INTERNET-DRAFT S. Daniel Park Expires:October 2003 SAMSUNG Electronics Filename: Seok Joo Koh draft-park-fasthandover-agent-fmipv6-00.txt ETRI April 2003 Fast Handover Agent (FHA) for Fast Router Discovery in FMIPv6 Status of This Memo This document is an Internet-Draft and is subject to 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. Abstract This document describes a new entity "Fast Handover Agent (FHA)", which can be used for fast router discovery and configuration in FMIPv6. The FHA is deployed to provide the fast RA for Mobile Nodes entering a new IP network, without any modification of existing FMIPv6 procedures. Park & Koh [page 1] INTERNET-DRAFT Fast Handover Agent for Mobile IPv6 April 2003 Table of Contents 1. Introduction and Motivations 2. Fast Handover Agent (FHA) 3. How to use the FHA for fast router discovery 4. Further Discussions 5. Security considerations 6. References 7. Author's Addresses 1. Introduction and Motivations This document addresses the fast handover for MIPv6 (FMIPv6). One of the main issues on FMIPv6 is to reduce the time required for configuration of the router in the new access IP network, which is related to a general processing delay for the RS/RA messages, as described in [NDP]. Several approaches have been proposed for fast router discovery so far. However, most of those mechanisms are assumed to be some extra functions on the access routers (ARs) or access points (APs). This document describes a new entity "Fast Handover Agent (FHA)", which can be used for fast router discovery and configuration in FMIPv6. The FHA is deployed to provide the fast RA for Mobile Nodes entering a new IP network. It is expected that the FHAs are usually established between mobile nodes and ARs, such as AP (for 802.11) or Base Stations (for 3GPPs), for the purpose of fast processing of RS/RA messages. It is noted that the FHA does not require any modification of existing FMIPv6 procedures and systems. Accordingly, the network operators might deploy the FHAs by their own policies and associated environments. 2. Fast Handover Agent (FHA) For fast router discovery and fast handover, an FHA provides the following functions: o It must be able to receive and process the RS messages from mobile node. When a mobile node joins a new link by sending RS messages over "all router multicast address", the FHA receives the RS messages on behalf of the AR located in the network, and will respond with the corresponding RA message immediately to the mobile node. Park & Koh [page 2] INTERNET-DRAFT Fast Handover Agent for Mobile IPv6 April 2003 o It must be able to obtain the subnet-specific information such as prefix, router lifetime, address lifetime, etc) from the upper AR. o It should be able to recognize L2 triggers defined in [OPHO]. (See section 3) 3. How to use the FHA for fast router discovery This section discribes the operations of FHA-based router discovery over 802.11 networks. In 802.11, if the FHA is attached to the nearby AP, then it provides the fast handover for mobile nodes over in its own link. The FHA should be stayed in the same link as access point and router. In other words, the FHA must receive the RS message sent by mobile nodes over "all router multicast address." Figure 1 illustrates the possible deplolyment of the FHA over 802.11, where many APs are connected to a AR. The network operator can make use of FHA for each different AP, or can compose one FHA at its oveall acess network. In either case, those APs will be connected to a AR. [AR] [AR] [AR] | | | | |---[FHA] | | / \ / \ |---[FHA] / \ [FHA]---/ \---[FHA] [AP] [AP] [AP] [AP] [AP] < Figure 1 : FHA topologies > AP : Access Point AR : Access Router As described in [OPHO], when a mobile node is approaching AP, it determines that a new AP is available because it detects a beacon from the new AP. The mobile node sends management frame called "Reassociation.request" because the bit error rate on the link with the old AP has become too high. Park & Koh [page 3] INTERNET-DRAFT Fast Handover Agent for Mobile IPv6 April 2003 For the fast composition of a Care-of Address, when the FHA receives the Reassociation.request, it should send "Reassociation.reply" and the RA message simultaneously to the mobile node. [MN] [AP] [AR] <---------------------------beacon Reassociation.request------------> <--------------Reassociation.reply Link Up trigger----------> Link Up trigger RS message----------------------------------------> <----------------------------------------RA message establishing new care-of address < Figure 2 : Original L2 trigger procedure > [MN] [AP] [FHA] [AR] <---------------------------beacon Reassociation.request------------> <--------------Reassociation.reply Link Up trigger----------> <----------------------------unsolicited RA establishing new care-of address Link Up trigger RS message----------------------------------------> <---------------------------------Normal RA message < Figure 3 : L2 trigger with FHA procedure > 4. Further Discussion The other exsiting proposals for fast router discovery are assumed to be some extra functions on access router or access point. In the proposed scheme, the FHA don't need any extra functions on existing systems such as mobile node, access point and access router. Park & Koh [page 4] INTERNET-DRAFT Fast Handover Agent for Mobile IPv6 April 2003 In 3GPP, the FHA may be attached to the Base Stations for fast handover. For examples, in the 3GPP GPRS/UMTS cases, the FHA can be attached to RNC (Radio Network Controller) or SGSN(Serving GPRS Supporting Node). Similarly, in the cdma2000 case, the FHA can be attached to BSC(Base Station Controller) which performs a PCF(Packet Control Function). At this situation, the specific procedures for sending of unsolicited RA message may be different from those for the WLAN cases, according to the call flow or authentication policy used by each 3G system. The detailed issues are for further discussion. 5. Security considerations All information contained in FHA should be delegated from the upper router or similar equipment. If the malicious information are sent to FHA, it may update these informatons into its data. After all, all mobile nodes can't get correct information. As RS/RA message is described in [NDP], a host can check validity of message. If RS/RA message includes an IP Authentication Header, the message authenticates correctly. In addtion, this solution is going to be considered in SEND working group for secure messages. 6. References [NDP] T. Narten, E. Nordmark and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December, 1998. [MIPv6] D. Johnson, C. Perkins and J. Arkko, "Mobility Support in IPv6", Internet-Draft (work in progress), January 2003. [FRA] J. Kempf, M. M Khalil and B. Pentland, "IPv6 Fast Router Advertisement", Internet-Draft (work in progress), October 2002. [OPHO] Yegin, et. al. "Supporting Optimized Handover for IP Mobility - Requirements for Underlying Systems". Internet -Draft (work in progress), June 2002. [Triggers] Alper E. Yegin, "Link-layer Triggers Protocol", Internet- Draft (work in progress), June 2002. [FastRD] J. Choi, D.Shin, "Fast Router Discovery with RA Caching in AP", Internet-Draft (work in progress), February 2003. [FastHO] R.Koodli, et. al. "Fast Handovers for Mobile IPv6", Internet-Draft (work in progress), September, 2002 Park & Koh [page 5] INTERNET-DRAFT Fast Handover Agent for Mobile IPv6 April 2003 7. Author's Addresses Soohong Daniel Park Mobile Platform Laboratory, SAMSUNG Electronics, KOREA Phone: +82-31-200-3728 Email:soohong.park@samsung.com Seok Joo Koh Protocol Engineering Center, ETRI, KOREA Phone:+82-42-860-6218 Email:sjkoh@etri.re.kr Park & Koh [page 6]