Internet DRAFT - draft-koodli-mip4-fmipv4
draft-koodli-mip4-fmipv4
Mobile IPv4 Working Group Rajeev Koodli
INTERNET DRAFT Charles E. Perkins
17 October 2005 Nokia Research Center
Mobile IPv4 Fast Handovers
draft-koodli-mip4-fmipv4-00.txt
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Abstract
The Mobile IPv6 fast handover document [2] specifies a protocol to
improve latency and packet loss resulting from Mobile IPv6 handover
operations. This document adapts the protocol for IPv4 networks
to improve performance over Mobile IPv4 operations, including
processing of Agent Advertisements, new Care of Address acquisition
and Registration Request and Reply. However, operation without
Foreign Agent function at a router is also feasible. In addition,
the protocol may be used transparently on hosts which do not support
Mobile IP, but with limited movement across subnets. Using the
concepts outlined in [2], this document also addresses movement
detection, IP address configuration and location update latencies
during a handover. For reducing the IP address configuration, the
document currently proposes that the new CoA is always made to be the
new access router's IP address. Additional mechanisms may be defined
in the future versions of this document.
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Contents
Abstract i
1. Introduction 2
2. Protocol Operation 2
2.1. Basic NCoA Support . . . . . . . . . . . . . . . . . . . 3
2.2. Assigned Addressing Support . . . . . . . . . . . . . . . 4
3. Use of Previous FA Notification Extension 4
4. Message Formats 4
4.1. Fast Binding Update (FBU) . . . . . . . . . . . . . . . . 4
4.2. Fast Binding Acknowledgment (FBAck) . . . . . . . . . . . 6
4.3. Router Solicitation for Proxy Advertisement (RtSolPr) . . 7
4.4. Proxy Router Advertisement (PrRtAdv) . . . . . . . . . . 9
4.5. Inter-Access Router Messages . . . . . . . . . . . . . . 11
4.5.1. Handover Initiate (HI) . . . . . . . . . . . . . 11
4.5.2. Handover Acknowledge (HAck) . . . . . . . . . . . 12
5. Option formats 14
5.1. Link-Layer Address Option Format . . . . . . . . . . . . 14
5.2. New IPv4 Address Option Format . . . . . . . . . . . . . 15
5.3. New Router Prefix Information Option . . . . . . . . . . 15
6. Security Considerations 16
7. IANA Considerations 17
Intellectual Property Statement 17
Disclaimer of Validity 18
Copyright Statement 18
Acknowledgment 18
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1. Introduction
In this document, we adapt the fast handover specification [2] to
IPv4 networks. The fast handover protocol specified in this document
is particularly interesting for operation on commonly available
wireless links such as IEEE 802.11 WLAN links. Fast handovers are
not typically needed for wired media due to the relatively large
delays attributable to establishing new connections in today's wired
networks. Mobile IPv4 registration messages are re-used (with new
type numbers) to enable quick implementation using existing foreign
agent software. This draft does not rely on link-layer triggers for
protocol operation, but performance will typically be enhanced by
using the appropriate triggers when they are available.
The active agents that enable continued packet delivery to a mobile
node are the access routers on the networks that the mobile node
connects to. Handover means that the mobile node changes its network
connection, and we consider the scenario in which this change means
change in access routers. The mobile node utilizes the access
routers as default routers in the normal sense, but also as partners
in mobility management. Thus, when the mobile node moves to a new
network, it processes handover-related signaling in order to identify
and develop a relationship with a new access router. In this
document, we call the previous access router PAR and the new access
router NAR. Unless otherwise mentioned, a PAR is also a Previous FA
(PFA) and a NAR is also a New FA (NFA).
On a particular network, the MN may obtain its IP address via DHCP
(i.e., CCoA) or use the Foreign Agent CoA. During a handover, the new
CoA is always made to be that of NAR. This allows a MN to receive and
send packets using its previous CoA, so that delays resulting from IP
configuration (such as DHCP address acquisition delay) subsequent to
attaching to the new link are disengaged from affecting the existing
sessions.
