, the 5.1.2 MN using Co-located CoA
HA address in that extension MUST match the destination IP of the
Request.
5.1.2 MN using Collocated CoA
An MN in collocated CoA mode requesting dynamic HA assignment MUST An MN in co-located CoA mode requesting dynamic HA assignment MUST
set the home agent address field in the Registration Request to ALL- set the home agent address field in the Registration Request to ALL-
ZERO-ONE-ADDR. The destination IP address of the Registration ZERO-ONE-ADDR. The destination IP address of the Registration
Request is the Requested HA. Some ideas on how to select a Requested Request is the Requested HA. Some ideas on how to select a Requested
HA are briefly covered in section 6. HA are briefly covered in section 6.
If a successful Reply is received, the MN obtains the Assigned HA If a successful Reply is received, the MN obtains the Assigned HA
address from the successful Registration Reply. The Assigned HA will address from the successful Registration Reply. The Assigned HA will
be the same as Requested HA to which the Registration Request was be the same as Requested HA to which the Registration Request was
sent. The MN MUST cache the Assigned HA address for the length of sent. The MN MUST cache the Assigned HA address for the length of
the Mobile IP session. The mobile node then MUST use this previously the Mobile IP session. The mobile node then MUST use this previously
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cached Assigned HA address as the home agent address in subsequent cached Assigned HA address as the home agent address in subsequent
re-registration and de-registration request(s). This will make sure re-registration and de-registration request(s). This will make sure
that for the duration of the Mobile IP session, the mobile node will that for the duration of the Mobile IP session, the mobile node will
always be anchored to the assigned home agent with which it was always be anchored to the assigned home agent with which it was
initially registered. initially registered.
If a Registration Reply is received with code REDIRECT-HA-REQ, the MN If a Registration Reply is received with code REDIRECT-HA-REQ, the MN
MUST authenticate the Reply based on HA address in HA field of Reply MUST authenticate the Reply based on HA address in HA field of Reply
and attempt Registration with the HA address specified in the and attempt Registration with the HA address specified in the
Redirected HA Extension. The MN MUST put the Redirected HA in the Redirected HA Extension. The MN MUST put the Redirected HA in the
Requested HA Extension of the new Registration Request. Requested HA Extension of the new Registration Request.
In some cases, for the first Registration Request MN may want to hint In some cases, for the first Registration Request MN may want to hint
to the network to be anchored at a specific HA and the MN SHOULD put to the network to be anchored at a specific HA and the MN SHOULD put
that address in the HA address of the Requested HA Extension. that address in the HA address of the Requested HA Extension.
While requesting dynamic HA assignment and registering directly with While requesting dynamic HA assignment and registering directly with
an HA, the Requested HA Extension MUST be included and MUST contain an HA, the Requested HA Extension MUST be included and MUST contain
the address of the HA to which the Registration Request is sent. the address of the HA to which the Registration Request is sent.
When using collocated CoA but registering via an FA the Requested HA When using co-located CoA but registering via a legacy FA, the HA
Extension MAY be present or MAY be omitted. field in Reqistration Request may be set to Requested HA.
If the Registration Request contains the Requested HA Extension, the
HA address in that extension MUST match the destination IP of the
Request.
5.1.3 Refreshing Assigned HA Address on Mobile Node 5.1.3 Refreshing Assigned HA Address on Mobile Node
When the Mobile IP session terminates, the mobile node MAY clear the When the Mobile IP session terminates, the mobile node MAY clear the
Assigned HA address cached as the home agent address. It MAY request Assigned HA address cached as the home agent address. It MAY request
a new HA address for the new Mobile IP session by not including the a new HA address for the new Mobile IP session by not including the
Requested HA Extension. The advantage of this approach is that the Requested HA Extension. The advantage of this approach is that the
mobile node will be always anchored to an optimal home agent from mobile node will be always anchored to an optimal home agent from
where it initiated the Mobile IP session. where it initiated the Mobile IP session.
