Network Working Group P. Yegani
Internet-Draft Juniper Networks
Intended status: Standards Track K. Leung
Expires: December 3, 2010 Cisco Systems
A. Lior
Bridgewater Systems
K. Chowdhury
J. Navali
Cisco Systems
June 1, 2010
GRE Key Extension for Mobile IPv4
draft-ietf-mip4-gre-key-extension-00.txt
Abstract
The GRE specification contains a Key field, which MAY contain a value
that is used to identify a particular GRE data stream. This
specification defines a new Mobile IP extension that is used to
exchange the value to be used in the GRE Key field. This extension
further allows the Mobility Agents to setup the necessary protocol
interfaces prior to receiving the mobile's traffic. The new
extension option allows a foreign agent to request GRE tunneling
without disturbing the Home Agent behavior specified for Mobile Ipv4.
GRE tunneling provides an advantage that allows operator's private
home networks to be overlaid and allows the HA to provide overlapping
home addresses to different subscribers. When the tuple < Care of
Address, Home Address and Home Agent Address > is the same across
multiple subscriber sessions, GRE tunneling will provide a means for
the FA and HA to identify data streams for the individual sessions
based on the GRE key. In the absence of this key identifier, the
data streams cannot be distinguished from each other, a significant
drawback when using IP-in-IP tunneling.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 3, 2010.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. GRE-Key Extension . . . . . . . . . . . . . . . . . . . . . . . 4
4. Operation and Use of the GRE-Key Extension . . . . . . . . . . 4
4.1. Foreign Agent Requirements for GRE Tunneling Support . . . 4
4.2. Home Agent Requirements for GRE Tunneling Support . . . . . 5
4.3. Mobile Node Requirements for GRE Tunneling Support . . . . 6
5. GRE Key Extension and Tunneling Procedures . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. Normative references . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
This document specifies a new extension for use by Foreign Agents
operating Mobile IP for IPv4. The new extension option allows a
foreign agent to request GRE tunneling without disturbing the Home
Agent behavior specified for Mobile IPv4 [RFC3344]. This extension
contains the GRE key and other necessary information required for
establishing a GRE tunnel between the FA and the HA.
GRE tunneling provides an advantage that allows operator's private
home networks to be overlaid and it allows the HA to provide
overlapping home addresses to different subscribers. When the tuple
< Care of Address, Home Address and Home Agent Address > is the same
across multiple subscriber sessions, GRE tunneling will provide a
means for the FA and the HA to identify data streams for the
individual sessions based on the GRE key. In the absence of this key
identifier, the data streams cannot be distinguished from each other,
a significant drawback when using IP-in-IP tunneling.
2. Terminology
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 [RFC2119]. Other
terminology is used as already defined in [RFC3344].
3. GRE-Key Extension
The format of the GRE-Key Extension conforms to the Extension format
specified for Mobile IPv4 [RFC3344]. This extension option is used
by the Foreign Agent to supply GRE key and other necessary
information to the Home Agent to establish a GRE tunnel between the
FA and the HA.
4. Operation and Use of the GRE-Key Extension
4.1. Foreign Agent Requirements for GRE Tunneling Support
The FA MUST support IP-in-IP tunneling of datagrams for Mobile IPv4
[RFC3344]. The FA may support GRE tunneling that can be used, for
example, to allow for overlapping private home IP addresses
[X.S0011-D]. If the FA is capable of supporting GRE encapsulation,
it should set the 'G' bit in the Flags field in the Agent
Advertisement message sent to the MN during the Mobile IP session
establishment.
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If the MN does not set the 'G' bit, the FA MAY fall back to using IP-
in-IP encapsulation for the session per [RFC3344].
If the MN does not set the 'G' bit, and the local policy allows the
FA to override the 'G' bit setting received from the MS, the FA MUST
include the GRE-Key Extension as defined in this memo in the
Registration Request message to request GRE encapsulation for the
session.
If the FA does not support GRE encapsulation, the FA MUST reset the
'G' bit in the Agent Advertisement message. In this case, if the MN
sets the 'G' bit in the Registration Request message, the FA returns
a Registration Reply message to the MN with code 'Requested
Encapsulation Unavailable' (0x48) per [RFC3344].
If the FA allows GRE encapsulation, and either the MN requested GRE
encapsulation or local policy dictates using GRE encapsulation for
the session, the FA MUST include the GRE Key in the GRE Key Extension
in all Mobile IP Registration Requests (including initial, renewal
and de-registration requests) before forwarding the request to the
HA. The FA may include a GRE key of value zero in the GRE Key
Extension to signal that the HA assign GRE keys in both directions.
The GRE key assignment in the FA and the HA is outside the scope of
this memo.