2. Protocol Operation
After a MN obtains its IPv4 care-of address, it builds a neighborhood
access point and subnet map using the Router Solicitation for Proxy
Advertisement and Proxy Router Advertisement messages. The MN may
scan for access points (APs) based on the configuration policy in
operation for its wireless network interface. If a scan results in
a new AP discovery, the MN resolves the AP-ID to subnet information
using the messages defined below.
The coordination between the access routers is done by way of the
Handover Initiate (HI) and Handover Acknowledge (HAck) messages.
After these signals have been exchanged between the previous and new
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access routers (PAR and NAR), data arriving at PAR will be tunneled
to NAR for delivery to the newly arrived mobile node. The purpose
of HI is to securely deliver the routing parameters for establishing
this tunnel. The tunnel is created by the access routers in response
to the delivery of the FBU from the mobile node.
We consider three scenarios. First, the access routers are not
involved in IP address assignment for the MN not any more than,
e.g., being a DHCP Relay when DHCP is being used. Second, an access
router acts as a foreign agent, using the same IP address for use by
a multiplicity of mobile nodes. In this scenario, an access router
provides its own IP address for the MN to use upon connecting to the
new link. Third, an access router may allocate an IP address to a
visiting mobile node by some means not specified in this document.
Just as a simple example, an access router may maintain a pool of
IPv4 addresses for temporary use by visiting mobile nodes.
The protocol semantics are almost identical in all scenarios. The
packet formats presented in RFC 3344 are re-used to achieve maximum
compatibility with Mobile IP.
2.1. Basic NCoA Support
In response to a handover trigger or indication, the MN sends a
Fast Binding Update message to Previous Access Router (PAR) (see
Section 4.1). This message should be sent when the MN is still
connected to PAR. When sent in this ``predictive'' mode, the ``Home
Address'' field must be the PCoA. The Home Agent field, even though
redundant, must be set to PAR's IP address, and the Care-of Address
must be the NAR's IP address discovered via PrRtAdv message. The
destination IP address of the FBU message must be PAR's IP address.
When attachment to a new link is detected, FBU should be (re)sent.
When sent in this ``reactive'' mode, the destination address must
be NAR's IP address, and the source address must be PCoA from the
FBU message. The Home Agent field must be set to PAR's IP address.
When NAR receives FBU, it may already have processed the HI message
and created a host route entry for the PCoA. In that case, NAR can
immediately forward arriving and buffered packets including the FBAck
message. In any case, NAR MUST forward the contents of this message,
starting from the Type field, to PAR.
The Handover Initiate (HI) and Handover Acknowledge (HAck) messages
serve to establish a tunnel between the routers to support packet
forwarding for PCoA. The tunnel itself is established as a response
to the FBU message. Furthermore, when the MN obtains a NCoA from
NAR, the reverse tunnel to the PAR is not necessary; the MN would
reverse tunnel to the Home Agent directly using its NCoA.
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The PAR sends HI message with Code = 0 when it receives FBU with
source IP address set to PCoA. The PAR sends HI with Code = 1 when
it receives FBU with source IP address not set to PCoA (i.e., when
received from NAR). This allows NAR to disambiguate processing when
HI needs to be sent as a response to predictive and reactive modes of
operation.
2.2. Assigned Addressing Support
In this mode, the NAR provides NCoA, which is delivered to the MN in
the FBAck message either on the previous link or on the new link.
Since the MN is unaware of the address that NAR might assign, it
always binds its PCoA to NAR's address. This results in a tunnel
from PAR to NAR. However, with Mobile IP, a reverse tunnel to PAR is
not necessary since the MN can directly reverse tunnel to the Home
Agent.
The source IP address in FBU is PCoA regardless of the link it is
sent from. The destination address is either PAR's IP address or the
NAR's IP address depending on the link from which FBU is sent. The
FBAck message MUST include a NCoA extension. The NAR MUST provide
NCoA in the HAck message. The NAR MUST also include the extension
when responding to FBU sent from the new link.
3. Use of Previous FA Notification Extension
Sending FBU from the new link (i.e., reactive mode) is similar to
using the extension defined in [3]. However, with the neighborhood
information gathered using the proxy router messages (see
Section 4.3, Section 4.4), movement detection and router discovery
delays are avoided even in the reactive case. The FBU and FBAck
messages defined in this document can be naturally used even when no
neighborhood information is available.
