draft-ietf-mip4-dynamic-assignment-07.txt   rfc4433.txt 
Mobile IP Working Group Milind Kulkarni Network Working Group M. Kulkarni
INTERNET-DRAFT Alpesh Patel Request for Comments: 4433 A. Patel
Category: Standards Track Kent Leung Category: Standards Track K. Leung
Date : 12 December 2005 Cisco Systems Inc. Cisco Systems Inc.
March 2006
Mobile IPv4 Dynamic Home Agent Assignment
draft-ietf-mip4-dynamic-assignment-07.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at Mobile IPv4 Dynamic Home Agent (HA) Assignment
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at Status of This Memo
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on June 12, 2006. This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
Abstract Abstract
Mobile IPv4 [1] uses the Home Agent (HA) to anchor sessions of a Mobile IPv4 (RFC 3344) uses the home agent (HA) to anchor sessions of
roaming Mobile Node (MN). This draft proposes a messaging mechanism a roaming mobile node (MN). This document proposes a messaging
for dynamic home agent assignment and HA redirection. The goal is to mechanism for dynamic home agent assignment and HA redirection. The
provide a mechanism to assign an optimal HA for a Mobile IP session goal is to provide a mechanism to assign an optimal HA for a Mobile
while allowing any suitable method for HA selection. IP session while allowing any suitable method for HA selection.
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 ...............................................5
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.........................6 3.3. NAI Usage and Dynamic HA Assignment ........................6
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 ..............................7
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...............................10 4.2. Messaging for HA Redirection ..............................10
4.2.1 Example with Message Flow Diagram........................11 4.2.1. Example with Message Flow Diagram ..................12
5. Mobility Agent Considerations..............................12 5. Mobility Agent Considerations ..................................14
5.1 Mobile Node Considerations.................................12 5.1. Mobile Node Considerations ................................14
5.1.1 MN using FA CoA..........................................13 5.1.1. MN Using FA CoA ....................................14
5.1.2 MN using Co-located CoA..................................14 5.1.2. MN Using Co-Located CoA ............................15
5.1.3 Refreshing Assigned HA Address on Mobile Node............14 5.1.3. Refreshing Assigned HA Address on Mobile Node ......16
5.2 Foreign Agent Considerations...............................15 5.2. Foreign Agent Considerations ..............................16
5.3 Home Agent Considerations..................................15 5.3. Home Agent Considerations .................................17
5.3.1 Assigned Home Agent Considerations.......................16 5.3.1. Assigned Home Agent Considerations .................17
6. Requested Home Agent Selection.............................17 6. Requested Home Agent Selection .................................19
7. Error Values...............................................18 7. Error Values ...................................................20
8. IANA Considerations........................................18 8. IANA Considerations ............................................20
9. Security Considerations....................................19 9. Security Considerations ........................................20
10. Backward Compatibility Considerations.....................20 10. Backward-Compatibility Considerations .........................21
11. Change Log from previous versions.........................21 11. Acknowledgements ..............................................23
12. Acknowledgements..........................................22 12. Normative References ..........................................23
13. Normative References......................................22
Authors' Addresses.............................................23
Intellectual Property Statement................................23
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.
The MN requests a dynamically assigned HA by setting the HA field in The MN requests a dynamically assigned HA by setting the HA field in
the initial Registration Request to ALL-ZERO-ONE-ADDR (defined in the initial Registration Request to ALL-ZERO-ONE-ADDR (defined in
section 2). If the request is accepted, the HA sends a successful Section 2). If the request is accepted, the HA sends a successful
Registration Reply containing the HA's own address. The requested HA Registration Reply containing the HA's own address. The requested HA
can suggest an alternate HA and if so, the Registration Reply is can suggest an alternate HA and if so, the Registration Reply is
rejected with a new error code REDIRECT-HA-REQ and the alternate HA rejected with a new error code REDIRECT-HA-REQ and the alternate HA
address is specified in a new extension (Redirected HA Extension). address is specified in a new extension (Redirected HA Extension).
This document also defines a new Requested HA Extension for use in This document also defines a new Requested HA Extension for use in
Registration Requests when the HA field is set to ALL-ZERO-ONE- Registration Requests when the HA field is set to ALL-ZERO-ONE-ADDR.
ADDRESS. The Requested HA address is a hint to the network about the The Requested HA address is a hint to the network about the MN's
MN's preferred HA. preferred HA.
The messaging mechanism is defined in this document so that the The messaging mechanism is defined in this document so that the MN
MN can request and receive a dynamic HA address in Mobile IP can request and receive a dynamic HA address in Mobile IP messages.
messages. However, the mechanism by which the network selects However, the mechanism by which the network selects an HA for
an HA for assignment to the MN is outside the scope of this assignment to the MN is outside the scope of this document. For
document. For example, the selection may be made by any example, the selection may be made by any network node that receives
network node that receives the registration request (or the Registration Request (or information about the Registration
information about the registration request), such as a Foreign Request), such as a Foreign Agent, AAA server, or home agent. The
Agent, AAA server, or Home Agent. The node that selects the node that selects the HA may select one based on a number of
HA may select one based on a number of criteria, including but criteria, including but not limited to HA load-balancing,
not limited to HA load-balancing, geographical proximity, geographical proximity, administrative policy, etc.
administrative policy etc.