Alternately, the MN may save the Assigned HA address and use it in Alternately, the MN may save the Assigned HA address and use it in
the Requested HA Extension along with ALL-ZERO-ONE-ADDR HA address in the Requested HA Extension along with ALL-ZERO-ONE-ADDR HA address in
Registration Request for a new Mobile IP session. Registration Request for a new Mobile IP session.
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Requested HA Extension. The advantage of this approach is that the Requested HA Extension. The advantage of this approach is that the
mobile node will be always anchored to an optimal home agent from mobile node will be always anchored to an optimal home agent from
where it initiated the Mobile IP session. where it initiated the Mobile IP session.
Alternately, the MN may save the Assigned HA address and use it in Alternately, the MN may save the Assigned HA address and use it in
the Requested HA Extension along with ALL-ZERO-ONE-ADDR HA address in the Requested HA Extension along with ALL-ZERO-ONE-ADDR HA address in
Registration Request for a new Mobile IP session. Registration Request for a new Mobile IP session.
5.2 Foreign Agent Considerations 5.2 Foreign Agent Considerations
When the mobile node is using FA CoA it always registers via the FA. When the mobile node is using a FA CoA it always registers via the
When the MN is using a collocated CoA it may register using an FA or FA. When the MN is using a co-located CoA it may register through a
it may register directly with an HA, unless the R bit is set in the FA or it may register directly with an HA, unless the R bit is set in
FA's agent advertisement, in which case it always registers with the the FA's agent advertisement, in which case it always registers
FA. through the FA.
When the FA receives a Registration Request with HA address field set When the FA receives a Registration Request with HA address field set
to ALL-ZERO-ONE-ADDR that doesn't contain the Requested HA Extension, to ALL-ZERO-ONE-ADDR that doesn't contain the Requested HA Extension,
the FA obtains the Requested HA address to forward the Registration the FA obtains the Requested HA address to forward the Registration
Request using means outside the scope of this specification. Some Request using means outside the scope of this specification. Some
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ideas on how to select a Requested HA are briefly covered in section ideas on how to select a Requested HA are briefly covered in section
6. 6.
If the FA cannot obtain the Requested HA to which to forward a If the FA cannot obtain the Requested HA to which to forward a
Registration Request from MN, it MUST reject request with error code Registration Request from MN, it MUST reject request with error code
NONZERO-HA-REQD. NONZERO-HA-REQD.
If the MN has included the Requested HA Extension, the FA MUST If the MN has included the Requested HA Extension, the FA MUST
forward Registration Request to the address in this extension. If forward Registration Request to the address in this extension. If
the HA address in this extension is not a routable unicast address, the HA address in this extension is not a routable unicast address,
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5.3.1 Assigned Home Agent Considerations 5.3.1 Assigned Home Agent Considerations
The HA that processes the incoming Registration Request fully in The HA that processes the incoming Registration Request fully in
accordance with Mobile IPv4 [1] and this specification becomes the accordance with Mobile IPv4 [1] and this specification becomes the
Assigned HA. The Registration Request terminates at the Assigned HA. Assigned HA. The Registration Request terminates at the Assigned HA.
The Assigned HA creates one mobility binding per MN and sends The Assigned HA creates one mobility binding per MN and sends
Registration Reply to the MN by copying its address in the home agent Registration Reply to the MN by copying its address in the home agent
field and as the source IP address of the Reply. field and as the source IP address of the Reply.
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The following table summarizes the behavior of the Assigned HA, based The following table summarizes the behavior of the Assigned HA, based
on the value of the destination IP address and Home Agent field of on the value of the destination IP address and Home Agent field of
the Registration Request. the Registration Request.
