ROAMOPS Working Group Bernard Aboba
INTERNET-DRAFT Microsoft
Category: Updates RFC 2138
<draft-ietf-roamops-mobileip-00.txt>
9 March 1998
Support for Mobile IP in Roaming
1. Status of this Memo
This document is an Internet-Draft. Internet-Drafts are working docu-
ments of the Internet Engineering Task Force (IETF), its areas, and
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The distribution of this memo is unlimited. It is filed as <draft-
ietf-roamops-mobileip-00.txt>, and expires September 1, 1998. Please
send comments to the authors.
2. Abstract
This document describes how Mobile IP may be supported in roaming, via
definition of a RADIUS attribute for Mobile-IP v4 Configuration
Option, as described in RFC 2290.
3. Introduction
As described in [6], support for Mobile IP is a requirement for a
roaming standard.
RFC 2290 [8] describes the Mobile-IPv4 Configuration Option for PPP
IPCP. This option allows two PPP peers to communicate their support
for Mobile IP, as well as for the NAS to pass the home address to the
dial-in user.
In order to permit Mobile IP configuration in roaming services, this
document defines modifications to the RADIUS Framed-IP-Address
Attribute, as well as defining a new Mobile-IP-Configuration
attribute.
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4. Attribute definitions
4.1. Framed-IP-Address
Description
This Attribute indicates the address to be configured for the user.
It MAY be used in Access-Accept packets. It MAY be used in an
Access-Request packet as a hint by the NAS to the server that it
would prefer that address, but the server is not required to honor
the hint.
A summary of the Framed-IP-Address Attribute format is shown below.
The fields are transmitted from left to right.
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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
8 for Framed-IP-Address
Length
6
Address
The Address field is four octets. The value 0xFFFFFFFF indicates
that the NAS should allow the user to select an address (e.g.
Negotiated). The value 0xFFFFFFFE indicates that the NAS should
select an address for the user (e.g. Assigned from a pool of
addresses kept by the NAS). The value 0xFFFFFFFD indicates that
Mobile IP will be configured for the user, and therefore that the
NAS should not select an address for the user, Other valid values
indicate that the NAS should use that value as the user's IP
address.
4.2. Mobile-IP-Configuration
Description
This Attribute indicates the Mobile-IP Home Address to be config-
ured for the user. It MAY be used in Access-Accept packets.
A summary of the Mobile-IP-Configuration Attribute format is shown
below. The fields are transmitted from left to right.
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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 2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Address
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address (cont) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
? for Mobile-IP-Configuration
Length
6
Address
The Address field is four octets, and encodes the Mobile Node's
Home Address. This field MUST NOT be zero.
5. Acknowledgements
Thanks to Glen Zorn of Microsoft for useful discussions of this prob-
lem space.
6. References
[1] B. Aboba, J. Lu, J. Alsop, J. Ding, W. Wang. "Review of Roaming
Implementations." RFC 2194, Microsoft, Aimnet, i-Pass Alliance, Asi-
ainfo, Merit, September 1997.
[2] C. Rigney, A. Rubens, W. Simpson, S. Willens. "Remote Authenti-
cation Dial In User Service (RADIUS)." RFC 2138, Livingston, Merit,
Daydreamer, April 1997.
[3] C. Rigney. "RADIUS Accounting." RFC 2139, Livingston, April
1997.
[4] S. Bradner. "Key words for use in RFCs to Indicate Requirement
Levels." RFC 2119, Harvard University, March, 1997.
[5] C. Rigney, W. Willats. "RADIUS Extensions." Internet draft (work
in progress), draft-ietf-radius-ext-01.txt, Livingston, December 1997.
[6] B. Aboba, G. Zorn. "Roaming Requirements," Internet draft (work
in progress), draft-ietf-roamops-roamreq-07.txt, Microsoft, March
1998.
[7] C. Perkins. "IP Mobility Support." RFC 2002, IBM October 1996.
[8] J. Solomon, S. Glass, "Mobile-IPv4 Configuration Option for PPP
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IPCP." RFC 2290, Motorola, FTP Software, February 1998.
7. Authors' Addresses
Bernard Aboba
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
Phone: 425-936-6605
EMail: bernarda@microsoft.com
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