2. Requirements Terminology 2. Requirements Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [6]. document are to be interpreted as described in RFC 2119 [6].
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.
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
and returns a successful Registration Reply. and returns a successful Registration Reply.
Redirected HA: If the registration is rejected with error code Redirected HA: If the registration is rejected with error code
REDIRECT-HA-REQ, the HA being referred to is REDIRECT-HA-REQ, the HA being referred to is
specified in a new extension (Redirected HA specified in a new extension (Redirected HA
Extension). Extension).
AAA server: Authentication, Authorization and Accounting AAA server: Authentication, Authorization, and Accounting
Server. Server.
DNS: Domain Name System. DNS: Domain Name System.
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: Co-located 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.
RRQ: Registration Request. RRQ: Registration Request.
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 an 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:
- 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
may be long. In such a case the MN will be anchored to its distant registrations may be long. In such a case, the MN will be anchored
home agent, resulting in tunneled traffic traveling a long distance to its distant home agent, resulting in tunneled traffic traveling
between home agent and the mobile node. When a Mobile IP session a long distance between home agent and the mobile node. When a
initiates, if the mobile node can be assigned a home agent that is Mobile IP session initiates, if the mobile node can be assigned a
close to the mobile node it can drastically reduce the latency home agent that is close to the mobile node it can drastically
between the home agent and mobile node. reduce the latency 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
provision MNs with multiple HA addresses. provision MNs with multiple HA addresses.
- It is desirable to achieve some form of load balancing between - It is desirable to achieve some form of load balancing between
multiple HAs in the network. Dynamic HA assignment and/or HA multiple HAs in the network. Dynamic HA assignment and/or HA
redirection lets the network select the optimal HA from among a set redirection lets the network select the optimal HA from among a set
of HAs and thus achieve load balancing among a group of HAs. of HAs and thus achieve load balancing among a group of HAs.
- Local administrative policies. - Local administrative policies.
3.1 Scope 3.1. Scope
This specification does not address the problem of distributing a This specification does not address the problem of distributing a
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 document 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 that 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 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. 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
The Mobile IPv4 NAI Extension for IPv4 [2] introduced the The Mobile IPv4 NAI Extension for IPv4 [2] introduced the concept of
concept of identifying a MN by the NAI and enabling dynamic identifying an MN by the NAI and enabling dynamic home address
home address assignment. This document requires that while assignment. This document requires that while using dynamic HA
using dynamic HA assignment, MN MUST use the NAI and obtain a home assignment, MN MUST use the NAI and obtain a home address. MN can
address. MN can still suggest a static home address in the still suggest a static home address in the Registration Request, but
Registration Request, but must take the address in the Registration must take the address in the Registration Reply as the home address
Reply as the home address for the session. This is compatible with for the session. This is compatible with the procedures documented
the procedures documented in the NAI specification [2]. 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
Request and Reply messages. It is a skippable extension. Request and Reply messages. It is a skippable extension.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Sub-Type | Length | | Type | Subtype | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| HA-Address | | HA-Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: The Dynamic HA address Extension Figure 1: The Dynamic HA Address Extension
Type DYNAMIC-HA-ADDRESS (skippable) (to be assigned by Type DYNAMIC-HA-ADDRESS (skippable) 139 is the type,
IANA) is the type, which specifies the dynamic HA which specifies the dynamic HA address.
address.
Sub-Type Defines the use of this extension as: Subtype Defines the use of this extension as:
sub-type 1 = Requested HA Extension subtype 1 = Requested HA Extension
2 = Redirected HA Extension 2 = Redirected HA Extension
Length Indicates the length of the extension not Length Indicates the length of the extension not
including the type, sub-type and length fields. including the type, subtype, and length fields.
Length is always 4 bytes. Length is always 4 bytes.
HA-Address Address of the Home Agent. HA-Address Address of the home agent.
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.
In absence of an FA, the Registration Request is forwarded to this In absence of an FA, the Registration Request is forwarded to this
HA. In presence of an FA, the FA MUST forward Registration Request HA. In presence of an FA, the FA MUST forward the Registration
to the HA address in this extension. Request 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
Registration Reply is sent with a new error code REDIRECT-HA-REQ and Registration Reply is sent with a new error code REDIRECT-HA-REQ and
the alternate HA address is specified in this extension. the alternate HA address is specified in this extension.
The Redirected HA Extension MUST be included in Registration Reply The Redirected HA Extension MUST be included in Registration Reply
when the reply code is REDIRECT-HA-REQ. when the reply code is REDIRECT-HA-REQ.
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:
(a) Dynamic HA assignment (described in section 4.1) and
(b) HA redirection (described in section 4.2).
4.1 Messaging for dynamic HA assignment (a) Dynamic HA assignment (described in Section 4.1) and
(b) HA redirection (described in Section 4.2).