Dest IP Addr HA field Processing at Assigned HA Dest IP Addr HA field Processing at Assigned HA
------------ ------------ ---------------------------------- ------------ ------------ ----------------------------------
Unicast non-unicast Mobile IPv4 [1]: There is no change Unicast non-unicast Mobile IPv4 [1]: There is no change
in handling for this case from in handling for this case from
(Must be Mobile IPv4. It is mentioned here (Must be Mobile IPv4. It is mentioned here
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specify any new behavior for the case where the HA receives a subnet specify any new behavior for the case where the HA receives a subnet
directed broadcast Registration Request as specified in section directed broadcast Registration Request as specified in section
3.8.2.1 of the Mobile IPv4 specification [1]. Although the Home 3.8.2.1 of the Mobile IPv4 specification [1]. Although the Home
Agent field in the Registration Request is not a unicast address, the Agent field in the Registration Request is not a unicast address, the
destination IP address is a unicast address. This avoids the destination IP address is a unicast address. This avoids the
problem associated with subnet-directed broadcast destination IP problem associated with subnet-directed broadcast destination IP
address that may result in multiple HAs responding. Thus, there is address that may result in multiple HAs responding. Thus, there is
no need to deny the registration as stated in Mobile IPv4 [1] section no need to deny the registration as stated in Mobile IPv4 [1] section
3.8.3.2. 3.8.3.2.
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When the destination IP address is a unicast address and the Home When the destination IP address is a unicast address and the Home
Agent field is ALL-ZERO-ONE-ADDR, the HA accepts/denies registration Agent field is ALL-ZERO-ONE-ADDR, the HA accepts/denies registration
and sets the HA field to its own IP address in the reply (i.e. the and sets the HA field to its own IP address in the reply (i.e. the
registration is not rejected with error code 136). registration is not rejected with error code 136).
The HA can reject the request with the error code REDIRECT-HA-REQ and The HA can reject the request with the error code REDIRECT-HA-REQ and
suggest an alternate HA. This redirection can be used for load suggest an alternate HA. This redirection can be used for load
balancing, geographical proximity based on care-of-address or other balancing, geographical proximity based on care-of-address or other
reasons. The HA puts its own address in HA field of the Registration reasons. The HA puts its own address in HA field of the Registration
Reply message and puts the address of the redirected HA in the Reply message and puts the address of the redirected HA in the
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MN performs challenge/response [5] with the FA. The FA retrieves the MN performs challenge/response [5] with the FA. The FA retrieves the
Requested HA from the AAA server and forwards the Registration Requested HA from the AAA server and forwards the Registration
Request directly to this HA. The Assigned HA sends a Registration Request directly to this HA. The Assigned HA sends a Registration
Reply to the FA, which relays it to the MN. MN uses the Assigned HA Reply to the FA, which relays it to the MN. MN uses the Assigned HA
for the remainder of the Mobile IP session. for the remainder of the Mobile IP session.
DNS: DNS:
In this case the hostname of the HA is configured on the MN or In this case the hostname of the HA is configured on the MN or
obtained by some other means; e.g., using a service location obtained by some other means; e.g., using a service location
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protocol. MN performs DNS lookup on the HA hostname. The DNS protocol. MN performs DNS lookup on the HA hostname. The DNS
infrastructure provides a resource record with information to infrastructure provides a resource record with information to
identify the optimal HA to the MN. The MN sends a Registration identify the optimal HA to the MN. The MN sends a Registration
Request directly to the HA and receives the Assigned HA to be used Request directly to the HA and receives the Assigned HA to be used
for remainder of the Mobile IP session. for remainder of the Mobile IP session.
Static configuration: Static configuration:
The HA address is statically configured on the MN. The MN sends the The HA address is statically configured on the MN. The MN sends the
Registration Request to the configured address. The Requested HA may Registration Request to the configured address. The Requested HA may
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the range 128-255). the range 128-255).
IANA should record the values as defined in Section 7 and 3.4. IANA should record the values as defined in Section 7 and 3.4.
