Internet DRAFT - draft-hoon-mobileip-undad
draft-hoon-mobileip-undad
IETF Mobile IP Working Group JH. Kim
Internet-Draft SAMSUNG AIT
Expires: April 15, 2004 P. Rajendran
SAMSUNG ISO
Y. Han
J. Kim
SAMSUNG AIT
October 16, 2003
Using Neighbor Caceh Entry for Duplicate Address Detection
draft-hoon-mobileip-undad-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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 http://
www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 15, 2004.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
The Duplicate Address Detection (DAD) procedure detailed by Neighbor
Discovery Protocol (NDP) requires nodes to wait for a quantified time
interval during which the configured address is checked for
duplication in the connected link. This delay affects normal
communication in a Mobile Node (MN) during the DAD time interval
thereby hampering Fast Handoff. The expected use of Mobile IP on a
wide scale and the need for a minimal time delay during the handoff
process require alternate mechanisms for overcoming the DAD time
Kim, et al. Expires April 15, 2004 [Page 1]
Internet-Draft Using NCE for DAD October 2003
interval. This draft presents a mechanism wherein the Access Router's
(AR) Neighbor Cache Entry (NCE) is used to minimize the delay
associated with the DAD procedure.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Requirements for using Neighbor Cache Entry in mobile ipv6 . . 5
3.1 Mobile Node's requirement . . . . . . . . . . . . . . . . . . 5
3.2 AR's requirement . . . . . . . . . . . . . . . . . . . . . . . 5
4. Protocol operation . . . . . . . . . . . . . . . . . . . . . . 6
4.1 Mobile node's operation . . . . . . . . . . . . . . . . . . . 6
4.2 Access Router's operation . . . . . . . . . . . . . . . . . . 6
5. Modified ICMPv6 message . . . . . . . . . . . . . . . . . . . 8
5.1 Modified NS message . . . . . . . . . . . . . . . . . . . . . 8
5.2 Modified NA message . . . . . . . . . . . . . . . . . . . . . 9
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10
Normative References . . . . . . . . . . . . . . . . . . . . . 11
Informative References . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
Intellectual Property and Copyright Statements . . . . . . . . 14
Kim, et al. Expires April 15, 2004 [Page 2]
Internet-Draft Using NCE for DAD October 2003
1. Introduction
Mobile Nodes receive Router Advertisements (RAs) from the access
routers when they roam into a foreign network. These RAs carry the
prefix information of the subnet which the MN uses to configure its
Care of Address (COA)[2]. The MN is then expected to perform normal
DAD on the connected link to ascertain the uniqueness of the COA.
This DAD time interval is expected to last a minimum of 1000ms during
which time all existing communication with the MN are paused. Only
after completion of the DAD time interval does the MN begin the Home
registration process[3]. The DAD time interval can significantly
influence the time a Mobile Node takes for Handoff thereby requiring
alternate mechanisms to minimize it.
In this document, we propose a scheme of using the Neighbor Cache
Entries (NCE) of the access router for an efficient DAD process.
Access Routers are required to perform additional functionalities in
order to maintain the complete list of nodes present in the subnet in
their Neighbor Cache. Mobile Nodes on detecting movement into a new
subnet query the Access Router about the uniqueness of the care of
address. The Access Routers check the Neighbor Cache for any matching
information and respond to the mobile nodes query. This method of
using the Neighbor Cache of the access router can support fast
hand-off by reducing DAD delay time.
Kim, et al. Expires April 15, 2004 [Page 3]
Internet-Draft Using NCE for DAD October 2003
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", "OPTIONAL", and
"silently ignore" in this document are to be interpreted as described
in RFC 2119 [1].
The following terminology and abbreviations are used in this
document.
Access Router (AR)
- Mobile node's default router which forwards IP packets not
explicitly addressed to itself.
Neighbor Cache Entry (NCE)
- A set entries about individual neighbors to which traffic has
been sent recently.
Duplicate address detection (DAD)
- Before the link-local address be assigned to an interface and
used, however, a node must attempt to verify that this
"tentative" address is not already used by some node on the
connected link.
Kim, et al. Expires April 15, 2004 [Page 4]
Internet-Draft Using NCE for DAD October 2003
3. Requirements for using Neighbor Cache Entry in mobile ipv6
Following subsections list the minimum set of requirements for
efficient DAD protocol.
3.1 Mobile Node's requirement
- A mobile node should request the access router to verify the
uniqueness of its IP address by sending a DAD NS.
- A mobile node should assign the Care of Address to its interface,
as soon as it receives NA from access router after sending NS for
DAD.
3.2 AR's requirement
- Access routers should accept and process all NS with unspecified
source address and solicited-node-multicast destination address
for DAD.
- Access router should compare the target address in the received
DAD NS message with the Neighbor cache entries to detect
duplication.
- Access routers on determining that the target address is not
present in the NC should create a new NC entry for the target
address.
- Access router should reply to the sender which has sent NS message
with the 'A' bit set in the 4th reserved field in NA if access
router has no entry corresponding to the target address.
Kim, et al. Expires April 15, 2004 [Page 5]
Internet-Draft Using NCE for DAD October 2003
4. Protocol operation
This section describes our protocol operation in detail.
4.1 Mobile node's operation
A mobile node creates a new CoA with the prefix advertised by the
access router when it moves to foreign network. The mobile node then
MUST send the modified DAD NS message to the solicited node multicast
address for DAD procedure before assigning the address to the
interface.
