implement carp demotion control for bgpd.

sessions can be configured to modify the carp demotion counter for a
given interface group (usually, "carp", which has all carp interfaces)
when the session is not established. once the session is established for
60 seconds, the demotion is cleared.
this, used correctly, can prevent a bgpd-box which lost all sessions (and
thus has no routes) to be carp master, while the backup has sessions.
thought through and partially hacked on a drive from calgary to vancouver
with ryan, ok claudio

1 files changed, 16 insertions, 1 deletions

diff --git a/usr.sbin/bgpd/bgpd.conf.5 b/usr.sbin/bgpd/bgpd.conf.5
index 0dafcfd45d1..75036cf9771 100644
--- a/usr.sbin/bgpd/bgpd.conf.5
+++ b/usr.sbin/bgpd/bgpd.conf.5
@@ -1,4 +1,4 @@
-.\" $OpenBSD: bgpd.conf.5,v 1.70 2006/05/26 04:02:59 deraadt Exp $
+.\" $OpenBSD: bgpd.conf.5,v 1.71 2006/06/17 14:06:09 henning Exp $
 .\"
 .\" Copyright (c) 2004 Claudio Jeker <claudio@openbsd.org>
 .\" Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -425,6 +425,21 @@ are supported) are announced during the capabilities negotiation.
 Only routes for that address family and subsequent address family will be
 announced and processed.
 .Pp
+.It Ic demote Ar group
+Increase the
+.Xr carp
+demotion counter on the given group, usually
+.Ar carp ,
+when the session is not in state
+.Em ESTABLISHED .
+The demotion counter will be increased as soon as bgpd starts and decreased
+60 seconds after the session went to state
+.Em ESTABLISHED.
+For neighbors added at runtime, the demotion counter is only increased after
+the session has been
+.Em ESTABLISHED
+at least once before dropping.
+.Pp
 .It Ic depend on Ar interface
 The neighbor session will be kept in state
 .Em IDLE