Internet DRAFT - draft-ietf-idr-flowspec-redirect-rt-bis
draft-ietf-idr-flowspec-redirect-rt-bis
Internet Engineering Task Force J. Haas, Ed.
Internet-Draft Juniper Networks
Updates: 5575 (if approved) July 27, 2015
Intended status: Standards Track
Expires: January 28, 2016
Clarification of the Flowspec Redirect Extended Community
draft-ietf-idr-flowspec-redirect-rt-bis-05
Abstract
This document updates RFC 5575 (Dissemination of Flow Specification
Rules) to clarify the formatting of the the BGP Flowspec Redirect
Extended Community.
Status of This Memo
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This Internet-Draft will expire on January 28, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
2.1. BGP Transitive Extended Community Types . . . . . . . . . 4
2.2. Update to BGP Generic Transitive Experimental Use
Extended Community Sub-Types . . . . . . . . . . . . . . 5
2.3. Generic Transitive Experimental Extended Community Part 2
Sub-Types . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Generic Transitive Experimental Extended Community Part 3
Sub-Types . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
5. Normative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
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:
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: +--------+--------------------+--------------------------+
: | 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
target" has been to look, at a receiving router, for a route target
value that matches the route target value in the received redirect
extended community, and import the advertised route to the
corresponding VRF instance subject to the rules defined in [RFC5575].
However, because the route target format in the redirect extended
community is not clearly defined, the wrong match may occur.
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This "value wildcard" matching behavior, which does not take into
account the format of the route target defined for a local VRF and
may result in the wrong matching decision, does not match deployed
implementations of BGP Flowspec. Deployed implementations of BGP
Flowspec solve this problem by defining different redirect extended
communities that are specific to the format of the route target
value. This document defines the following redirect extended
communities:
+--------+--------------------+-------------------------------------+
| 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 nibble of the Redirect's Type
field corresponds to the Route Target Extended Community format field
(Type). (See [RFC4360], Secs. 3.1, 3.2, and 4 plus [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 [RFC7153] 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
2.1. BGP Transitive Extended Community Types
IANA is requested to update the "BGP Transitive Extended Community
Types" registry as follows:
0x81 - Generic Transitive Experimental Use Extended Community
Part 2 (Sub-Types are defined in the "Generic Transitive
Experimental Extended Community Part 2 Sub-Types" Registry)
0x82 - Generic Transitive Experimental Use Extended Community
Part 3 (Sub-Types are defined in the "Generic Transitive
Experimental Extended Community Part 3 Sub-Types" Registry)
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2.2. Update to BGP Generic Transitive Experimental Use Extended
Community Sub-Types
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. [RFC5575, RFC-to-be]
(Note to RFC Editor - replace RFC-to-be with this RFC number.)
2.3. Generic Transitive Experimental Extended Community Part 2 Sub-
Types
IANA is requested to create the "Generic Transitive Experimental Use
Extended Community Part 2 Sub-Types" registry. This registry should
be created under the BGP Extended Communities registry. It will
contain the following note:
This registry contains values of the second octet (the "Sub-Type"
field) of an extended community when the value of the first octet
(the "Type" field) is 0x81.
Registry Name: Generic Transitive Experimental Use Extended Community
Part 2 Sub-Types
RANGE REGISTRATION PROCEDURE REFERENCE
0x00-0xBF First Come First Served
0xC0-0xFF IETF Review
SUB-TYPE VALUE NAME
0x00-0x07 Unassigned
0x08 Flow spec redirect IPv4 format. [RFC-to-be]
0x09-0xff Unassigned
(Note to RFC Editor - replace RFC-to-be with this RFC number.)
2.4. Generic Transitive Experimental Extended Community Part 3 Sub-
Types
IANA is requested to create the "Generic Transitive Experimental Use
Extended Community Part 3 Sub-Types" registry. This registry should
be created under the BGP Extended Communities registry. It will
contain the following note:
This registry contains values of the second octet (the "Sub-Type"
field) of an extended community when the value of the first octet
(the "Type" field) is 0x82.
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Registry Name: Generic Transitive Experimental Use Extended Community
Part 2 Sub-Types
RANGE REGISTRATION PROCEDURE REFERENCE
0x00-0xBF First Come First Served
0xC0-0xFF IETF Review
SUB-TYPE VALUE NAME
0x00-0x07 Unassigned
0x08 Flow spec redirect AS-4byte format. [RFC-to-be]
0x09-0xff Unassigned
(Note to RFC Editor - replace RFC-to-be with this RFC number.)
3. Security Considerations
This document introduces no additional security considerations than
those already covered in [RFC5575]. It should be noted that if the
wildcard behavior were actually implemented, this ambiguity may lead
to the installation of Flowspec rules in an incorrect VRF and may
lead to traffic to be incorrectly delivered.
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
Adam Simpson (Alcatel-Lucent)
Matthieu Texier (Arbor Networks)
Kaliraj Vairavakkalai (Juniper)
5. Normative References
[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.
[RFC7153] Rosen, E. and Y. Rekhter, "IANA Registries for BGP
Extended Communities", RFC 7153, March 2014.
Author's Address
Jeffrey Haas (editor)
Juniper Networks
Email: jhaas@juniper.net
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