The modified NS message is sent with the reserved field bit set and
the mobile node waits for a NA message either from the access router
or from some other node in the same network configured with the same
address.
1) NA message from access router. - The target address in this NA
message form access router is the target address sent by the
Mobile node in its NS message. The 'A' bit is set in the message
to indicate the address's uniqueness. The 'A' bit is used to
indicate that the Access Router has no NCE corresponding to the
target address sent by the mobile node. On receipt of the modified
NA message the mobile node can send an unsolicited NA message to
the Access router to provide the MAC address.
2) NA message from existing node. - The mobile node can also receive
a NA message from another node in the network with the same
address prior to receiving the NA message from the router. In this
case the mobile node should use some other mechanism to configure
its address.
If the mobile node does not receive NA messages from either the
Access Router or some other existing node then it has to wait for
atleast 1000ms before it can configure the address to its interface.
4.2 Access Router's operation
The Access router is required to provide additional functionality in
terms of maintaining the addresses of all the connected nodes in the
link. The access router achieves this by listening to all DAD packets
in the network.
The above NS message is sent with solicited-node-multicast
destination address(FF02:0:0:0:0:1:FFXX:XXXX) and Ethernet multicast
destination address whose first two octets are the value 3333
hexadecimal and whose last four octets are the last four octets of
destination address. A access router can receive all DAD packet by
Kim, et al. Expires April 15, 2004 [Page 6]
Internet-Draft Using NCE for DAD October 2003
monitoring the fixed octets (FF02:0:0:0:0:1:FF, 3333 hexadecimal) of
solicited-node-multicast destination address and Ethernet multicast
destination address.
Once the access router receives a DAD NS message with the A bit set
it looks up its NC to determine if an entry is already present. If an
entry is not present then it sends out a NA message with the A bit
set. It also creates a new entry in its NC with the target address of
the NS message.
Kim, et al. Expires April 15, 2004 [Page 7]
Internet-Draft Using NCE for DAD October 2003
5. Modified ICMPv6 message
5.1 Modified NS message
This NS sent from MN to verify uniquness of new CoA and request to
check the NCE of access router if it has same address list as new
CoA.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Taget address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Field:
Source Address
Unspecified address.
Destination Address
Solicted-node-multicast address.
ICMP Field:
Type
135.
Code, Checksum
See [RFC2461].
'R' flag
Use the highest bit in a reserved field to
indicate that the mobile node is requesting
the access router to compare the target
address with the list of entries in the NC.
Kim, et al. Expires April 15, 2004 [Page 8]
Internet-Draft Using NCE for DAD October 2003
5.2 Modified NA message
This NA message is sent from AR if it has no entry corresponding to
New CoA.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|S|O|A| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Target Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IP Field:
Source Address
Access router's IP address.
Destination Address
Solicted-node-multicast address.
Type
136.
Code, Checksum
See [RFC 2461].
R, S, O
See [RFC 2461].
'A' flag
A bit is set when access router has no
NCE about target address of Modified NS.
Kim, et al. Expires April 15, 2004 [Page 9]
Internet-Draft Using NCE for DAD October 2003
6. Security Considerations
This draft introduces no security risks in addition to those that are
already present in the underlying protocols. However, due
consideration has to be given to the fact that a malicious node also
can receive all NS messages for DAD. It can then send out NA messages
causing the DAD of the mobile node to fail. If a malicious node sends
NS messages with different target address continuously, the access
router will create NCEs which will hamper a mobile nodes hand off.
The access routers can be provided with a NCE maintenance process to
detect such problems if it exists in the sub-network.
Kim, et al. Expires April 15, 2004 [Page 10]
Internet-Draft Using NCE for DAD October 2003
Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in
IPv6", draft-ietf-mobileip-ipv6-24 (work in progress), July
2003.
[3] Thomson, S. and T. Narten, "IPv6 Stateless Address
Autoconfiguration", RFC 2462, December 1998.
Kim, et al. Expires April 15, 2004 [Page 11]
Internet-Draft Using NCE for DAD October 2003
Informative References
[4] Moore, N., "Optimistic Duplicate Address Detection",
draft-moore-ipv6-optimistic-dad-03 (work in progress), September
2003.
[5] Han, Y., "Advance Duplicate Address Detection",
draft-han-mobileip-adad-01 (work in progress), July 2003.
Authors' Addresses
Jae-Hoon Kim
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9532
EMail: yh21.han@samsung.com
Praveen Rajendran
SAMSUNG India Software Operation
Network Systems Division
INDIA
EMail: praveen@samsung.com
Youn-Hee Han
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9233
EMail: yh21.han@samsung.com
Kim, et al. Expires April 15, 2004 [Page 12]
Internet-Draft Using NCE for DAD October 2003
Jung-Ho Kim
SAMSUNG Advanced Institute of Technology
i-Networking Laboratory
San 14-1, Nongseo-ri, Giheung-eup
Yongin-si, Gyeonggi-do 449-712
KOREA
Phone: +82 31 280 9533
EMail: kjhhjk@samsung.com
Kim, et al. Expires April 15, 2004 [Page 13]
Internet-Draft Using NCE for DAD October 2003
Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
intellectual property 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; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication 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 implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
Kim, et al. Expires April 15, 2004 [Page 14]
Internet-Draft Using NCE for DAD October 2003
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Kim, et al. Expires April 15, 2004 [Page 15]