The GRE Key Extension SHALL follow the format defined in [RFC3344].
This extension SHALL be added after the MN-HA and MN-FA Challenge and
MN-AAA extensions (if any) and before the FA-HA Auth extension (if
any).
4.2. Home Agent Requirements for GRE Tunneling Support
The HA MUST follow the procedures specified in RFC 3344 in processing
this extension in Registration Request messages. If the HA receives
the GRE Key Extension in a Registration Request and does not
recognize GRE Key Extension, it MUST send an RRP with code 'Unknown
Extension (0xY1)' per [RFC3344].
If the HA receives the GRE Key Extension in a Registration Request
and recognizes the GRE Key Extension but is not configured to support
GRE encapsulation, it MUST send an RRP with code 'Requested
Encapsulati on Unavailable (0xYY)'.
If the HA receives a Registration Request with a GRE Key Extension
but without the 'G' bit set, the HA SHOULD treat this as if 'G' bit
is set in the Registration Request i.e., the presence of GRE Key
Extension indicates a request for GRE encapsulation.
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If the HA receives the GRE Key Extension in a Registration Request
and recognizes the GRE Key Extension as well as supports GRE
encapsulation, the following procedures should apply:
The HA SHOULD accept the RRQ and send a RRP with code 'Accepted (0)'.
The HA MUST assign a GRE key and include the GRE Key Extension in the
RRP before sending it to the FA. The HA MUST include the GRE Key
Extension in all RRPs in response to any RRQ that included GRE Key
Extension, when a GRE key is available for the registration.
If the HA receives the GRE Key Extension in the initial Registration
Request and recognizes the GRE Key Extension carrying a GRE key value
of zero, it SHOULD accept the RRQ and send a RRP with code 'Accepted
(0)'. The HA MUST assign GRE keys for both directions and include
these keys in the GRE Key Extension in the RRP before sending it to
the FA. The HA MUST include the GRE Key Extension in the RRP in
response to the initial RRQ that included GRE Key Extension, when a
GRE key is available for the registration.
4.3. Mobile Node Requirements for GRE Tunneling Support
If the MN is capable of supporting GRE encapsulation, it SHOULD set
the 'G' bit in the Flags field in the Registration Request per
[RFC3344].
5. GRE Key Extension and Tunneling Procedures
GRE tunneling support for Mobile IP will permit asymmetric GRE keying
i.e., the FA assigns a GRE key for use in encapsulated traffic and
the HA can assign its own GRE key. Once the GRE keys have been
exchanged, the FA uses the HA-assigned key in the encapsulating GRE
header for reverse tunneling and the HA uses the FA-assigned key in
the encapsulating GRE header.
The format of the GRE Key Extension is as shown below.
The GRE Key extension MAY be included in Registration Requests
[RFC3344], whose 'G' bit is enabled. The GRE Key extension is used
to inform the recipient of the Mobile IP request of the value to be
used in GRE's Key field.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
TBD (non-skippable) [2]
Length
6
Reserved
This field MUST be set to zero (0).
Key Identifier
This is a four octet value assigned in the Registration and
inserted in every GRE frame.
Figure 1: GRE Key Extension
6. IANA Considerations
The GRE Key extension defined in this memo is as defined in
[RFC3344]. IANA should assign a value for this Extension.
7. Security Considerations
This specification does not introduce any new security
considerations, beyond those described in [RFC3344]
8. Acknowledgements
Thanks to Jun Wang, Gopal Dommety and Sri Gundavelli for their
helpful comments, offline discussions and reviewing the initial
draft.
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9. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2890] Dommety, G., "Key and Sequence Number Extensions to GRE",
RFC 2890, September 2000.
[RFC3344] Perkins, C., "IP Mobility Support for IPv4", RFC 3344,
August 2002.
Authors' Addresses
Parviz Yegani
Juniper Netowrks
1194 North Mathilda Ave.
Sunnyvale, California 94089
U.S.A
Phone: +1 408-759-1973
Email: pyegani@juniper.net
Kent Leung
Cisco Systems Incorporated
170 West Tasman Drive
San Jose, California 95134
U.S.A
Phone: +1 408 526 5030
Email: kleung@cisco.com
Avi Lior
Bridgewater Systems Corporation
303 Terry Fox Drive
Ottawa, Ontario K2K 3J1
Canada
Phone: +1 613-591-6655
Email: avi@bridgewatersystems.com
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Kuntal Chowdhury
Cisco Systems Incorporated
170 West Tasman Drive
San Jose, California 95134
U.S.A
Email: kchowdhu@cisco.com
Jay Navali
Cisco Systems Incorporated
170 West Tasman Drive
San Jose, California 95134
U.S.A
Email: jnavali@cisco.com
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