4.1. Messaging for Dynamic HA Assignment
The following sequence of events occurs when the MN requests dynamic The following sequence of events occurs when the MN requests dynamic
Home Agent assignment: home agent 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. 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. If the HA does not support the the Registration Request. If the HA does not support the
Requested HA Extension, see step 2 below. Requested HA Extension, see step 2 below.
2. This step is applicable, in lieu of step 1, for a MN that is 2. This step is applicable, in lieu of step 1, for an MN that is
aware of the HA address and desires dynamic HA assignment. Also, aware of the HA address and desires dynamic HA assignment. Also,
the MN follows this (when aware of a HA address) when it 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 discovers a legacy FA in the path or if the known HA does not
support the Requested HA Extension (see section 10). support the Requested HA Extension (see Section 10).
The MN sets the Home Agent address field in the Registration The MN sets the Home Agent address field in the Registration
Request to the HA address (instead of setting it to ALL-ZERO-ONE- Request to the HA address (instead of setting it to ALL-ZERO-
ADDR). The MN also adds the same HA address in the Requested HA ONE-ADDR). The MN also adds the same HA address in the Requested
Extension in the Registration Request. HA Extension in the Registration Request.
3. The MN (if using co-located CoA and registering directly with the 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.
Per section 10, in case of a legacy FA, legacy FA forwards the
Per Section 10, in case of a legacy FA, legacy FA forwards the
Registration Request to the address in the HA field of 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 request (thus, MN uses step 2 above in case of legacy FA instead
of step 1). of step 1).
4. The "Requested HA" is the home agent that processes the 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 a successful Registration Request. It also sends a
Registration Reply to the MN. Registration Reply to the MN.
5. 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 the same as
"Requested HA"). the "Requested HA".)
6. 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
located Care of Address (FA CoA) and FA understands the Requested HA FA-located Care-of Address (FA CoA) and FA understands the Requested
Extension per this specification. HA Extension per this specification.
Other scenarios such as when the mobile node uses a co-located care Other scenarios such as when the mobile node uses a co-located care
of address and presence of a legacy HA or FA are not described below, of address and presence of a legacy HA or FA are not described below,
but the behavior is similar. 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 |
|----------------------------->| |----------------------------->|
| | | | | |
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
example, it sends the Registration Request to the FA. The this 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 |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
If the MN is aware of a desired HA address, it can add that address If the MN is aware of a desired HA address, it can add that
in the Requested HA Extension in Registration Request as a hint. address in the Requested HA Extension in Registration Request as
That extension is not shown above. a hint. That extension is not shown above.
2. The FA sends the Registration Request to the Requested HA. If 2. The FA sends the Registration Request to the Requested HA. If
Requested HA Extension is present, Requested HA is the HA address in the Requested HA Extension is present, Requested HA is the HA
this extension. If the Requested HA Extension is not present, the FA address in this extension. If the Requested HA Extension is not
determines the Requested HA through means outside the scope of this present, the FA determines the Requested HA through means outside
specification. The Registration Request is formatted as follows: the scope of this specification. The Registration Request is
formatted as follows:
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| 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 |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
(If MN includes the Requested HA Extension, the FA copies that (If MN includes the Requested HA Extension, the FA copies that
extension. The FA then forwards the Registration Request, along with extension. The FA then forwards the Registration Request, along
the Requested HA Extension, to the HA address specified in Requested with the Requested HA Extension, to the HA address specified in
HA Extension.) Requested HA Extension.)
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 document. The HA Mobile IPv4 [1] and the messaging defined in this document. The
creates mobility binding for successful request and becomes the HA creates mobility binding for successful request and becomes
Assigned HA. The HA then sends Registration Reply to the FA, which the Assigned HA. The HA then sends a Registration Reply to the
is formatted as follows: FA, which is formatted as follows:
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Src IP=| Dest IP = | MN HoA | HA Address = | CoA = | | Src IP=| Dest IP = | MN HoA | HA Address = | CoA = |
|Assigned| Src IP of | | Assigned HA |FA CoA/| |Assigned| Src IP of | | Assigned HA |FA CoA/|
| 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/|
+-----------------------------------------------------------+ +-----------------------------------------------------------+
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
session. The MN sends subsequent Re-Registration or De-Registration the session. The MN sends subsequent Re-Registration or
Requests for the remainder session directly to the Assigned HA. The De-Registration Requests for the remainder session directly to
Home Agent address field in this Registration Request is set to the Assigned HA. The Home Agent address field in this
ALL-ZERO-ONE-ADDR. Note that the Assigned HA is the same as the Registration Request is set to ALL-ZERO-ONE-ADDR. Note that the
Requested HA. 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
does not accept the Registration Request and redirects the mobile HA does not accept the Registration Request and redirects the
node to another HA (aka Redirected HA) instead. This behavior is not mobile node to another HA (aka Redirected HA) instead. This
exhibited by a legacy HA and so is not referred in the description behavior is not exhibited by a legacy HA and so is not referred
below. In presence of a legacy FA, please refer to section 4.1 for in the description below. In presence of a legacy FA, please
the specific field in the Registration Request. 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 co-located 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
an HA address, it can add that address in the Requested HA of an HA address, it can add that address in the Requested HA
Extension in Registration Request. Extension in the 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
code REDIRECT-HA-REQ and suggest an alternate HA. Reply 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
outside the scope of this specification. If the HA rejects the outside the scope of this specification. If the HA rejects the
Request, the HA field in the Reply is set to this HAs address. Request, the HA field in the Reply is set to this HA's address.
