[j-nsp] Re: M5 - outbound load balancing

Fouant, Stefan A stefan.fouant at mci.com
Wed Jan 19 19:11:31 EST 2005

I see the error in my ways ;)

So just for my understanding, please clarify...

If the two peers were in the same AS but were configured under different
peer groups, each configured with multipath, would this still work?  What if
one of the peer groups didn't have multipath configured.  Thanks,


> -----Original Message-----
> From: Pedro Roque Marques [mailto:roque at juniper.net]
> Sent: Wednesday, January 19, 2005 5:14 PM
> To: Fouant, Stefan A
> Cc: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] Re: M5 - outbound load balancing
> Stefan A Fouant writes:
> > Hi, The "show route extensive" output shows that the second path is
> > inactive because of the Router-ID which indicates that multipath is
> > not working correctly - proper operation of multipath skips the
> > Router-ID and Peer-ID evaluation during the BGP Path Selection
> > algorithm.  I don't think multipath is working in your case because
> > you've configured these two peers under different groups.
> Close, but not quite.
> multipath will not group together paths received from different
> ASes. The reason being that BGP can only advertise one path.
> If you setup BGP to accept path from different ASes, then as-path loop
> detection is being defeated if this route is subsequently advertised
> via BGP, as the forwarding path no longer corresponds to the routing
> path.
>   Pedro.

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