9. Security Considerations 9. Security Considerations
This specification assumes that a security configuration has been This specification assumes that a security configuration has been
preconfigured between the MN and the HA or is configured along with preconfigured between the MN and the HA or is configured along with
the initial RRQ/RRP as per [7]. the initial RRQ/RRP as per [7].
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This specification does not change the security model established in This specification does not change the security model established in
Mobile IPv4 [1]. Mobile Nodes are often connected to the network via Mobile IPv4 [1]. Mobile Nodes are often connected to the network via
wireless links, which may be more prone to passive eavesdropping or wireless links, which may be more prone to passive eavesdropping or
replay attacks. Such an attack might lead to bogus registrations or replay attacks. Such an attack might lead to bogus registrations or
redirection of traffic or denial of service. redirection of traffic or denial of service.
As per the messaging in this draft, the Assigned Home Agent will As per the messaging in this draft, the Assigned Home Agent will
process the incoming Registration Request as per Mobile IPv4 [1]. process the incoming Registration Request as per Mobile IPv4 [1].
Hence the Assigned Home Agent will have same security concerns as Hence the Assigned Home Agent will have same security concerns as
that of the Home Agent in Mobile IPv4 [1]. They are addressed in that of the Home Agent in Mobile IPv4 [1]. They are addressed in
Section 5 "Security Considerations" of Mobile IPv4 [1]. Section 5 "Security Considerations" of Mobile IPv4 [1].
The Registration Request and Registration Reply messages are The Registration Request and Registration Reply messages are
protected by a valid authenticator as specified in Mobile IPv4 [1]. protected by a valid authenticator as specified in Mobile IPv4 [1].
Configuring security associations is a deployment specific issue and Configuring security associations is a deployment specific issue and
is covered by other Mobile IP specifications. There can be many ways is covered by other Mobile IP specifications. There can be many ways
of configuring security associations, but this specification does not of configuring security associations, but this specification does not
mandate any specific way. require any specific way.
An example is where the security association between an MN and an An example is where the security association between an MN and an
individual HA (Requested or Assigned) is dynamically derived during individual HA (Requested or Assigned) is dynamically derived during
the registration process based on a shared secret between MN and AAA the registration process based on a shared secret between MN and AAA
infrastructure, as defined in [7]. The Registration Request is infrastructure, as defined in [7]. The Registration Request is
protected with MN-AAA authentication extension and Registration Reply protected with MN-AAA authentication extension and Registration Reply
is protected with MN-HA Authentication Extension. Because the is protected with MN-HA Authentication Extension. Because the
security association is shared between MN and AAA, any dynamically security association is shared between MN and AAA, any dynamically
assigned HA in the local domain can proxy authenticate the MN using assigned HA in the local domain can proxy authenticate the MN using
AAA as per [7]. AAA as per [7].
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Legacy Home Agent: Legacy Home Agent:
Legacy home agents may reject the Registration Request with error Legacy home agents may reject the Registration Request with error
code 136 because the Home Agent field is not a unicast address. code 136 because the Home Agent field is not a unicast address.
However, some legacy HA implementations may coincidentally process However, some legacy HA implementations may coincidentally process
the Registration Request in accordance with this draft, when the HA the Registration Request in accordance with this draft, when the HA
field in Registration Request is set to ALL-ZERO-ONE-ADDR. field in Registration Request is set to ALL-ZERO-ONE-ADDR.
Legacy Foreign Agent: Legacy Foreign Agent:
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Legacy foreign agents may forward a Registration Request with home Legacy foreign agents may forward a Registration Request with home
agent field set to ALL-ZERO-ONE-ADDR by setting the destination IP agent field set to ALL-ZERO-ONE-ADDR by setting the destination IP
address to ALL-ZERO-ONE-ADDR. This will result packet being dropped address to ALL-ZERO-ONE-ADDR. This will result packet being dropped
or incidentally handled by a next hop HA, adjacent to the FA. or incidentally handled by a next hop HA, adjacent to the FA. The MN
may not be aware of the dropped Registration Request and may probably
retry registration, thereby increasing the delay in registration.