4. Message Formats
4.1. Fast Binding Update (FBU)
The FBU format is bitwise identical to the Registration Request
format in RFC 3344. The same destination port number, 434, is used,
but the FBU and FBAck messages in this specification have new message
type numbers.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type |x|x|D|M|G|r|T|x| reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Care-of Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions ...
+-+-+-+-+-+-+-+-
Figure 1: Fast Binding Update (FBU) Message
IP fields:
Source address
The interface address from which the
message is sent. Either PCoA or NAR's IP
address.
Destination Address
The IP address of the Previous Access
Router or the New Access Router.
Source Port variable
Destination port 434 (TBA)
Type To be assigned by IANA
Flags See RFC 3344
reserved Sent as zero, ignored on input
Lifetime The number of seconds remaining before binding
expires. MUST NOT exceed 10 seconds.
Home Address MUST be PCoA or the MN's Home Address
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Home Agent The Previous Access Router's global IP address
Care-of Address The New Access Router's global IP address
Identification See RFC 3344
Extensions MUST contain the MN - PAR Authentication
Extension
4.2. Fast Binding Acknowledgment (FBAck)
The FBAck format is bitwise identical to the Registration Reply
format in [4].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Home Agent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ Identification +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions ...
+-+-+-+-+-+-+-+-
Figure 2: Fast Binding Acknowledgment (FBAck) Message
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IP fields:
Source address
Typically copied from the destination
address of the FBU message
Destination Address
Copied from the Source IP address in FBU
message
Source Port variable
Destination port copied from thr source port in FBU message
Type To be assigned by IANA
Code Indicates the result of processing FBU
message. Code = 0 means Fast Binding Update
accepted. Code = 1 means Fast Binding Update
accepted but NCoA is supplied as an extension.
reserved Sent as zero, ignored on input
Lifetime The number of seconds remaining before binding
expires. MUST NOT exceed 10 seconds.
Home Address PCoA or MN's Home Address
Home Agent The Previous Access Router's global IP address
Identification a 64-bit number used for matching FBU. See RFC
3344.
Extensions The PAR - MN Authentication extension MUST be
present. In addition, a NCoA option MUST be
present when NAR supplies the NCoA.
If the FBAck message indicates that the new care-of address is a
Foreign Agent care-of address [4], then the mobile node MUST set the
'D' bit in its Registration Request message that it uses to register
the NCoA with its home agent.
4.3. Router Solicitation for Proxy Advertisement (RtSolPr)
Mobile Nodes send Router Solicitation for Proxy Advertisement in
order to prompt routers for Proxy Router Advertisements. All the
link-layer address options have the format defined in 5.1. The
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message format and processing rules are identical to that defined
in [2]. We only provide the format here for convenience.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Reserved | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
Figure 3: Router Solicitation for Proxy (RtSolPr) Message
IP Fields:
Source Address
An IP address assigned to the sending interface
Destination Address
The address of the Access Router or the all routers
multicast address.
Time-to-Live At least 1. See RFC 1256.
ICMP Fields:
Type To be assigned by IANA
Code 0
Checksum The ICMP checksum. See RFC 1256
Subtype To be assigned by IANA
Reserved MUST be set to zero by the sender and ignored by
the receiver.
Identifier MUST be set by the sender so that replies can be
matched to this Solicitation.
Valid Options:
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New Access Point Link-layer Address
The link-layer address or identification of the
access point for which the MN requests routing
advertisement information. It MUST be included
in all RtSolPr messages. More than one such address
or identifier can be present. This field can also
be a wildcard address with all bits set to zero.
4.4. Proxy Router Advertisement (PrRtAdv)
Access routers send out Proxy Router Advertisement message
gratuitously if the handover is network-initiated or as a response
to RtSolPr message from a MN, providing the link-layer address,
IP address and subnet prefixes of neighboring routers. All the
link-layer address options have the format defined in 5.1.
The message format and processing rules are identical to that defined
in [2]. We only provide the format here for convenience. The ICMP
checksum is defined in [1].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Reserved | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
Figure 4: Proxy Router Advertisement (PrRtAdv) Message
IP Fields:
Source Address
An IP address assigned to the sending interface
Destination Address
The Source Address of an invoking Router
Solicitation for Proxy Advertisement or the address
of the node the Access Router is instructing to
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handover.