The IP address of the HA that is the target of the redirection is The IP address of the HA that is the target of the redirection is
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-
REQ. HA sends the Reply to the FA/MN. HA-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, the MN obtains the
address from Redirected HA Extension. The MN then sends a HA address from Redirected HA Extension. The MN then sends a
Registration Request to Redirected HA. The MN may choose to add Registration Request to Redirected HA. The MN may choose to add
Requested HA extension in this new Registration Request. If a Requested HA Extension in this new Registration Request. If a
registration loop occurs (the case when the Redirected HA is an HA registration loop occurs (the case when the Redirected HA is an
that had already directed the MN to register elsewhere) then the HA that had already directed the MN to register elsewhere), then
MN stops sending any further Registration Request and provides an the MN stops sending any further Registration Request and
indication that the loop event was detected. The number of provides an indication that the loop event was detected. The
consecutive Redirected HAs remembered by MN for loop detection is number of consecutive Redirected HAs remembered by the MN for
an implementation parameter. loop detection is an implementation parameter.
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, where the FA is not a legacy FA. Care-of Address, where the FA is not a legacy FA.
MN FA Requested HA Redirected HA MN FA Requested HA Redirected HA
| 1 | | | | 1 | | |
|------------>| 2 | | |------------>| 2 | |
| |--------------->| | | |--------------->| |
| | | | | | | |
| | | | | | | |
| | 3 | | | | 3 | |
| 4 |<---------------| | | 4 |<---------------| |
|<------------| | | |<------------| | |
| | | | | | | |
| | 5 | | | | 5 | |
|--------------------------------------------->| |--------------------------------------------->|
| | | | | | | |
Figure 3: Example message flow for HA redirection Figure 3: Example Message Flow for HA Redirection
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
example, it sends the Registration Request to the FA. The this 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 |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
If the MN is aware of an HA address, it can add that address in the If the MN is aware of an HA address, it can add that address in
Requested HA Extension in Registration Request as a hint. That the Requested HA Extension in the Registration Request as a hint.
extension is not shown above. That extension is not shown above.
2. The FA sends the Registration Request to the Requested HA. If 2. The FA sends the Registration Request to the Requested HA. If
Requested HA Extension is present, Requested HA is the HA address in Requested HA Extension is present, Requested HA is the HA address
this extension. If the Requested HA Extension is not present, the FA in this extension. If the Requested HA Extension is not present,
determines the Requested HA through means outside the scope of this the FA determines the Requested HA through means outside the
specification. The Registration Request is formatted as follows: scope of this specification. The Registration Request is
formatted as follows:
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| 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.
the registration is successful, but local configuration/ If the registration is successful, but local
administrative policy etc. directs HA to refer the MN to another HA, configuration/administrative policy, etc., directs the HA to
the HA rejects the Request with error code REDIRECT-HA-REQ. The HA refer the MN to another HA, the HA rejects the request with error
fills in the address of the Redirected HA in the Redirected HA code REDIRECT-HA-REQ. The HA fills in the address of the
Extension. The HA then sends Registration Reply reject to the FA, Redirected HA in the Redirected HA Extension. The HA then sends
which is formatted as follows: Registration Reply reject to the FA, 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 ... |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
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 | | 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. The MN may choose to add Requested HA Registration Request. The MN may choose to add Requested HA
extension in this new Registration Request. 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.
Since MN uses the NAI extension, the Home Address field is set to Since MN uses the NAI extension, the Home Address field is set to
0.0.0.0. 0.0.0.0.
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 an MN and an individual HA may also be
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.
As mentioned in the Security Considerations (Section 9), there is a As mentioned in the Security Considerations (Section 9), there is a
possibility of more than one HA create a mobility binding entry for a possibility of more than one HA creating a mobility binding entry for
given MN, if a rogue node in the middle captures the Registration a given MN, if a rogue node in the middle captures the Registration
Request and forwards it to other Home Agents. MN can mitigate such Request and forwards it to other home agents. The MN can mitigate
condition by using a short lifetime (e.g. 5 seconds) in the such condition by using a short lifetime (e.g., 5 seconds) in the
Registration Request with Home Agent field set to ALL-ZERO-ONE-ADDR. Registration Request with the Home Agent field set to ALL-ZERO-ONE-
ADDR.
The following sections describe MN behavior in FA CoA mode and co- The following sections describe MN behavior in FA CoA mode and co-
located 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 document.
The Registration Request MUST be appropriately authenticated for the The Registration Request MUST be appropriately authenticated for the
HA to validate the Request. HA to validate the Request.
If a successful Registration Reply is received, the MN obtains the If a successful Registration Reply is received, the MN obtains the
Assigned HA from the HA field of Reply. The Assigned HA address will Assigned HA from the HA field of Reply. The Assigned HA address will
be the same as the Requested HA Extension, if it was included in the be the same as the Requested HA Extension, if it was included in the
Registration Request by the MN. Registration Request by the MN.
