INTERNET DRAFT Pete McCann Category: Lucent Technologies Title: draft-mccann-mobileip-sessionid-00.txt Kent Leung Date: March 2000 Cisco Systems Mobile IP Session Identifier Extension draft-ietf-mobileip-sessionid-00.txt Status of this Memo This document is an Internet Draft and is in full compliance 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. Internet Drafts 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 The Network Access Identifier can be added to a Mobile IP registration request to identify the user and to allow the assignment of a dynamic home address. However, users may want to open several simultaneous sessions using the same NAI from the same or different devices and to obtain a unique IP address for each session. The Mobile IP Session Identifier Extension defined in this draft can be used to distinguish registration requests belonging to these various sessions. This draft also clarifies how a dynamic address is to be managed when and if the user returns to the home network that assigned the address. 1. Introduction A Mobile IP Registration Request may carry a Network Access Identifier (NAI) [1,2] that serves to identify the user requesting access to the network. However, a given user may want to open McCann and Leung Expires 09/2000 1 INTERNET DRAFT Mobile IP Session ID Extension March 2000 multiple, simultaneous Mobile IP sessions from the same or different devices, using the same NAI, and the user may desire to use a dynamic home address on each. For these situations some mechanism is needed to distinguish the registration requests pertaining to the different sessions. This document proposes a Session Identifier Extension to Mobile IP that can play this role. When it is included in each Registration Request sent by a mobile node, a user can have multiple active Mobile IP sessions, each with a different Home Address, while using the same NAI and Home Agent. A user may need to continue using an assigned address independent of any mobility bindings for that address. For example, when a dynamically addressed MN returns home, it may want to de-register all care-of addresses but continue to use the assigned address on the home network. This document proposes procedures to be followed by the MN and HA that allow the allocated address to be managed independently of any mobility bindings. When these procedures are followed a dynamically addressed MN may enjoy continuous service even when returning to the home network. 2. Session Identifier Extension The Session Identifier extension MAY be attached to the registration request and/or reply. It is defined as follows: 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 | Sub-Type | rsv | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Session ID... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type Skippable (TBD) Length Length in bytes of this extension, not including the Type and Length bytes. Sub-Type A number assigned to identify the Session ID type. Currently this field MUST be set to zero. Future drafts may specify other values and associated meanings for this field. rsv McCann and Leung Expires 09/2000 2 INTERNET DRAFT Mobile IP Session ID Extension March 2000 Reserved for future use. MUST be set to 0 on sending, MUST be ignored on reception. Session ID The Session ID field is one or more octets that identifies the session for which the mobile node is registering. There are no restrictions on the contents of the Session ID field. For example, it MAY contain ASCII character strings or globally unique identifiers in ASN.1 syntax. The Session ID should not be NUL or CR/LF terminated. The size is determined from the Length field. 3. Mobile Node Considerations The Session Identifier Extension contains a value that distinguishes the Registration Request as belonging to a particular session. The MN should choose a suitable value for this field at the beginning of a session and consistently place the same value in any subsequent Registration Requests pertaining to that session. If the MN sets teh Home Address field to zero, it is requesting that the HA assign an address and return it in the Home Address field of the Registration Reply. If the MN includes a nonzero value in the Home Address field, it MUST use an address that was previously (dynamically or statically) allocated to the same Session ID. When the Session Identifier Extension is present in the Registration Request it MUST appear in the Registration Request before both the Mobile-Home Authentication extension and Mobile-Foreign Authentication extension, if present. If the MN wishes to continue using a dynamically assigned address even after de-registering with its HA, it MUST follow the procedures outlined in Section 6. 4. Foreign Agent Considerations If the Home Address is zero in the Registration Request, and the Session Identifier Extension is present, the foreign agent MUST use the NAI provided by the NAI extension [1] and the Session ID provided by the Session Identifier Extension to index its pending registration request records. If the foreign agent cannot manage pending registration request records in this way, it MUST return Registration Reply with Code NONZERO_HOMEADDR_REQD [1]. If the mobile node includes the Session Identifier Extension in its Registration Request, then the corresponding Registration Reply from the Home Agent MUST include the same Session Identifier Extension. If not the foreign agent SHOULD send the Registration Reply to the mobile node, changing the Code to the value MISSING_SESSION_ID (see section 7). McCann and Leung Expires 09/2000 3 INTERNET DRAFT Mobile IP Session ID Extension March 2000 5. Home Agent Considerations If the mobile node includes the Session Identifier Extension in its Registration Request, then the corresponding Registration Reply from the home agent MUST also include the same Session Identifier Extension. If the Registration Request received by the HA has a Home Address field set to zero, the HA will attempt to allocate an IP address for the MN at the home domain and return it in the Home Address field of the Registration Reply. If the home agent could not allocate an IP address for the mobile node or if the given address was already allocated to a different session it MUST return a Registration Reply with code CANNOT_ALLOC_IP (see section 7). If the HA returns a dynamically allocated IP address, it is the responsibility of the HA to ensure that the address is not allocated to any other node for the duration of the established Mobile IP Lifetime. To ensure that the MN receives continuous service even after returning home, the HA MUST support the procedures outlined in Section 6. 