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Inter-Domain RoutingP. Jakma
Internet-DraftDCS, Uni. of Glasgow
Updates: rfc4271October 12, 2010
(if approved) 
Intended status: Standards Track 
Expires: April 15, 2011 


Revisions to the BGP 'Minimum Route Advertisement Interval'
draft-ietf-idr-mrai-dep-03

Abstract

This document revises the specification of the BGP MRAI timer, by deprecating the previously recommended values and by allowing for withdrawals to be exempted from the MRAI.

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/.

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This Internet-Draft will expire on April 15, 2011.

Copyright Notice

Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved.

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Table of Contents

1.  Requirements Language
2.  Background
3.  Revision
4.  IANA Considerations
5.  Security Considerations
6.  Normative References
§  Author's Address




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1.  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] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).



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2.  Background

The Minimum Route Advertisement Interval (MRAI) timer is specified in [RFC4271] (Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” January 2006.). This timer acts to rate-limit updates, on a per-destination basis. [RFC4271] (Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” January 2006.) suggests values of 30s and 5s for this interval for eBGP and iBGP respectively. The MRAI must also be applied to withdrawals according to RFC4271, a change from the earlier [RFC1771] (Rekhter, Y. and T. Li, “A Border Gateway Protocol 4 (BGP-4),” March 1995.).

The MRAI timer has a significant effect on the convergence of BGP, in terms of convergence time, the number of messages, amongst other metrics. The optimum value for this timer is hard to estimate, never mind calculate and will differ between networks, and probably even different subsets of the same network.



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3.  Revision

The suggested default values for the MinRouteAdvertisementIntervalTimer given in [RFC4271] (Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” January 2006.) are deprecated. The appropriate choice of default values is left to the discretion of implementors. Implementations SHOULD provide a means to allow operators to choose values appropriate to their requirements, on a per-peer and per-AFI/SAFI basis. Implementations MAY exempt withdrawals from the MRAI timer.



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4.  IANA Considerations

There are no requests made to IANA in this document.



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5.  Security Considerations

This document raises no new security considerations.



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6. Normative References

[RFC1771] Rekhter, Y. and T. Li, “A Border Gateway Protocol 4 (BGP-4),” RFC 1771, March 1995 (TXT).
[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” BCP 14, RFC 2119, March 1997 (TXT, HTML, XML).
[RFC4271] Rekhter, Y., Li, T., and S. Hares, “A Border Gateway Protocol 4 (BGP-4),” RFC 4271, January 2006 (TXT).


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Author's Address

  Paul Jakma
  School of Computing Science, Uni. of Glasgow
  Sir Alwyn Williams Building
  University of Glasgow
  Glasgow G12 8QQ
  UK
Email:  paulj@dcs.gla.ac.uk