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.
5.1.2 MN using Co-located CoA 5.1.2. MN Using Co-Located CoA
An MN in co-located 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
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 co-located CoA but registering via a legacy FA, the HA When using co-located CoA but registering via a legacy FA, the HA
field in Reqistration Request may be set to Requested HA. field in the Registration Request may be set to Requested HA.
If the Registration Request contains the Requested HA Extension, the If the Registration Request contains the Requested HA Extension, the
HA address in that extension MUST match the destination IP of the HA address in that extension MUST match the destination IP of the
Request. 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.
5.2 Foreign Agent Considerations 5.2. Foreign Agent Considerations
When the mobile node is using a FA CoA it always registers via the When the mobile node is using an FA CoA, it always registers via the
FA. When the MN is using a co-located CoA it may register through a FA. When the MN is using a co-located CoA, it may register through
FA or it may register directly with an HA, unless the R bit is set in an FA or it may register directly with an HA, unless the R bit is set
the FA's agent advertisement, in which case it always registers in the FA's agent advertisement, in which case it always registers
through the 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
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 the MN, it MUST reject request with error
NONZERO-HA-REQD. code 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 the Registration Request to the address in this extension.
the HA address in this extension is not a routable unicast address, If the HA address in this extension is not a routable unicast
the FA MUST reject request with error code NONZERO-HA-REQD. address, the FA MUST reject the request with error code NONZERO-HA-
REQD.
If the Registration Request contains the Requested HA Extension, the If the Registration Request contains the Requested HA Extension, the
FA uses that address as the destination for the relayed Registration FA uses that address as the destination for the relayed Registration
Request. Request.
Backward compatibility issues related to the mobility agents are Backward-compatibility issues related to the mobility agents are
addressed in section 10. addressed in Section 10.
5.3 Home Agent Considerations 5.3. Home Agent Considerations
A Home Agent can process an incoming Registration Request in one of A home agent can process an incoming Registration Request in one of
the following two ways: the following two ways:
1. The MN or FA sends the Registration Request to the Requested HA. 1. The MN or FA sends the Registration Request to the Requested HA.
The term Requested HA has meaning in the context of a Registration The term Requested HA has meaning in the context of a
Request message. When the Requested HA successfully processes the Registration Request message. When the Requested HA successfully
Registration Request and creates a binding and sends a Reply with its processes the Registration Request and creates a binding and
address, it becomes the Assigned HA. The term Assigned HA is sends a Reply with its address, it becomes the Assigned HA. The
meaningful in the context of a Registration Reply message. term Assigned HA is meaningful in the context of a Registration
Reply message.
2. A Home Agent receiving a Registration Request with HA field set 2. A home agent receiving a Registration Request with HA field set
to ALL-ZERO-ONE-ADDR MAY reject the request even if successfully to ALL-ZERO-ONE-ADDR MAY reject the request even if successfully
authenticated and suggest an alternate HA address in Reply. In such authenticated and suggest an alternate HA address in Reply. In
a case, the HA puts its own address in HA field of Reply and sets the such a case, the HA puts its own address in HA field of Reply and
Reply code to REDIRECT-HA-REQ and adds the Redirected HA Extension. sets the Reply code to REDIRECT-HA-REQ and adds the Redirected HA
Extension.
If the Registration Request contains the Requested HA Extension, the If the Registration Request contains the Requested HA Extension, the
HA address in that extension must match the destination IP of the HA address in that extension must match the destination IP of the
Request. If it does not match, the Requested HA MUST reject the Request. If it does not match, the Requested HA MUST reject the
Registration Request with error code 136. Registration Request with error code 136.
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 the
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.
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
equal to the for reference only. equal to the for reference only.
HA receiving HA denies the registration with HA receiving HA denies the registration with
the RRQ) error code 136 and sets HA field to the RRQ) error code 136 and sets HA field to
its own IP address in the reply as its own IP address in the reply as
per section 3.8.3.2 in [1]. per Section 3.8.3.2 in [1].
ALL-ZERO- New Behavior: Accept the RRQ as per ALL-ZERO- New Behavior: Accept the RRQ as per
ONE-ADDR this specification. Authenticate ONE-ADDR this specification. Authenticate
the RRQ and create mobility binding the RRQ and create mobility binding
if the HA is acting as Assigned HA. if the HA is acting as Assigned HA.
Set HA field to its own IP address Set HA field to its own IP address
in the Registration Reply. in the Registration Reply.
OR OR
New Behavior: If authentication is New Behavior: If authentication is
successful, reject RRQ with a new successful, reject RRQ with a new
error code REDIRECT-HA-REQ. HA error code REDIRECT-HA-REQ. HA
puts its address in HA address puts its address in HA address
field of Reject. HA suggests an field of Reject. HA suggests an
alternate HA to use in the new alternate HA to use in the new
Redirected HA Extension. Redirected HA Extension.
