Internet Engineering Task Force Lachu Aravamudhan INTERNET-DRAFT Mark R. O`Brien <draft-ietf-mobileip-nai-wn-00.txt> Basavaraj Patil Date: February 1999 Nortel Networks Expires: July 1999 NAI Resolution for Wireless Networks Status of this memo 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 RFC 2468 [1] defines the need of a standardized format for identifying ISP subscribers for dial-up roaming operations. It introduced the Network Access Identifier (NAI) to fulfill this need. The NAI is provided by the mobile node to the dialed ISP during PPP authentication. The ability to resolve an NAI for second and third generation cellular mobile nodes allow traditional cellular service providers to evolve their home cellular networks to provide cellular services, IP packet data services and so on with a single subscription using NAIs. Additionally, this allows cellular provider to evolve their networks to be IP based. Second and third generation cellular mobile nodes must perform a registration and authentication process with their wireless service provider before the mobile node user may initiate other operations (See [1] for examples). These mobile nodes do not support the programming of an NAI nor does the cellular registration message support the transfer of an NAI to the wireless access network. For example, North American cellular networks (e.g. AMPS, TDMA, CDMA) service mobile nodes that register with a Mobile Identification Number (MIN). The MIN is then associated with a cellular subscriber. For the same reasons stated in [1], it would be convenient if an option was available to provide the wireless subscriber identification in the form of an NAI during the wireless registration and authentication process. This draft proposes a solution to resolve NAIs from traditional mobile node identifiers. 1. Introduction RFC 2468 [1] defines the need of a standardized format for identifying ISP subscribers for dial-up roaming operations. It introduced the Network Access Identifier (NAI) to fulfill this need. The NAI is provided by the mobile node to the dialed ISP during PPP authentication. The ability to resolve an NAI for second and third generation cellular mobile nodes allow traditional cellular service providers to evolve their home cellular networks to provide cellular services, IP packet data services and so on with a single subscription using NAIs. Additionally, this allows cellular provider to evolve their networks to be IP based. Second and third generation cellular mobile nodes must perform a registration and authentication process with their wireless service provider before the mobile node user may initiate other operations (See [1] for examples). These mobile nodes do not support the programming of an NAI nor does the cellular registration message support the transfer of an NAI to the wireless access network. For example, North American cellular networks (e.g. AMPS, TDMA, CDMA) service mobile nodes that register with a Mobile Identification Number (MIN). The MIN is then associated with a cellular subscriber. For the same reasons stated in [1], it would be convenient if an option was available to provide the wireless subscriber identification in the form of an NAI during the wireless registration and authentication process. This draft proposes a solution to resolve NAIs from traditional mobile node identifiers. Aravamudhan, O`Brien Expires July 1999 [Page 2]
Internet-Draft NAI Resolution for Wireless Networks February 1999 Consider the following scenario to illustrate the NAI resolution required to register and authenticate wireless mobile nodes with their wireless service provider: NAI enabled Wireless Service Provider owns the cellular service for Subscriber A (SUB A). ------------ ------------ ---------------- | SUB A | | | | | | Cellular | | Wireless | | NAI Enabled | | Mobile | | Access | | Wireless Home| | Node | | Network | | Network | ------------ ------------ ---------------- | | | event |)))))))))))))>| | a | |-------------->| b | |<--------------| c |<(((((((((((((| | d | | | a SUB A powers-on his second or third generation cellular mobile node. The act of powering on causes the cellular mobile mode to attempt a wireless registration. The registration message identifies the mobile node by its MIN. b The wireless access network receives the wireless registration message and resolves an NAI based on the MIN sent by the cellular mobile node. The wireless access network sends an appropriate registration message to its NAI enabled home network. c The NAI enabled home network registers and authenticates wireless SUB A and sends an appropriate registration response back to the wireless access network. d The wireless access network receives the registration response from its home network and sends an appropriate wireless registration return result to SUB A`s cellular mobile node. 2. Terminology This document uses the following terminology: Aravamudhan, O`Brien Expires July 1999 [Page 3]
Internet-Draft NAI Resolution for Wireless Networks February 1999 MIN Mobile Identification Number: A 10-digit number assigned to the mobile station. 3. Specification Language The keywords "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 [2]. 4. NAI Resolution There are many alternatives to resolve an NAI. The intent of defining this draft is to stimulate discussion on the merits of resolving NAIs from second and third generation wireless mobile nodes. One method is presented herein. The NAI is of the form user@realm. At the wireless access provider, using the wireless registration information, a temporary NAI may be constructed of the form <MIN>@realm. The IP address corresponding to the realm may then be resolved through DNS or other appropriate mechanisms. That resolution should return the IP address of the realm (i.e. the Service Provider owning the subscriber's wireless service). The temporary NAI, <MIN>@realm, should then be supplied in the registration message to the wireless service provider identified by that IP address. The wireless service provider should receive the registration message and may decode the "user" component of the temporary NAI to lookup the subscriber's NAI if it is, in fact, different from the temporary NAI. For example, suppose a cellular mobile node sends a registration message to the wireless access network with a MIN of 9726841000. A table resident at wireless access network may be populated with a range of MINs covered by each entry. In this example, each range specifies only the most significant 6 digits and implicitly includes all subscriber numbers (last 4 digits) within the range: MIN RANGE REALM 214790 - 214799 abc_company.net 972680 - 972689 def_company.net 972700 - 972730 hij_company.net In this case "def_company.net" is the ISP for the 9726841000 MIN. The resulting temporary NAI to use for IP address resolution and for routing of registration messages over the Internet would be: 9726841000@def_company.net. Aravamudhan, O`Brien Expires July 1999 [Page 4]
Internet-Draft NAI Resolution for Wireless Networks February 1999 Table lookups such as these have been widely used in cellular networks since the subscriber/terminal identifiers are: numeric, a maximum of 15 digits, and the leading digits typically defined a geographical region to facilitate routing. Further, ranges of subscriber/terminal identifications were assigned in blocks to service providers in each regions. As shown in the table, def_company.net is assigned all of the subscriber numbers from exchanges 680 though 689 inclusive. This facilitated scalability by alleviating access providers from a requirement of enumerating each MIN in their tables. NOTE: The interface from the wireless access network to the wireless service provider network should use protocols produced by the IETF and is outside of the scope of this document. With the exception of the derivation of an NAI from a MIN, the means by which a cellular registration or authentication message is converted by the wireless access network to the relevant IETF protocol message(s) is outside the scope of this document. Aravamudhan, O`Brien Expires July 1999 [Page 5]
Internet-Draft NAI Resolution for Wireless Networks February 1999 5. References [1] Aboba B., Beadles M., "Network Access Identifier" RFC 2486, January 1999. [2] Bradner S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997. 6. Acknowledgments The authors would like to thank Emad Qaddoura, Scott Skraboly, Russ Coffin and Rambabu Tummala of Nortel Networks for their review and valuable input. 7. Authors' Addresses Lachu Aravamudhan Nortel Networks Inc. 2201 Lakeside Blvd. Richardson, TX. 75082-4399 Phone: 972-684-4855 email: lachu@nortelnetworks.com Mark O'Brien Nortel Networks Inc. 2201 Lakeside Blvd. Richardson, TX. 75082-4399 Phone: 972-684-5164 email: markob@nortelnetworks.com Aravamudhan, O`Brien Expires July 1999 [Page 6]
