Multi site BGP Routing design

Ivan Pepelnjak ip at
Tue Jun 9 20:45:59 UTC 2009

> I am thinking the multiple ASN route is the cleanest but the 
> idea of letting a default gateway (via static route maybe) 
> out the local upstream connection to reach the other site 
> when the backnet link is down sounds like it would work with 
> minimal to no headaches but it just some how seems like a 
> duct tape job. Does this sort of technique have any 
> significant flaws or concerns associated with it?

It's a static route, so you're never sure the remote end (upstream router)
is truly alive. In this respect, it would be much better to receive default
route over BGP (if the upstream carrier is willing to implement it).

On the other hand, it's a last-resort mechanism, so you'd only use it if
everything else fails (and you don't care how reliable it is). Just make
sure it's well documented and understood ... and think about what will
happen when you add a third carrier to one of the sites.

Last but not least, you could use reliable static routing (static route tied
to ping tests).

Just my $0.002 :)

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