Table 1: Registration Request handling at Assigned HA Table 1: Registration Request Handling at Assigned HA
As per the messaging proposed here, the mobile node (or the foreign As per the messaging proposed here, the mobile node (or the foreign
agent) sends the Registration Request to the Requested HA address, agent) sends the Registration Request to the Requested HA address,
which is a unicast address. Therefore, this document does not which is a unicast address. Therefore, this document does not
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
problem associated with subnet-directed broadcast destination IP associated with subnet-directed broadcast destination IP address that
address that may result in multiple HAs responding. Thus, there is may result in multiple HAs responding. Thus, there is no need to
no need to deny the registration as stated in Mobile IPv4 [1] section deny the registration as stated in Mobile IPv4 [1] Section 3.8.3.2.
3.8.3.2.
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 the HA field of the
Reply message and puts the address of the redirected HA in the Registration Reply message and puts the address of the redirected HA
Redirected HA Extension. If the HA accepts the Request, it sets the in the Redirected HA Extension. If the HA accepts the Request, it
HA field in the Registration Reply to its own address. sets the HA field in the Registration Reply to its own address.
The Requested HA always performs standard validity checks on the The Requested HA always performs standard validity checks on the
Registration Request. If there is any error, the Registration Registration Request. If there is any error, the Registration
Request is rejected with error codes specified in Mobile IPv4 [1]. Request is rejected with error codes specified in Mobile IPv4 [1].
6. Requested Home Agent Selection 6. Requested Home Agent Selection
When dynamic HA assignment is requested, the MN (or FA in the case of When dynamic HA assignment is requested, the MN (or FA in the case of
registration via FA) sends the Registration Request to the Requested registration via FA) sends the Registration Request to the Requested
HA. This address MUST be a unicast IP address. If the MN has HA. This address MUST be a unicast IP address. If the MN has
included a Requested HA Extension in Registration Request, the HA included a Requested HA Extension in the Registration Request, the HA
address in this extension is the Requested HA. address in this extension is the Requested HA.
Some example methods by which the MN or the FA may select the Some examples of methods by which the MN or the FA may select the
Requested HA are briefly described below: Requested HA are briefly described below:
DHCP: DHCP:
MN performs DHCP to obtain an IP address on the visited network. The The MN performs DHCP to obtain an IP address on the visited
Requested HA is learned from the DHCP Mobile IP Home Agent Option 68 network. The Requested HA is learned from the DHCP Mobile IP Home
[4]. MN sends Registration Request directly to this HA and receives Agent Option 68 [4]. The MN sends the Registration Request
the Assigned HA to be used for the remainder of the Mobile IP directly to this HA and receives the Assigned HA to be used for
session. the remainder of the Mobile IP session.
AAA: AAA:
MN performs challenge/response [5] with the FA. The FA retrieves the MN performs challenge/response [5] with the FA. The FA retrieves
Requested HA from the AAA server and forwards the Registration the 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
for the remainder of the Mobile IP session. HA 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
protocol. MN performs DNS lookup on the HA hostname. The DNS protocol. The 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 the 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
Registration Request to the configured address. The Requested HA may the Registration Request to the configured address. The Requested
then redirect the MN to a Redirected HA. HA may then redirect the MN to a Redirected HA.
7. Error Values 7. Error Values
Each entry in the following table contains the name and value for the Each entry in the following table contains the name and value for the
error code to be returned in a Registration Reply. It also includes error code to be returned in a Registration Reply. It also includes
the section in which the error code is first mentioned in this the section in which the error code is first mentioned in this
document. document.
Error Name Value Section Description Error Name Value Section Description
--------------- ----- ------- ----------------------------- --------------- ----- ------- -----------------------------
NONZERO-HA-REQD XX 5.2 Non-zero HA address required NONZERO-HA-REQD 90 5.2 Non-zero HA address required
in Registration Request. in Registration Request.
REDIRECT-HA-REQ YY 5.3 Reregister with redirected HA. REDIRECT-HA-REQ 143 5.3 Re-register with redirected HA.
8. IANA Considerations 8. IANA Considerations
The code value NONZERO-HA-REQD is a Mobile IP response code [1] taken The code value NONZERO-HA-REQD is a Mobile IP response code [1] taken
from the range of values associated with rejection by the foreign from the range of values associated with rejection by the foreign
agent (i.e. value in the range 64-127). agent (i.e., value in the range 64-127).
The code value REDIRECT-HA-REQ is a Mobile IP response code [1] taken The code value REDIRECT-HA-REQ is a Mobile IP response code [1] taken
from the range of values associated with rejection by the home agent from the range of values associated with rejection by the home agent
(i.e. value in the range 128-192). (i.e., value in the range 128-192).
The Dynamic HA Extension is assigned from the range of values The Dynamic HA Extension is assigned from the range of values
associated with skippable extensions at the home agent (i.e. value in associated with skippable extensions at the home agent (i.e., value
the range 128-255). in the range 128-255).
IANA should record the values as defined in Section 7 and 3.4. IANA has recorded the values as defined in Sections 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 Registration Request/Registration Reply as per [7]. the initial Registration Request/Registration Reply as per [7].
