Inter-Domain Routing                                            P. Jakma
Internet-Draft                                             July 28, 2009
Expires: January 29, 2010


      Revisions to the BGP 'Minimum Route Advertisement Interval'
                       draft-ietf-idr-mrai-dep-01

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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.




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Table of Contents

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










































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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].


2.  Background

   The Minimum Route Advertisement Interval (MRAI) timer is specified in
   RFC4271 [BGP].  This timer acts to rate-limit updates, on a per-
   destination basis.  [BGP] 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.

   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.


3.  Revision

   The suggested default values for the
   MinRouteAdvertisementIntervalTimer given in RFC4271 [BGP] 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.


4.  IANA Considerations

   There are no requests made to IANA in this document.


5.  Security Considerations

   This document raises no new security considerations.


6.  Normative References

   [BGP]      Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.



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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", RFC 2119, BCP 14, February 2001.


Author's Address

   Paul Jakma
   2/1, 5 Moir St.
   Glasgow  G1 5AE
   Scotland

   Email: paul@jakma.org







































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