Internet DRAFT - draft-haas-idr-flowspec-redirect-rt-bis
draft-haas-idr-flowspec-redirect-rt-bis
Internet Engineering Task Force J. Haas, Ed.
Internet-Draft Juniper Networks
Updates: 5575 (if approved) February 5, 2014
Intended status: Standards Track
Expires: August 9, 2014
Clarification of the Flowspec Redirect Extended Community
draft-haas-idr-flowspec-redirect-rt-bis-01
Abstract
This document clarifies the formatting of the the BGP Flowspec
Redirect Extended Community, originally documented in RFC 5575.
Status of this Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
5. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Introduction
Dissemination of Flow Specification Rules [RFC5575], commonly known
as BGP Flowspec, provided for a BGP Extended Community [RFC4360] that
served to redirect traffic to a VRF routing instance that matched the
flow specification NLRI. In that RFC, the Redirect Extended
Community was documented as follows:
: +--------+--------------------+--------------------------+
: | type | extended community | encoding |
: +--------+--------------------+--------------------------+
: | 0x8008 | redirect | 6-byte Route Target |
: +--------+--------------------+--------------------------+
:
: [...]
:
: Redirect: The redirect extended community allows the traffic to be
: redirected to a VRF routing instance that lists the specified
: route-target in its import policy. If several local instances
: match this criteria, the choice between them is a local matter
: (for example, the instance with the lowest Route Distinguisher
: value can be elected). This extended community uses the same
: encoding as the Route Target extended community [RFC4360].
: [...]
:
: 11. IANA Considerations
: [...]
:
: The following traffic filtering flow specification rules have been
: allocated by IANA from the "BGP Extended Communities Type -
: Experimental Use" registry as follows:
: [...]
:
: 0x8008 - Flow spec redirect
The IANA registry of BGP Extended Communities clearly identifies
communities of specific formats. For example, "Two-octet AS Specific
Extended Community" [RFC4360], "Four-octet AS Specific Extended
Community" [RFC5668] and "IPv4 Address Specific Extended Community"
[RFC4360]. Route Targets [RFC4360] identify this format in the high-
order (Type) octet of the Extended Community and set the value of the
low-order (Sub-Type) octet to 0x02. The Value field of the Route
Target Extended Community is intended to be interpreted in the
context of its format.
Since the Redirect Extended Community only registered a single code-
point in the IANA BGP Extended Community registry, a common
interpretation of the Redirect Extended Community's "6-byte Route
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Target" has been to look for any matching Route Target sharing the
same Value portion of its Extended Community. Thus, multiple Route
Targets provisioned in a router's VRFs might match even though the
format was different.
This "Value wildcard" behavior does not matched deployed
implementations of BGP Flowspec. Deployed implementations of BGP
Flowspec use the following formatting for the Redirect Extended
Community:
+--------+--------------------+-------------------------------------+
| type | extended community | encoding |
+--------+--------------------+-------------------------------------+
| 0x8008 | redirect AS-2byte | 2-octet AS, 4-octet Value |
| 0x8108 | redirect IPv4 | 4-octet IPv4 Address, 2-octet Value |
| 0x8208 | redirect AS-4byte | 4-octet AS, 2-octet Value |
+--------+--------------------+-------------------------------------+
It should be noted that the low-order nybble of the Redirect's Type
field corresponds to the Route Target Extended Community format field
(Type). (See [RFC4360], Secs. 3.1, 3.2 and [RFC5668], Sec. 2.) The
low order octet (Sub-Type) of the Redirect Extended Community remains
0x08, contrasted to 0x02 for Route Targets.
The IANA Registries for BGP Extended Communities
[I-D.ietf-idr-extcomm-iana] document was written to update the
previously-mentioned IANA registries to better document BGP Extended
Community formats. The IANA Considerations section below further
amends those registry updates in order to properly document the
flowspec redirect communities.
2. IANA Considerations
IANA is requested to update the BGP GENERIC TRANSITIVE EXPERIMENTAL
USE EXTENDED COMMUNITY SUB-TYPES registry as follows:
0x08 - Flow spec redirect AS-2byte format.
IANA is requested to update the BGP TRANSITIVE EXTENDED COMMUNITY
TYPES registry as follows:
0x81 - Generic Transitive Experimental Extended Community
Part 2 (Sub-Types are defined in the "Generic Transitive
Experimental Extended Community Part 2 Sub-Types" Registry)
0x82 - Generic Transitive Experimental Extended Community
Part 3 (Sub-Types are defined in the "Generic Transitive
Experimental Extended Community Part 3 Sub-Types" Registry)
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IANA is requested to create the GENERIC TRANSITIVE EXPERIMENTAL
EXTENDED COMMUNITY PART 2 SUB-TYPES registry. It should be seeded
with the following Sub-Type:
0x08 - Flow spec redirect IPv4 format.
IANA is requested to create the GENERIC TRANSITIVE EXPERIMENTAL
EXTENDED COMMUNITY PART 3 SUB-TYPES registry. It should be seeded
with the following Sub-Type:
0x08 - Flow spec redirect AS-4byte format.
3. Security Considerations
This document introduces no additional security considerations than
those already covered in [RFC5575].
4. Acknowledgements
The contents of this document was raised as part of implementation
discussions of BGP Flowspec with the following individuals:
Andrew Karch (Cisco)
Robert Raszuk (NTT I3)
Adam Simpson (Alcatel-Lucent)
Matthieu Texier (Arbor Networks)
Kaliraj Vairavakkalai (Juniper)
5. Normative References
[I-D.ietf-idr-extcomm-iana]
Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", draft-ietf-idr-extcomm-iana-02
(work in progress), December 2013.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
[RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J.,
and D. McPherson, "Dissemination of Flow Specification
Rules", RFC 5575, August 2009.
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[RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS
Specific BGP Extended Community", RFC 5668, October 2009.
Author's Address
Jeffrey Haas (editor)
Juniper Networks
1194 N. Mathida Ave.
Sunnyvale, CA 94089
US
Email: jhaas@juniper.net
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