School of Computing Science, Uni. of Glasgow

Sir Alwyn Williams Building Glasgow G12 8QQ Scotland paulj@dcs.gla.ac.uk

Routing Inter-Domain Routing BGP IDR MRAI Convergence This document updates the specification of the BGP MRAI timer in , by deprecating the previously recommended values and by allowing for withdrawals to be exempted from the MRAI.

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 .

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

The suggested default values for the MinRouteAdvertisementIntervalTimer given in 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.

There are no requests made to IANA in this document.

This document raises no new security considerations.