Internet Engineering Task Force J. Tian Motorola Internet Draft A.Helal Document: draft-tian-sa-mip-00.txt University of Florida Expires: November 1 2006 May 2006 MIP SPEED EXTENSION 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 November 1, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The speed extension to the Mobile Internet Protocol provides a way for the Foreign Agents and Home Agents to perceive the moving speed of the Mobile Nodes. With the speed information popularized in the mobile IP network, the behavior of the Mobile IP implementation with speed adaptive algorithm implemented will automatically adapt to the speed of the Mobile Node so that the performance of the Mobile IP won’t decline dramatically in a rapid moving environment. At the same Tian & Helal Expires - November 2006 [Page 1] MIP SPEED EXTENSION May 2006 time, the Mobile IP speed adaptive algorithm only requires reasonable resources that are enough for seamless handoff. 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 RFC-2119 [i]. Table of Contents 1. Introduction...................................................2 2. Performance of MIP and the moving speed of MN..................3 2.1 Performance of MIP at different moving speeds..............3 2.2 Relationship between Performance of MIP and moving speeds of MN.............................................................3 3. Speed adaptive MIP (SA-MIP)....................................4 3.1 Foreign Agent set size.....................................4 3.2 MIP speed extension........................................5 3.3 SA-MIP handoff procedure...................................6 4. Security Considerations........................................6 References........................................................7 Author's Addresses................................................7 Full Copyright Statement..........................................7 Acknowledgments...................................................8 1. Introduction While TCP/IP successfully overcomes the barriers of time and distance in a wired network, mobile IP is a promising technology to eliminate the barrier of location for the increasing wireless internet usage. Third generation (3G) services combine high speed mobile access with IP-based services. 3G networks are based on a set of radio technology standards such as CDMA2000, EDGE and WCDMA. Mobile IP (MIP) can be used as the common macro mobility management framework to merge all these technologies and allow mobile users to roam between different access networks. Throughout history, the economic wealth of people or a nation has been closely tied to transportation efficiency. A person can drive a car on high way at speed of 80miles/h. Some high speed trains such as France TGV, Japanese bullet, German maglev can travel at speeds of over 200 miles/h. Could people surf the internet, communicate with families and enjoy an online movie while traveling at high speeds? Could the current network infrastructure support rapid mobility? A review on recent research on MIP shows a great amount of efforts contributed to reducing MIP handoff latency. [1] proposed two Tian & Helal Expires - November 2006 [Page 2] MIP SPEED EXTENSION May 2006 mobility protocols, pre- and post-registration, using L2 trigger. In pre- registration, MN may communicate with both oFA (old Foreign Agent) and nFA (new Foreign Agent). In post-registration, data are cached in nFA before the registration is completed. Fast-handover [2] for Mobile IPv6 network combines the about two methods. But they all depend on L2 (layer 2). S-MIP[3], uses MN location and movement patterns to ‘instruct’ the MN when and how handoff should be carried out. [4] also uses MN’s movement model to predict handoff. But all these efforts didn’t consider the speed factor of MN, which may cause problems when the MN moving rapidly. 2. Performance of MIP and the moving speed of MN MIPv4[5] is designed independently from all Layer 2 technologies. In order to evaluate the performance of MIP in rapid moving environments, without losing generality, 802.11b is used as the Layer 2 technology to evaluate the performance of MIP. 2.1 Performance of MIP at different moving speeds The experiment results shows that the time-sequence graph and throughput graph at speed 20m/s and Access Point(AP) distance 1000m are similar to those graphs at speed 10m/s and AP distance 500m. Also the time-sequence graph and throughput graph at speed 80m/s and AP distance 1000m are similar to those graphs at speed 40m/s and AP distance 500m, as well as those graphs at speed 20m/s and AP distance 250m. If double the moving speed of MN and at the same time double the AP distance, the average throughput shows no suggestive difference. 