Internet DRAFT - draft-retana-idr-aigp-cost-community
draft-retana-idr-aigp-cost-community
Network Working Group A. Retana
Internet-Draft A. Kapoor
Intended status: Informational K. Patel
Expires: April 27, 2015 Cisco Systems, Inc.
October 24, 2014
Use of the Cost Community to carry the Accumulated IGP Metric
draft-retana-idr-aigp-cost-community-01
Abstract
This document explains the use of the Cost Community to flexibly
carry the Accumulated IGP Metric.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
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This Internet-Draft will expire on April 27, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. Use of the Cost Community to carry the AIGP . . . . . . . . . 2
4. Security Considerations . . . . . . . . . . . . . . . . . . . 3
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 3
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 3
7.1. Normative References . . . . . . . . . . . . . . . . . . 3
7.2. Informative References . . . . . . . . . . . . . . . . . 3
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 3
1. Introduction
The Accumulated IGP Metric (AIGP) Attribute [RFC7311] has been
defined with the purpose of carrying an AIGP. The attribute is used
in the BGP selection process before the tie braking procedures
[RFC4271], effectively after the LOCAL_PREF comparison.
The Cost Community [I-D.ietf-idr-custom-decision] can provide a
flexible mechanism to carry the AIGP. It can se used both at a
different point in the selection process, or as a direct replacement
for the AIGP attribute in networks that don't fully support it.
2. Requirements Language
The key words "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].
3. Use of the Cost Community to carry the AIGP
The applicability and procedures defined in [RFC7311] for originating
and modifying the AIGP value are not changed in this document. The
value is used as the Cost of the Cost Community.
The Point of Insertion (POI) can be set to any of the values defined
in [I-D.ietf-idr-custom-decision]. Note that the use of the
LOCAL_PREF POI is equivalent to using the AIGP Attribute in routers
that don't support it.
If the Cost Community is used to carry the AIGP value, then the AIGP
Attribute SHOULD NOT be used. If used, then the high-order bit of
the Community-ID MUST be set in a Cost Community with a POI of AIGP
to avoid an inconsistent selection process. Note that this operation
doesn't preclude using a Cost Community with a Cost of the AIGP at a
different POI.
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4. Security Considerations
This document explains the use of the Cost Community to provide
flexibility in the application of routing policy related to the
accumulated IGP metric of a route. As such, it does not introduce
new security risks than the ones considered in
[I-D.ietf-idr-custom-decision] or [RFC7311].
5. IANA Considerations
This document has no IANA actions.
6. Acknowledgements
TBD
7. References
7.1. Normative References
[I-D.ietf-idr-custom-decision]
Retana, A. and R. White, "BGP Custom Decision Process",
draft-ietf-idr-custom-decision-05 (work in progress),
October 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC7311] Mohapatra, P., Fernando, R., Rosen, E., and J. Uttaro,
"The Accumulated IGP Metric Attribute for BGP", RFC 7311,
August 2014.
7.2. Informative References
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006.
Authors' Addresses
Alvaro Retana
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
USA
Email: aretana@cisco.com
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Anoop Kapoor
Cisco Systems, Inc.
170 Tasman Drive
San Jose, CA 95134
USA
Email: ankapoor@cisco.com
Keyur Patel
Cisco Systems, Inc.
170 Tasman Drive
San Jose, CA 95134
USA
Email: keyupate@cisco.com
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