Time-to-Live At least 1. See RFC 1256.
ICMP Fields:
Type To be assigned by IANA
Code 0, 1, 2, 3 or 4. See below.
Checksum The ICMP checksum. See RFC 1256.
Subtype To be assigned by IANA.
Reserved MUST be set to zero by the sender and ignored by
the receiver.
Identifier Copied from Router Solicitation for Proxy
Advertisement or set to Zero if unsolicited.
Valid Options in the following order:
New Access Point Link-layer Address
The link-layer address or identification of the
access point is copied from RtSolPr
message. This option MUST be present.
New Router's Link-layer Address
The link-layer address of the Access Router for
which this message is proxied for. This option MUST be
included when Code is 0 or 1.
New Router's IP Address
The IP address of NAR. This option MUST be
included when Code is 0 or 1.
New Router Prefix Information Option
The number of leading bits that define the network
number of the corresponding Router's IP Address
option (see above).
New CoA Option
MAY be present when PrRtAdv is sent
unsolicited. PAR MAY compute new CoA using NAR's
prefix information and the MN's L2 address, or by
any other means.
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4.5. Inter-Access Router Messages
4.5.1. Handover Initiate (HI)
The Handover Initiate (HI) is an ICMP message sent by an Access
Router (typically PAR) to another Access Router (typically NAR) to
initiate the process of a MN's handover.
The message format and processing rules are identical to that defined
in [2]. We only provide the format here for convenience.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype |S|U| Reserved | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
Figure 5: Handover Initiate (HI) Message
IP Fields:
Source Address
The IP address of the PAR
Destination Address
The IP address of the NAR
Time-to-Live At least 1. See RFC 1256.
ICMP Fields:
Type To be assigned by IANA
Code 0 or 1. See below
Checksum The ICMP checksum. See RFC 1256
Subtype To be assigned by IANA
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S Assigned address configuration flag. When set, this
message requests a new CoA to be returned by the
destination. May be set when Code = 0. MUST be 0
when Code = 1.
U Buffer flag. When set, the destination SHOULD buffer
any packets towards the node indicated in the options
of this message. Used when Code = 0, SHOULD be set
to 0 when Code = 1.
Reserved MUST be set to zero by the sender and ignored by
the receiver.
Identifier MUST be set by the sender so replies can be matched
to this message.
Valid Options:
Link-layer address of MN
The link-layer address of the MN that is
undergoing handover to the destination (i.e., NAR).
This option MUST be included so that the destination
can recognize the MN.
Previous Care of Address
The IP address used by the MN while
attached to the originating router. This option
SHOULD be included so that host route can be
established in case necessary.
New Care of Address
The IP address the MN wishes to use when
connected to the destination. When the `S' bit is
set, NAR MAY assign this address.
4.5.2. Handover Acknowledge (HAck)
The Handover Acknowledgment message is a new ICMP message that MUST
be sent (typically by NAR to PAR) as a reply to the Handover Initiate
(HI) (see section 4.5.1) message.
The message format and processing rules are identical to that defined
in [2]. We only provide the format here for convenience.
IP Fields:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Code | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subtype | Reserved | Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
Figure 6: Handover Acknowledge (HAck) Message
Source Address
Copied from the destination address of the Handover
Initiate Message to which this message is a
response.
Destination Address
Copied from the source address of the Handover
Initiate Message to which this message is a
response.
Time-to-Live At least 1. See RFC 1256.
ICMP Fields:
Type To be assigned by IANA
Code
0: Handover Accepted, NCoA valid
1: Handover Accepted, NCoA not valid
2: Handover Accepted, NCoA in use
3: Handover Accepted, NCoA assigned
(used in Assigned addressing)
4: Handover Accepted, NCoA not assigned
(used in Assigned addressing)
128: Handover Not Accepted, reason unspecified
129: Administratively prohibited
130: Insufficient resources
Checksum The ICMP checksum. See RFC 1256.
Subtype To be assigned by IANA.
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Reserved MUST be set to zero by the sender and ignored by
the receiver.