To reduce the delay in registration, the MN should take following
steps:
1. The MN should send the Registration Request as specified in this
specification. In other words, the MN should set the home agent
field in the Registration Request to ALL-ZERO-ONE-ADDR and also add
the Requested HA Extension.
2. If the MN does not receive a Registration Reply within some time
and/or after sending a few Registration Requests, it can assume
that the Registration Request(s) has been dropped, either by a
legacy FA or an incorrect HA. The MN then should fall back to a
recovery mechanism. The MN should quickly send a new Registration
Request as mentioned in section 4.1 step 2. This step will ensure
that a legacy FA will forward the Registration Request to the Home
Agent thereby making dynamic HA assignment possible.
Legacy Mobile Node: Legacy Mobile Node:
A MN that does not set HA field to ALL-ZERO-ONE-ADDR will continue to A MN that sends a registration request to an FA which can do dynamic
achieve its registrations through statically configured HA. In HA assignment, but does not set the HA field to ALL-ZERO-ONE-ADDR
collocated mode, the endpoint of the MN's tunnel is the Assigned HA. will continue to be registered with its statically configured HA,
exactly according to RFC 3344.
11. Change Log from previous versions 11. Change Log from previous versions
Note: This section should be removed before publication. Note: This section should be removed before publication.
Changes from revision 3 to 4:
1. Text added to clarify the cases when MN is configured with HA
address and not configured with HA address and requests
dynamic HA assignment.
2. Clarification on legacy FA section as suggested by Thomas
Narten.
3. More editorial changes suggested by the chairs.
Changes from revision 2 to 3: Changes from revision 2 to 3:
1. More editorial changes suggested by the chair's reviews. 1. More editorial changes suggested by the chairs.
Changes from revision 1 to 2: Changes from revision 1 to 2:
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1. Editorial changes suggested by the WG, the chair's reviews and 1. Editorial changes suggested by the WG, the chair's reviews and
idnits. idnits.
Changes from revision 0 to 1: Changes from revision 0 to 1:
1. Added subtype field in Redirected HA Address Extension. 1. Added subtype field in Redirected HA Address Extension.
2. Aligned the HA address at 4-byte world boundary. 2. Aligned the HA address at 4-byte world boundary.
3. The case of handling unicast HA field is removed in section 3. The case of handling unicast HA field is removed in section
5.3.1. 5.3.1.
skipping to change at page 20, line 49 skipping to change at line 1046
Authors' Addresses Authors' Addresses
Milind Kulkarni Milind Kulkarni
Cisco Systems Inc. Cisco Systems Inc.
170 W. Tasman Drive, 170 W. Tasman Drive,
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: mkulkarn@cisco.com Email: mkulkarn@cisco.com
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Phone:+1 408-527-8382 Phone:+1 408-527-8382
Alpesh Patel Alpesh Patel
Cisco Systems Inc. Cisco Systems Inc.
170 W. Tasman Drive, 170 W. Tasman Drive,
San Jose, CA 95134 San Jose, CA 95134
USA USA
Email: alpesh@cisco.com Email: alpesh@cisco.com
Phone:+1 408-853-9580 Phone:+1 408-853-9580
skipping to change at page 21, line 50 skipping to change at line 1097
any copyrights, patents or patent applications, or other any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be required to proprietary rights that may cover technology that may be required to
implement this standard. Please address the information to the IETF implement this standard. Please address the information to the IETF
at ietf-ipr@ietf.org. at ietf-ipr@ietf.org.
Disclaimer of Validity Disclaimer of Validity
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
Kulkarni, Patel, Leung Expires November 28, 2005 [Page 22]
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2003). This document is subject Copyright (C) The Internet Society (2003). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgement Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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 End of changes. 

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