Mobile IP Working Group Jari T. Malinen INTERNET DRAFT Charles E. Perkins 1 March 2001 Nokia Research Center Category: Standards Track Mobile IPv6 Regional Forwarding draft-malinen-mobileip-reg6fwd-00.txt Status of This Memo This document is a submission by the mobile-ip Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the MOBILE-IP@STANDARDS.NORTELNETWORKS.COM mailing list. Distribution of this memo is unlimited. 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. Abstract Data forwarding to a Mobile IPv6 mobile node employs either encapsulation or routing header -based forwarding, latter when using route optimization. Forwarding through a domain with hierarchical extensions to Mobile IPv6 by default uses encapsulation to pass route-optimized packets over the last hop to the mobile node. However, it is highly desirable to avoid the overhead of sending an extra 40 byte encapsulation header per packet over the last hop. This document describes Mobile IPv6 regional forwarding which is an optional optimized data forwarding method. It avoids the encapsulation header and can be used e.g. with Mobile IPv6 Regional Registrations. Malinen, Perkins Expires 1 November 2001 [Page 1]
Internet Draft Mobile IPv6 Regional Forwarding 1 March 2001 Contents Status of This Memo 1 Abstract 1 1. Introduction 2 2. Terms 3 3. Protocol Operation 3 4. New requirements for IPv6 Nodes 4 4.1. Visited Domain Router Requirements . . . . . . . . . . . 5 4.2. Mobile Node Requirements . . . . . . . . . . . . . . . . 5 5. Security Considerations 5 6. Intellectual Property Right Considerations 5 Addresses 6 1. Introduction Conserving last hop bandwidth is a major design goal in several types of radio access networks. When using localized mobility extensions to the Mobile IPv6 [2], such as Mobile IPv6 Regional Registrations [5], the default propagation method uses encapsulation. Packets coming from the corresponding node to the mobile node are route-optimized after the corresponding node has received a binding update. Almost all of the data traffic is route-optimized, since the mobile node sends a binding update to a corresponding node soon after receiving packets from the corresponding node, tunneled by the home agent. Each route-optimized packet carries a routing header with the home address in it and is destined to the registered care-of-address. When a localized mobility scheme is used, the care-of-address registered at the home network points to a gateway mobility agent. This receives the route-optimized data packet, processes the routing header, and then needs to find a route to the home address. Since link-distance cannot be guaranteed between regional-aware routers, or the gateway mobility agent and the mobile node, a host route to the home address points to a tunnel interface. This results in encapsulation of the route-optimized packet to the mobile node. Malinen, Perkins Expires 1 November 2001 [Page 2]
Internet Draft Mobile IPv6 Regional Forwarding 1 March 2001 Such an encapsulation contains the outer encapsulation header, 40 bytes, in addition to the routing header. To get rid of the extra encapsulation, our proposed protocol forwards the packet from the gateway down to the mobile node by making a slight change to the way routing headers are processed. The forwarding node inserts the care-of-address from the regional binding cache into the IP destination address. Application of this operation in visited domain routers eventually propagates the packet unencapsulated down to the mobile node. For authentication purposes, the mobile node finally returns the regional care-of-address to the IP destination address. 2. Terms 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 [1]. In addition, this document uses the following terms: Regional-aware Router A router following this specification. Regional Forwarding Forwarding of packets through a hierarchy of mobility agents such that the binding cache entries in the regional mobility agents are used for packet forwarding. This terminology is intended to conform to those that have been used in Mobile IP and other Internet protocols. Basic Mobile IPv6 terminology is used as defined in [2] and [5]. 3. Protocol Operation When a corresponding node sends data packets to a mobile node to which it does not yet have an entry in its binding cache, these packets are intercepted by the home agent and encapsulated to the registered care-of-address mobile node, as specified in the basic Mobile IPv6. However, this care-of-address is the regional care-of-address. When a corresponding node has received a binding update, it knows the regional care-of-address and sends packets to the mobile node using this address as the destination address. The corresponding node includes a type 0 routing header to the packet so that the home Malinen, Perkins Expires 1 November 2001 [Page 3]