6. Address Management If all of the registrations for a given home address expire, then the home agent will release all the resources allocated for the MN including any dynamically allocated IP address. However, some new mechanism is needed to support continued use of the address even when no care-of addresses are registered such as when the MN has de- registered after returning home. When the MN wishes to de-register, it should send a Registration Request to the HA as follows: - If the MN has a statically allocated home IP address, it sets the fields of the Registration Request as outlined in basic Mobile IP [3]. - If the MN has a dynamically allocated home IP address and wishes to release all resources including its dynamically allocated IP address, it sets the Care-of Address field to its allocated home address and the Lifetime field to zero. - If the MN has a dynamically allocated home IP address and wishes to release all mobility bindings but wishes to keep the allocated IP address for use on the home network, it sets the Care-of Address field to zero (0.0.0.0) and also sets the Lifetime field to zero. The HA will cease to tunnel traffic but will continue to ensure that the assigned IP address is not McCann and Leung Expires 09/2000 4 INTERNET DRAFT Mobile IP Session ID Extension March 2000 allocated to any other node for the duration of the previously established Mobile IP Lifetime. - If the MN has a dynamically allocated home IP address and wishes to de-register only one mobility binding, but not the allocated home address and not other mobility bindings, it sets the Care-of Address field to the binding it wishes to de- register and the Lifetime field to zero. This does not release the allocated address. - If the MN has a dynamically allocated home IP address and wishes to extend the use of the address without affecting any mobility bindings that may be in place, it sets the Care-of Address field to its allocated home address and the Lifetime field to a value greater than zero. As an example, assume that the MN powers up and connects to some FA. Since it does not yet have an address, it sets the Home Address field to zero (0.0.0.0), the Care-of Address to that of the FA, and sets the NAI, Session ID, and Lifetime to appropriate values. The HA allocates an address and returns it. Later, the MN moves back to the home network. It de-registers its mobility binding by sending a Registration Request to the HA with the Care-of Address set to the FA's address and the Lifetime set to zero. Although this removes the mobility binding, the MN's home address is still reserved for the remaining Lifetime that was previously established. The MN may periodically renew use of the address before it expires by sending a Registration Request to the HA with Care-of Address set to the allocated home address and the Lifetime set to an appropriate value. The MN may explicitly release the address by sending a Registration Request with Care-of Address set to the allocated home address and the Lifetime set to zero. 7. Error Values The following table contains the error Code [3] to be returned in the Registration Reply, the value for the Code, and the section in which it is first mentioned. Error Name Value Section ---------- ------ -------- MISSING_SESSION_ID TBD 4 CANNOT_ALLOC_IP TBD 5 8. IANA Considerations The Session Identifier Extension defined in Section 2 is a Mobile IP registration extension as defined in RFC 2002 [3]. IANA should assign a Type value consistent with this number space. McCann and Leung Expires 09/2000 5 INTERNET DRAFT Mobile IP Session ID Extension March 2000 The Code values defined in Section 6 are error codes as defined in RFC 2002 [3]. IANA should assign values to these codes consistent with this number space. 9. Security Considerations Mobile IP registration messages are authenticated, and the authentication verified by the recipient. The Session Identifier Extension is always covered by at least a Mobile-Home Authentication Extension. 10. IPv6 Considerations As with the NAI extension for Mobile IP [1], support for Session ID based registration in IPv6 is outside the scope of this document. Any of the methods suggested there for creating an attendant function in the visited network could also make use of a Session ID extension to support multiple, simultaneous sessions. 11. Acknowledgements Thanks to Mohamed Khalil for his participation in early drafts of this document. 12. Intellectual Property Statement Cisco may have IPR on material contained in this draft. Upon approval by the IESG of the relevant Internet standards track specification and if any patents issue to Cisco or its subsidiaries with claims that are necessary for practicing this standard, any party will be able to obtain the right to implement, use and distribute the technology or works when implementing, using or distributing technology based upon the specific specification(s) under openly specified, reasonable, non-discriminatory terms. 13. References [1] P. Calhoun and C. Perkins. Mobile IP Network Access Identifier Extension. Internet Draft, Internet Engineering Task Force. draft-ietf-mobileip-mn-nai-07.txt, January 2000. Work in progress. [2] B. Aboba and M. Beadles. The Network Access Identifier. Request for Comments (Proposed Standard) 2486, Internet Engineering Task Force, January 1999 McCann and Leung Expires 09/2000 6 INTERNET DRAFT Mobile IP Session ID Extension March 2000 [3] C. Perkins. IP Mobility Support for IPv4, revised. Internet Draft, Internet Engineering Task Force. draft-ietf-mobileip-rfc2002-bis-01.txt, January 2000. Work in progress. Author's Addresses Questions about this memo can be directed to: Peter J. McCann Lucent Technologies Rm 2Z-305 263 Shuman Blvd Naperville, IL 60566 USA email: mccap@lucent.com phone: +1 630 713 9359 fax: +1 630 713 4982 Kent Leung Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA 95134 USA email: kleung@cisco.com phone: +1 408 526 5030 fax: +1 408 526 4952 McCann and Leung Expires 09/2000 7