Route Flapping and Bird - RFD and MRAI

[Ondrej Zajicek]

On Mon, Feb 14, 2022 at 10:48:40AM -0300, Douglas Fischer wrote:
> Passing by here to drop another ping on the MRAI - Minimum Route
> Advertisement Interval in the BIRD, and also on the RFD -
> Route-Flap-Dampening.

Hi

Several people ask us recently about MRAI / route flap damping, we
will likely put some effort to implement it.

There are two basic ways how to do it:

1) In export-part of BGP protocol, where prefixes are stored to transmit,
in a per-peer way. This is AFAIK how RFC 4271 assumed MRAI works. It could
be configured per-peer, but has disadvantage that it requires memory for
routes pushed for export but postponed for MRAI (these are stored separatedy
for each peer).

2) In routing table, by temporarily 'suspend' paths that change too often (so
they cannot be elected as best paths). This is AFAIK how RFC 2435 Route flap
damping works.

Seems to me that both approaches make sense even together. We will
discuss that internally to see how we will implement that.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."