Internet Draft Mobile IPv6 Regional Forwarding 1 March 2001 address of the mobile node is the only entry in the routing header, as specified in the basic Mobile IPv6. A regional-aware router forwards a packet to the next lower regional-aware router in a special way. If there is an entry in the regional binding cache for the home address in the routing header, the routing header is kept in its original state. That is, the home address remains in the routing header entry, and the `segments left' field is not decreased. The packet is then forwarded using the regional binding cache entry. The destination address of the packet is replaced with the care-of-address in the regional binding cache and the packet is then submitted back to the IP forwarding engine for further processing. When the mobile node receives the packet that has been forwarded using regional-aware data routing, it consumes the routing header after swapping the regional care-of-address as the IP destination. The mobile node sets the destination to be the home address, swaps the regional care-of-address from the binding update list to the place of the home address in the routing header, and finally decreases the segments left prior to submitting the packet to IPSec. The authentication header [4] integrity check calculation is then identical to what would be needed in a basic Mobile IP mobile node. From the received packet the mobile node also observes if packets have the encapsulation or routing header and can distinguish whether to send a binding update to a corresponding node, as in basic Mobile IPv6. When the mobile node sends packets to a correspondent node, the source address is the primary care-of-address of the mobile node, and the destination address is the corresponding node. The packets contain the home address extension [3]. Thus, routing towards the correspondent node occurs exactly as with the basic Mobile IPv6. 4. New requirements for IPv6 Nodes The presented option requires modifications to the visited-domain routers and to the mobile node. The option does pose no new requirements to the home agent, to correspondent nodes, or to other network elements than to the regional-aware routers in the visited domain and the mobile node. Malinen, Perkins Expires 1 November 2001 [Page 4]
Internet Draft Mobile IPv6 Regional Forwarding 1 March 2001 4.1. Visited Domain Router Requirements The support of the protocol is optional. The visited domain router needs a modification to the routing header processing such that a binding cache lookup precedes normal routing header processing. If a care-of-address is found for the address in the routing header, no further routing header processing is done and the care-of-address is inserted to the destination address of the IP header. The protocol modifies the routing engine, but the only modification needed is almost trivial to a software-based IPv6 forwarding engine. 4.2. Mobile Node Requirements A regional-aware mobile node needs to perform the same operation for received packets as a visited domain router does. This ensures the packet is correct for authentication. A lookup based on a home address in a mobile node is fast because there usually are not many home addresses in a mobile node. 5. Security Considerations The regional-aware mobile uses IPsec authentication header for security as in basic Mobile IPv6. The mobile node modification is needed to make the authentication header integrity check value (ICV) calculation to succeed. This is achieved by returning the packet to such a state that it contains the same immutable elements as were in the packet when computing the AH ICV field by the sender. 6. Intellectual Property Right Considerations Nokia Corporation and/or its affiliates hereby declare that they are in conformance with Section 10 of RFC 2026. Nokia's contributions may contain one or more patents or patent applications. To the extent Nokia's contribution is adopted to the specification, Nokia undertakes to license patents technically necessary to implement the specification on fair, reasonable, and nondiscriminatory terms based on reciprocity. Malinen, Perkins Expires 1 November 2001 [Page 5]
Internet Draft Mobile IPv6 Regional Forwarding 1 March 2001 References [1] S. Bradner. Key words for use in RFCs to Indicate Requirement Levels. Request for Comments (Best Current Practice) 2119, Internet Engineering Task Force, March 1997. [2] D. Johnson and C. Perkins. Mobility Support in IPv6 (work in progress). Internet Draft, Internet Engineering Task Force, November 2000. [3] D. Johnson and C. Perkins. Mobility Support in IPv6 (work in progress). draft-ietf-mobileip-ipv6-13.txt, October 2000. [4] S. Kent and R. Atkinson. IP Authentication Header. Request for Comments (Proposed Standard) 2402, Internet Engineering Task Force, November 1998. [5] J. Malinen and C. Perkins. Mobile IPv6 Regional Registrations (work in progress). Internet Draft, Internet Engineering Task Force, March 2001. Addresses The working group can be contacted via the current chairs: Basavaraj Patil Phil Roberts Nokia Corporation Motorola 6000 Connection Drive 1501 West Shure Drive M/S M8-540 Irving, Texas 75039 Arlington Heights, IL 60004 USA USA Phone: +1 972-894-6709 Phone: +1 847-632-3148 Fax : +1 972-894-5349 EMail: Basavaraj.Patil@nokia.com EMail: QA3445@email.mot.com Questions about this memo can also be directed to the authors: Jari T. Malinen Charles E. Perkins Communications Systems Lab Communications Systems Lab Nokia Research Center Nokia Research Center 313 Fairchild Drive 313 Fairchild Drive Mountain View, California 94043 Mountain View, California 94043 USA USA Phone: +1-650 625-2355 Phone: +1-650 625-2986 EMail: jmalinen@iprg.nokia.com EMail: charliep@iprg.nokia.com Fax: +1 650 625-2502 Fax: +1 650 625-2502 Malinen, Perkins Expires 1 November 2001 [Page 6]