Network Working Group F. Xia Internet-Draft B. Sarikaya Intended status: Standards Track Huawei USA Expires: June 4, 2007 Dec 2006 Duplicate Address Detection Optimization Using Enhanced Neighbor Discovery draft-xia-16ng-end-01 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 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 June 4, 2007. Copyright Notice Copyright (C) The IETF Trust (2006). Xia & Sarikaya Expires June 4, 2007 [Page 1] Internet-Draft Enhanced Neighbor Discovery Dec 2006 Abstract This draft describes a possible optimization to Duplicate Address Detection (DAD) which can be used to successfully terminate DAD early. The method is based on a positive RA message sent by an Neighbor Discovery Relay Agent that knows all the IPv6 addresses of the nodes currently attached to it. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Scenario of Enhanced Neighbor Discovery . . . . . . . . . . . 4 3.1. Address cache . . . . . . . . . . . . . . . . . . . . . . 4 3.2. Enhanced Relay DAD procedure . . . . . . . . . . . . . . . 4 3.3. Available Address option . . . . . . . . . . . . . . . . . 5 3.4. Timing Analysis . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Intellectual Property and Copyright Statements . . . . . . . . . . 10 Xia & Sarikaya Expires June 4, 2007 [Page 2] Internet-Draft Enhanced Neighbor Discovery Dec 2006 1. Introduction IPv6 nodes can statelessly auto configure their own IP addresses on a network, based on the information sent by the IPv6 router of that network. When a node wishes to create a new address on an interface, it combines the network prefix obtained from the router with a suffix generated from its 64-bit Interface Identifier. This new untested address is referred to as a Tentative Address (TA). The node joins the appropriate solicited-node multicast group for this address, then sends a Neighbor Solicitation (NS) message containing the TA. If the TA is already in use by another node, that node will reply with a Neighbor Advertisement (NA) defending the TA. Once it has sent the NS, the node waits for RetransTimer [DISCOVERY] milliseconds to see if a defending NA is forthcoming, and this solicit-and-wait process is repeated DupAddrDetectTransmits [DISCOVERY] times. The default value of RetransTimer is 1000ms and by default the process is only done once, resulting a delay of 1000ms or 1s. This procedure provides a reasonable approach to checking address uniqueness in situations such as fixed installation, or even mobile web-browsing where 1s is not a significant delay. However, it is not tolerable for some time-critical mobile applications like Voice Over IP (VoIP). 2. Terminology 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 BCP 14 [STANDARDS]. SS - Subscriber Station (SS) ND Relay Agent - A function entity which all SSs attach to. It maintains authoritative information about SSs' IPv6 addresses. END - Enhanced Neighbor Discovery Xia & Sarikaya Expires June 4, 2007 [Page 3] Internet-Draft Enhanced Neighbor Discovery Dec 2006 3. Scenario of Enhanced Neighbor Discovery In WiMAX architecture, A Bridge function entity is introduced in the Ethernet CS environment as per [EthernetCS]. The bridge acts as a ND Relay Agent. The ND Relay Agent knows all the IPv6 addresses of the nodes currently attached to it. 3.1. Address cache Address Cache is a conceptual data structure managed by an ND Relay Agent that contains a list of addresses that are being used by the SSs. The cache is authoritative, and how to maintain it is beyond the scope of this memo. 3.2. Enhanced Relay DAD procedure +-------+ +---------------+ +-------+ | SS1 | | ND Relay Agent| | SS2 | +-------+ +---------------+ +-------+ | | | |IPv6 Address | | |Construction | | (1) |------+ | | | | | | |<-----+ | | | | | | MLD Join | | (2) |---------------------->| | | | | | DAD NS | | (3) |---------------------->| | | |Addr. Cache Lookup | (4) | |------+ | | | | | | |<-----+ | | RA | | (5) |<----------------------| | | | | | | DAD NS | (6) | |---------------------->| | | | | DAD NA | | (7) |<----------------------|<----------------------| | | | | | | Figure 1: Enhanced Relay DAD Xia & Sarikaya Expires June 4, 2007 [Page 4] Internet-Draft Enhanced Neighbor Discovery Dec 2006 1. SS1 constructs an IPv6 Address. The address can be created as per [ADDRCONF], or other alternatives. 2. SS1 constructs a solicited node multicast address for the corresponding IPv6 Address and sends MLD Join request for the solicited node multicast address. 