<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 TRANSITIONAL//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=UTF-8">
<META NAME="GENERATOR" CONTENT="GtkHTML/4.8.5">
</HEAD>
<BODY>
Hello.<BR>
<BR>
We are using bird with several upstream providers, all of them with a<BR>
share of traffic.<BR>
<BR>
We are in the process of shutting down one of them but we are unsure<BR>
how to proceed to minimize loss of traffic.<BR>
<BR>
We have been reading and looking for general recommendations but it is<BR>
not clear (besides using graceful shutdown which is not supported by<BR>
the upstream we want to shutdown).<BR>
<BR>
We have been looking at mailing list but we haven't found anything<BR>
treating this matter.<BR>
<BR>
So far, solutions we have come up are:<BR>
<BR>
1) Use AS-path prepend to increase metric on the uptstream to be<BR>
shutted down and once nearly no traffic comes in through that link, shutdown<BR>
BGP and unplug. Something like:<BR>
<BR>
export filter { <BR>
<BR>
if source = RTS_STATIC then { # Export only static routes <BR>
# Assign our community <BR>
bgp_community.add((65000,64501)); <BR>
# Artificially increase path length <BR>
# by advertising local AS number twice <BR>
if bgp_path ~ [= 65000 =] then <BR>
bgp_path.prepend(65000);<BR>
bgp_path.prepend(65000);<BR>
accept; <BR>
} <BR>
reject; <BR>
}; <BR>
<BR>
2) Another solution is to just shutdown BGP session but leave upstream<BR>
connected and configured (so outdated routers we still reach us...).<BR>
<BR>
3) And the obvious, just shutdown BGP session and unplug the cable.<BR>
<BR>
It would be great to know your opinion and what's the recommended way<BR>
to proceed. <BR>
<BR>
What do you think?<BR>
<BR>
Many thanks<BR>
Best Regards.<BR>
<BR>
<BR>
<BR>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%">
<TR>
<TD>
-- <BR>
Francis Brosnan Blázquez <<A HREF="mailto:francis.brosnan@aspl.es">francis.brosnan@aspl.es</A>><BR>
ASPL -- Advanced Software Production Line, S.L.
</TD>
</TR>
</TABLE>
</BODY>
</HTML>