There is a possibility of more than one HA create a mobility binding There is a possibility of more than one HA creating a mobility
entry for a given MN, if a man in the middle captures the binding entry for a given MN, if a man in the middle captures the
Registration Request with HA field set to ALL-ZERO-ONE-ADDR and Registration Request with the HA field set to ALL-ZERO-ONE-ADDR and
forwards it to other HAs. This scenario assumes that the rogue node forwards it to other HAs. This scenario assumes that the rogue node
can find out the addresses of the HAs which are able to authenticate can find out the addresses of the HAs that are able to authenticate
the Registration Request. It also assumes that the rogue node has the Registration Request. It also assumes that the rogue node has
the capability to store, duplicate, and send packets to the other HAs the capability to store, duplicate, and send packets to the other HAs
within the limited time of the replay window. Otherwise these HAs within the limited time of the replay window. Otherwise, these HAs
will reject the Registration Requests anyway. In addition, this type will reject the Registration Requests anyway. In addition, this type
of attack is only possible when the Requested HA Extension is not of attack is only possible when the Requested HA Extension is not
included in the registration message. The Mobile Node can minimize included in the registration message. The mobile node can minimize
the duration of this condition by using a short lifetime (e.g. 5 the duration of this condition by using a short lifetime (e.g., 5
seconds) in the Registration Request. seconds) in the Registration Request.
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 document, 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 the same security concerns as
that of the Home Agent in Mobile IPv4 [1]. They are addressed in those 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
require 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
is protected with MN-HA Authentication Extension. Because the Reply 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].
The Assigned Home Agent authenticates each Registration Request from The Assigned Home Agent authenticates each Registration Request from
the mobile node as specified in Mobile IPv4 [1] and/or RFC-3012. The the mobile node as specified in Mobile IPv4 [1] and/or RFC 3012. The
MN also authenticates the Registration Reply from the Assigned HA, MN also authenticates the Registration Reply from the Assigned HA;
thus the existing trust model in Mobile IPv4 [1] is maintained. thus, the existing trust model in Mobile IPv4 [1] is maintained.
10. Backward Compatibility Considerations 10. Backward-Compatibility Considerations
In this section, we examine concerns that may arise when using this In this section, we examine concerns that may arise when using this
specification in a mixed environment where some nodes implement the specification in a mixed environment where some nodes implement the
specification and others do not. In each of the examples below, we specification and others do not. In each of the examples below, we
consider the case where one node is a "Legacy" node which does not consider the case where one node is a "legacy" node, which does not
implement the specification in the context of other nodes which do. implement the specification in the context of other nodes that do.
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 document, when the
field in Registration Request is set to ALL-ZERO-ONE-ADDR. HA field in Registration Request is set to ALL-ZERO-ONE-ADDR.
Legacy Foreign Agent: Legacy Foreign Agent:
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 in the packet being
or incidentally handled by a next hop HA, adjacent to the FA. The MN dropped or incidentally handled by a next-hop HA, adjacent to the FA.
may not be aware of the dropped Registration Request and may probably The MN may not be aware of the dropped Registration Request and may
retry registration, thereby increasing the delay in registration. probably retry registration, thereby increasing the delay in
registration.
To reduce the delay in registration, the MN should take following To reduce the delay in registration, the MN should take the following
steps: steps:
1. The MN should send the Registration Request as specified in this 1. The MN should send the Registration Request as specified in this
specification. In other words, the MN should set the home agent specification. In other words, the MN should set the Home Agent
field in the Registration Request to ALL-ZERO-ONE-ADDR and also add field in the Registration Request to ALL-ZERO-ONE-ADDR and also
the Requested HA Extension. add the Requested HA Extension.
2. If the MN does not receive a Registration Reply within some time 2. If the MN does not receive a Registration Reply within some time
and/or after sending a few Registration Requests, it can assume and/or after sending a few Registration Requests, it can assume
that the Registration Request(s) has been dropped, either by a that the Registration Request(s) has been dropped, either by a
legacy FA or an incorrect HA. In addition, if the registration is legacy FA or an incorrect HA. In addition, if the registration
denied with error code 70 (poorly formed Request), the MN can is denied with error code 70 (poorly formed Request), the MN can
assume that the legacy FA cannot process this message. In either assume that the legacy FA cannot process this message. In either
case, the MN should fall back to a recovery mechanism. The MN case, the MN should fall back to a recovery mechanism. The MN
should quickly send a new Registration Request as mentioned in should quickly send a new Registration Request as mentioned in
section 4.1 step 2. This step will ensure that a legacy FA will Section 4.1 step 2. This step will ensure that a legacy FA will
forward the Registration Request to the Home Agent thereby making forward the Registration Request to the home agent thereby making
dynamic HA assignment possible. dynamic HA assignment possible.
Legacy Mobile Node: Legacy Mobile Node:
A MN that sends a registration request to an FA which can do dynamic An MN that sends a Registration Request to an FA that can do dynamic
HA assignment, but does not set the HA field to ALL-ZERO-ONE-ADDR HA assignment, but does not set the HA field to ALL-ZERO-ONE-ADDR
will continue to be registered with its statically configured HA, will continue to be registered with its statically configured HA,
exactly according to RFC 3344. exactly according to RFC 3344.
