One document matched: draft-ietf-mobileip-nai-wn-00.txt-11638.txt
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.
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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
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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.
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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:
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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.
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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.
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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
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