3. SS1 starts verifying address uniqueness by sending a DAD NS. 4. ND Relay Agent looks into the authoritative address cache to check if the address is already in use. If the address is not in use then step 5, else step 6. 5. The ND Relay Agent sends a RA with an Available Address option to indicate the uniqueness of the detected address. The detail information about the new option is described later. On receiving the positive RA, SS1 uses the address right now and stops the DAD procedure. 6. ND Relay Agent relays the DAD NS to the address owner (SS2) in case there is match in the address cache. 7. SS2 defends the address by sending DAD NA, which is relayed to SS1 via the ND Relay Agent. Upon on receiving the DAD NA, it discards the tentative address and behaves as specified in [ADDRCONF] 3.3. Available Address option 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 |P| Reserved1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + IPv6 Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 2: Available Address option Fields: Xia & Sarikaya Expires June 4, 2007 [Page 5] Internet-Draft Enhanced Neighbor Discovery Dec 2006 Type: TBD. Length: 3, in units of 8 octets. P: 1 bit. When set, indicates the uniqueness of IPv6 address carried in the option. When not set, the option should be ignored. Reserved1: 15-bit unused field. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. Reserved2: 32-bit unused field. It MUST be initialized to zero by the sender and MUST be ignored by the receiver. IPv6 Address: Available IPv6 address. 3.4. Timing Analysis In normal DAD, the process defined in [DISCOVERY] and [ADDRCONF], takes DupAddrDetectTransmits*RetransTimer before the SS can start using the address. In Optimistic DAD process [OPTDAD], as soon as an address is configured on an interface, the address can be used. That is, it takes 0 ms to use a tentative address with the risk of address collision. In case of END described in this memo, it takes a NS and RA round trip time so that an address can be determined unique in most cases. The round trip duration is much less than DupAddrDetectTransmits*RetransTimer. If END and [OPTDAD] are enabled, the SS will benefit from both the reliability and time advantages. Xia & Sarikaya Expires June 4, 2007 [Page 6] Internet-Draft Enhanced Neighbor Discovery Dec 2006 4. Security Considerations There are existing security concerns with Neighbor Discovery and Stateless Address Auto configuration. Secure Neighbor Discovery (SEND) [SEND] provides protection against the threats to Neighbor Discovery described in [NDTM]. This memo does not introduce any additional threats to Neighbor Discovery. In Relay DAD, ND Relay Agents relay NS and NA between SSs without modifying any contents of messages. The target address in Neighbor Advertisement and in solicited Router Advertisement is equal to the source address of the packet. SS can use CGAs for it's own address as defined [SEND]. SS can also use Authorization Delegation Discovery [SEND] to find an authorized ND Relay Agent. Xia & Sarikaya Expires June 4, 2007 [Page 7] Internet-Draft Enhanced Neighbor Discovery Dec 2006 5. References 5.1. Normative References [ADDRCONF] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998, . [DISCOVERY] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998, . [MLD] Vida, R., Costa, L., and B. Haberman, "Multicast Listener Discovery for IPv6", RFC 3810, June 2004, . [NDTM] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor Discovery (ND) Trust Models and Threats", RFC 3756, May 2004, . [OPTDAD] Moore, N., "Optimistic Duplicate Address Detection (DAD) for IPv6", RFC 4429, April 2006, . [PESAA] Narten, T. and R. Draves, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 3041, January 2001, . [SEND] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "Secure Neighbor Discovery (SEND)", RFC 3971, March 2005, . [STANDARDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997, . 5.2. Informative References [EthernetCS] Jeon, H., Riegel, M., and S. Jeong, "Transmission of IP Packets over Ethernet over IEEE 802.16", Oct 2006, . Xia & Sarikaya Expires June 4, 2007 [Page 8] Internet-Draft Enhanced Neighbor Discovery Dec 2006 Authors' Addresses Frank Xia Huawei USA 1700 Alma Dr. Suite 100 Plano, TX 75075 Phone: +1 972-509-5599 Email: xiayangsong@huawei.com Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 100 Plano, TX 75075 Phone: +1 972-509-5599 Email: sarikaya@ieee.org Xia & Sarikaya Expires June 4, 2007 [Page 9] Internet-Draft Enhanced Neighbor Discovery Dec 2006 Full Copyright Statement Copyright (C) The IETF Trust (2006). 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. 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