11. Change Log from previous versions 11. Acknowledgements
Note: This section should be removed before publication.
Changes from revision 6 to 7:
1. Updated section 4.2 bullet 5.
Changes from revision 5 to 6:
2. Updated section 4.2.1 bullet 5.
3. Fixed nits found by idnit tool.
4. Added text in section 5.1 outlining how to avoid the
possibility of multiple bindings on HAs by requiring short
lifetime for first registration request.
5. Added text in section 9 outlining possibility of multiple
bindings on HAs.
6. Added text in section 12 Acknowledgements.
Changes from revision 4 to 5:
1. Legacy FA Considerations text was updated based on the WG
discussions which addressed IESG review feedback.
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:
1. More editorial changes suggested by the chairs.
Changes from revision 1 to 2:
1. Editorial changes suggested by the WG, the chair's reviews and
idnits.
Changes from revision 0 to 1:
1. Added subtype field in Redirected HA Address Extension.
2. Aligned the HA address at 4-byte world boundary.
3. The case of handling unicast HA field is removed in section
5.3.1.
12. Acknowledgements
The authors would like to thank Pete McCann for thorough review, The authors would like to thank Pete McCann for thorough review,
suggestions on security considerations and definition of ALL-ZERO- suggestions on security considerations, and definition of ALL-ZERO-
ONE-ADDR. Thanks to Kuntal Chowdhury for extensive review and ONE-ADDR. Thanks to Kuntal Chowdhury for extensive review and
comments on this draft. Also thanks to Henrik Levkowetz for detailed comments on this document. Also thanks to Henrik Levkowetz for
reviews and suggestions. Thomas Narten highlighted issues for legacy detailed reviews and suggestions. Thomas Narten highlighted issues
FA considerations. Thanks to Ahmad Muhanna for pointing out scenario for legacy FA considerations. Thanks to Ahmad Muhanna for pointing
of multiple bindings on HAs, documented in the Security out scenario of multiple bindings on HAs, documented in the Security
Considerations section. Considerations section.
The authors would like to thank Mike Andrews, Madhavi Chandra and The authors would like to thank Mike Andrews, Madhavi Chandra, and
Yoshi Tsuda for their review and suggestions. Yoshi Tsuda for their review and suggestions.
13. Normative References 12. Normative References
[1] C. Perkins, "IP Mobility Support for IPv4", RFC 3344, August [1] Perkins, C., "IP Mobility Support for IPv4", RFC 3344, August
2002. 2002.
[2] P. Calhoun and C. Perkins, "Mobile IP Network Access Identifier
[2] Calhoun, P. and C. Perkins, "Mobile IP Network Access Identifier
Extension for IPv4", RFC 2794, March 2000. Extension for IPv4", RFC 2794, March 2000.
[3] D. Senie, "Changing the Default for Directed Broadcasts in
Routers", RFC 2644, August 1999. [3] Senie, D., "Changing the Default for Directed Broadcasts in
[4] S. Alexander and R. Droms, "DHCP Options and BOOTP Vendor Routers", BCP 34, RFC 2644, August 1999.
[4] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[5] C. Perkins and P. Calhoun, "Mobile IPv4 Challenge/Response
[5] Perkins, C. and P. Calhoun, "Mobile IPv4 Challenge/Response
Extensions", RFC 3012, November 2000. Extensions", RFC 3012, November 2000.
[6] Bradner, S., "Key words for use in RFCs to Indicate Requirement [6] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[7] C. Perkins and P. Calhoun, "AAA Registration Keys for Mobile [7] Perkins, C. and P. Calhoun, "Authentication, Authorization, and
IP", draft-ietf-mip4-aaa-key-06.txt, June 2004. Accounting (AAA) Registration Keys for Mobile IPv4", RFC 3957,
March 2005.
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
Phone:+1 408-527-8382 Phone:+1 408-527-8382
EMail: mkulkarn@cisco.com
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
Phone:+1 408-853-9580 Phone:+1 408-853-9580
EMail: alpesh@cisco.com
Kent Leung Kent Leung
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: kleung@cisco.com
Phone: +1 408-526-5030 Phone: +1 408-526-5030
EMail: kleung@cisco.com
Intellectual Property Statement Full Copyright Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC documents
can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention Copyright (C) The Internet Society (2006).
any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be required to
implement this standard. Please address the information to the IETF
at ietf-ipr@ietf.org.
Disclaimer of Validity This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
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
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 Intellectual Property
Copyright (C) The Internet Society (2005). This document is subject The IETF takes no position regarding the validity or scope of any
to the rights, licenses and restrictions contained in BCP 78, and Intellectual Property Rights or other rights that might be claimed to
except as set forth therein, the authors retain all their rights. pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Acknowledgement Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
 End of changes. 172 change blocks. 
441 lines changed or deleted 384 lines changed or added

This html diff was produced by rfcdiff 1.29, available from http://www.levkowetz.com/ietf/tools/rfcdiff/