2.2 Relationship between Performance of MIP and moving speeds of MN The experiment also shows that the handoff overall time doesn’t change with speed and effective time/total travel time ratio decreases when the speed increases. Let Pavg – Average throughput Pmaxavg – Average throughput without handoff Ttravel – Total travel time Teffective – Total effective time for ftp transmission Thandoff – Total handoff time while traveling Khandoff – The number of handoffs while traveling thandoff – Average handoff time among 7 times of handoff Then, Pavg = (Pmaxavg / Ttravel ) x Teffetive = Pmaxavg (Ttravel – Thandoff )/ Ttravel = Pmaxavg (1 – Thandoff / Ttravel) = Pmaxavg( 1 – Khandoff x thandoff / Ttravle) = Pmaxavg( 1 – (Khandoff / Ttravle ) x thandoff )) Tian & Helal Expires - November 2006 [Page 3] MIP SPEED EXTENSION May 2006 Since thandoff doesn’t change, The change of Pavg is caused by Khandoff/Ttravel ratio. Define MN handoff rate as rh = v/d, which is the ratio of the MN’s speed and the cell size(AP distance). It means that how many APs or FAs the MN hands over in one second. rh is also equal to Khandoff / Ttravel. The relationship between the performance of MIP over WLAN and the moving speed is presented in the following equation: Pavg = Pmaxavg( 1 – rh x thandoff ) (1) Where Pavg is the average throughput for the MN; Pmaxavg is the average throughput without handoff. thandoff is the average handoff time (in second) for every handoff procedure. 3. Speed adaptive MIP (SA-MIP) Equation 1 shows that the performance of MIP depends on the MN handoff rate. rh is also equal to the ratio of Khandoff/Ttravel, where Khandoff is the number of handoffs occurred during the MN traveling. Ttravel is MN’s total travel time. To reduce rh without changing total travel time, the number of handoffs needs to be reduced. The optimal is Khandoff = 0 3.1 Foreign Agent set size. Let N be the total FA numbers on the way MN travels. Let’s assume M is the number of FAs with whom the MN can communicate without L3 handoff delay. The optimal is let M = N. But this costs too many resources, especially when the number of active MNs is large. It's hard to know how long the MN will travel at the beginning. Let M be the size of the FA Set with whom the MN can communicate without L3 handoff delay. From IP level of view, M is the number of FAs that MN has registered to and can communicate with at that moment. Now the question is: 1. How to decide FA set size M 2. How to guarantee MN can communicate with a FA set almost like to do with a single FA. For question 1, equation 6 gives the FA set size. M = | thandoff x rh | + 1 (2) Tian & Helal Expires - November 2006 [Page 4] MIP SPEED EXTENSION May 2006 In this equation, thandoff is the handoff time for every handoff procedure, and rh is the handoff rate. The value of thandoff can be an experimental measurement result. rh is dynamic. For question 2, the solution is to let MN pre-register M potential FAs along the way MN travels, at the same time let IP packets be multicasted to those M FAs in this FA set. So MN will not experience any handoff delay from the IP level of view. In SA-MIP, the set of FAs that MN can talk to without L3 latency is extended from one point at low moving speed to a line at high moving speed. The length of the line dynamically changes with the MN handoff rate. The behavior of SA-MIP will automatically adapt to the handoff rate of the MN so that the performance of SA-MIP won’t decline dramatically in a rapid moving environment. At the same time, SA-MIP only cost reasonable amount of resource that is appropriate for seamless handoff. 3.2 MIP speed extension MN’s registration message is extended by speed extension. According to Mobile IP Vendor/Organization-Specific Extensions[6]. Two Vendor/Organization Specific Extensions are allowed for MIP, Critical (CVSE) and Normal (NVSE) Vendor/Organization Specific Extensions. The basic difference is when the CVSE is encountered but not recognized, the message containing the extension must be silently discarded, whereas when a NVSE is encountered but not recognized, the extension should be ignored, but the rest of the Extensions and message data must still be processed. the NVSE extension format is use for the speed extension. The format of the speed extension is as shown below. It follows the format of NVSE extension. 