Identifier Copied from the corresponding field in the Handover
Initiate message this message is in response to.
Valid Options:
New Care of Address
If the S flag in the Handover Initiate message is set,
this option MUST be used to provide NCoA the MN should
use when connected to this router. This option MAY be
included even when `S' bit is not set, e.g., Code 2
above.
5. Option formats
The options in this section are specified as optional extensions
for the HI and HAck messages, as well as for the Router Proxy
Solicitation and Router Proxy Advertisement messages..
5.1. Link-Layer Address Option Format
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Link-Layer Address ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Link-Layer Address Option Format
Fields:
Type
1 Mobile Node Link-layer Address
2 New Access Point Link-layer Address
3 NAR Link-layer Address
Length The length of the option (including the type and
length fields) in units of octets. For example,
the length for IEEE 802 addresses is 1 [IPv6-
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ETHER].
Link-Layer Address
The variable length link-layer address.
The content and format of this field (including
byte and bit ordering) depends on the specific
link-layer in use.
5.2. New IPv4 Address Option Format
This option is used to provide the new router's IPv4 address in
PrRtAdv. When it is also used to provide NCoA, it MUST appear after
the new router's IPv4 address to distinguish the two addresses.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| New IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: New IPv4 Address Option Format
Fields:
Type
To be assigned by IANA
Length The length of the option (including the type and
length fields) in units of octets.
Reserved Set to zero.
NCoA The New CoA assigned by NAR.
5.3. New Router Prefix Information Option
This option is the same as the ``Prefix-Lengths Extension'' in RFC
3344 (Section 2.1.2).
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix-Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 9: New Router Prefix Information Option Format
Fields:
Type
To be assigned by IANA
Length 1
Prefix-Length
The number of leading bits that define the network
number of the corresponding Router's IP Address
option.
Reserved Set to zero.
6. Security Considerations
The FBU and FBack messages MUST be protected using a security
association shared between a MN and its access router. In
particular, the MN - PAR Authentication Extension MUST be present in
each of these messages. Failure to include this extension can lead
to a bogus node claiming a genuine MN's address and binding it to
an arbitrary address. When the NCoA is NAR's address, there is no
risk of a genuine MN misdirecting traffic, either inadvertantly or
intentionally, to an unsuspecting node on NAR's subnet. When NCoA is
other than NAR's address, NAR MUST ensure that the proposed NCoA in
HI is conflict-free, and MUST indicate the disposition in the HAck
message. If there is a conflict, PAR MUST NOT tunnel packets to
the address in question. Instead, PAR SHOULD tunnel packets to the
address specified in HAck, if any is provided.
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7. IANA Considerations
All the messages and the option formats specified in this document
require Type assignment from IANA.
References
[1] S. Deering. ICMP Router Discovery Messages. Request for
Comments (Proposed Standard) 1256, Internet Engineering Task
Force, September 1991.
[2] R. Koodli (Editor). Fast Handovers for Mobile IPv6 (work in
progress). Internet Draft, Internet Engineering Task Force.
draft-ietf-mipshop-fast-mipv6-03.txt, October 2005.
[3] C. Perkins and D. Johnson. Route Optimization in Mobile IP (work
in progress). Internet Draft, Internet Engineering Task Force.
draft-ietf-mobileip-optim-09.txt, February 2000.
[4] C. Perkins (Editor). IP Mobility Support for IPv4. Request for
Comments (Proposed Standard) 3344, Internet Engineering Task
Force, August 2002.
Questions about this memo can be directed to the authors:
Rajeev Koodli Charles E. Perkins
Communications Systems Lab Communications Systems Lab
Nokia Research Center Nokia Research Center
313 Fairchild Drive 313 Fairchild Drive
Mountain View, California 94043 Mountain View, California 94043
USA USA
Phone: +1-650 625-2359 Phone: +1-650 625-2986
EMail: rajeev.koodli@nokia.com EMail: charliep@iprg.nokia.com
Fax: +1 650 625-2502 Fax: +1 650 625-2502
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Koodli, Perkins Expires 17 April 2006 [Page 17]
Internet Draft Fast Handovers for Mobile IPv4 17 October 2005
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