MEXT Working Group Hong-Ke Zhang
Internet Draft Zhi-Wei Yan
Expires: March 2009 Si-Dong Zhang
Hua-Chun Zhou
Jian-Feng Guan
Beijing Jiaotong University
September 30, 2008
Router Advertisement Extension to Recognize Access Location for
Mobile Router
draft-zhang-mext-ramr-00.txt
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Abstract
The Router Advertisement message in IPv6 Neighbor Discovery Protocol
[2] contains an 8-bit field reserved for single-bit flags. Several
protocols have reserved flags in this field and others are preparing
to reserve a sufficient number of flags to exhaust the field. This
document defines a flag to the Router Advertisement message that
extends the available number of flag bits available. The extended
flag defined in this document is mainly used by Mobile Router to
identify its location.
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Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [1].
Table of Contents
1. Introduction...................................................2
2. Extended RA....................................................2
3. Security Considerations........................................5
4. References.....................................................5
Author's Addresses................................................5
Intellectual Property Statement...................................5
Full Copyright Statement..........................................6
Acknowledgment....................................................6
1. Introduction
The Router Advertisement message in IPv6 Neighbor Discovery Protocol
[2] contains an 8-bit field reserved for single-bit flags. Several
protocols have reserved flags in this field and others are preparing
to reserve a sufficient number of flags to exhaust this field.
The RA may be sent by Access Router including the Mobile Router (MR)
in mobile network. When several MR are connected in a nested manner,
they do not know the nested situation according to the basic NEMO
protocol. So it is not convenient to do some special configuration
and optimization, such as route optimization.
Routers send out Router Advertisement message periodically, or in
response to a Router Solicitation. This document defines a flag for
the Router Advertisement message. The extended format of RA is
illustrated in figure 1.
2. Extended RA
This document defines a flag for the Router Advertisement message.
The extended format of RA is illustrated in figure 1.
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cur Hop Limit |M|O|R| Reserved | Router Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reachable Time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Retrans Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Options ...
+-+-+-+-+-+-+-+-+-+-+-+-
Figure 1: Extended RA
Type
134
Code
0
Checksum
The ICMP checksum. See [ICMPv6].
Cur Hop Limit
8-bit unsigned integer. The default value that should be placed in
the Hop Count field of the IP header for outgoing IP packets. A
value of zero means unspecified (by this router).
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M
1-bit "Managed address configuration" flag. When set, hosts use the
administered (stateful) protocol for address autoconfiguration in
addition to any addresses autoconfigured using stateless address
autoconfiguration. The use of this flag is described in [ADDRCONF].
O
1-bit "Other stateful configuration" flag. When set, hosts use the
administered (stateful) protocol for autoconfiguration of other (non-
address) information. The use of this flag is described in
[ADDRCONF].
R
1-bit "Mobile Router Discovery" flag. This flag is only used by the
mobile router. When the mobile router receives a RA message
containing this flag, it will recognize that this message is sent out
by a mobile router and it they connect in a nested manner, then the
flag in its RA message should be set to 1. Otherwise, when the mobile
router receives a RA message without this flag, it will recognize it
connects to a common access router, and then the flag in its RA
message should be set to 0. So, the mobile router with this flag set
to 0 is the root mobile router, while the mobile router with this
flag set to 1 is the nested mobile router.
Reserved
A 5-bit unused field. It MUST be initialized to zero by the sender
and MUST be ignored by the receiver.
Router Lifetime
16-bit unsigned integer. The lifetime associated with the default
router in units of seconds. The maximum value corresponds to 18.2
hours. A Lifetime of 0 indicates that the router is not a default
router and SHOULD NOT appear on the default router list.
Reachable Time
32-bit unsigned integer. The time, in milliseconds, that a node
assumes a neighbor is reachable after having received a reachability
confirmation. A value of zero means unspecified (by this router).
Retrans Timer
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32-bit unsigned integer. The time, in milliseconds, between
retransmitted Neighbor Solicitation messages. A value of zero means
unspecified (by this router).
3. Security Considerations
When a malicious MR broadcast RA with the false flag, hierarchy of
nested mobile network can be confused.
4. References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998.
Author's Addresses
Hong-Ke Zhang, Zhi-Wei Yan, Hua-Chun Zhou, Si-Dong Zhang, Jian-Feng
Guan
NGI Research Center
Beijing Jiaotong University of China
Phone: +861051685677
Email:hkzhang@bjtu.edu.cn
06120232@bjtu.edu.cn
hchzhou@bjtu.edu.cn
sdzhang@center.njtu.edu.cn
guanjian8632@163.com
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