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 = 134 | Length | reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor/Org-ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Speed-Type | Speed-Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: Normal Vendor/Organization Specific Extension Type NVSE-TYPE-NUMBER 134 Tian & Helal Expires - November 2006 [Page 5] MIP SPEED EXTENSION May 2006 Length Length in bytes of this extension, not including the Type and Length bytes. Reserved Reserved for future use. To be set to 0. Vendor/Org-ID The high-order octet is 0 and the low-order 3 octets are the SMI Network Management Private Enterprise Code of the Vendor in network byte order, as defined in the Assigned Numbers RFC [7]. 5400 may be used here. Speed-Type Indicates the type of speedExtension. Number 10 indicates the Speed-Value is an absolute speed value. Number 11 indicates the Speed-Value is value of handoff rate in FAs/second. Speed-Value When the Speed-Type is 10, this value is an absolute speed value in meters/second. When the Speed-Type is 11, this value is a handoff rate in FAs/second. 3.3 SA-MIP handoff procedure Whenever the MN needs to handoff to a new FA set, after it gets a new agent advertisements, it sends a registration request with up-to-date speed or handoff rate information to the very first FA in a new FA set. The first FA relays the registration request to upper FA or HA. Meanwhile, it decapsulates the speed extension, refill the MIP header and authentication extension and then forward it to other FAs(M-1 FAs) in this FA set. These other FAs relay the registration request to upper FA or HA as well, just like the request comes from the MN. When the GFA or HA received these registration requests, it builds up tunnels downwards to each FA and responses with a registration reply. When the FA received the registration reply, it builds up tunnel upwards to the GFA or HA. Whenever the MN setups the Link-layer contact with the FA, the later forwards the registration reply to the former. The MN gets the care-of-address from agent advertisement message or registration reply message, and begins data communication. At the same time, it sends registration request to the new FA with up-to-date speed or handoff rate information. This new FA decapsulates the registration request message and sets up a new FA set. The new FA refill the MIP header and authentication extension and then forward it to other FAs in this FA set and repeats the above process. 4. Security Considerations This document assumes that the MIP registration messages with speed extension are authenticated using a method defined by the Mobile IP protocol. This document does not impose any additional requirements Tian & Helal Expires - November 2006 [Page 6] MIP SPEED EXTENSION May 2006 on Mobile IP messages from a security point of view. So this is not expected to be a security issue. References [1] K. El Malki et al., “Low latency handoffs in mobile IPv4”,IETF draft-ietf-monileip-low-latency - handoffs -v4-04.txt, 2002 [2] R. Koodli, "Fast Handovers for Mobile IPv6" IETF draft-ietf- mobileip-fast-mipv6-08.txt, 2003 [3] R.Hsieh, G.Zhou, and A.Seneviratne, S-MIP: "A Seamless Handoff Architecture for Mobile IP". Proceedings of INFOCOM, San Francisco, 2003 [4] N.Van den Wijngaert, and C.Blondia, “An Urban Mobility Model and Predictive Hando ver Scheme for Mobile IP”, Proceedings of OPNETWORK 2004, Washington D.C., 2004. [5] C.Perkins,RFC3344,“IP Mobility Support for IPv4”, August 2002. [6] G. Dommety K. Leung, "Mobile IP Vendor/Organization-Specific Extensions" RFC 3115, April 2001. [7] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC 1700, October 1994 Author's Addresses Jun Tian Motorola 600 North U.S. Highway 45, MS:AN2 Libertyville, IL 60048 Phone: 847-877-5809 Email: jacky.tian@motorola.com Abdelsalam (Sumi) Helal University of Florida P.O. Box 116120 Gainesville, Florida 32611-6120 Phone: 352-392-6845 Email: helal@cise.ufl.edu Full Copyright Statement Copyright (C) The Internet Society (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and Tian & Helal Expires - November 2006 [Page 7] MIP SPEED EXTENSION May 2006 except as set forth therein, the authors retain all their rights. "This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgments The authors would like to thank Janise McNair, Dapeng Wu, Paul Fishwick and Markus Schneider for their useful discussions. Tian & Helal Expires - November 2006 [Page 8]