Re: [nsp] Multi-Homing without BGP

From: Tony Tauber (ttauber@genuity.net)
Date: Fri Oct 13 2000 - 11:09:10 EDT


On Fri, 13 Oct 2000, Cliff Judge wrote:

>
> I would suggest balancing on a per-packet basis in this kind of situation
> (i.e. don't enable ip route-cache on the interfaces)...you cannot control
> the routes you are placing into your cache this way, so it is best to
> throw the packets evenly out both interfaces.

Excuse me?!? Why is it best?

I'll tell you why it's worse:

Chosing between two providers to some distant location the delay
is liable to vary considerably thus, there's a high probability
of packets arriving out of order which will likely cause
retransmission requests from the destination IP stack which
thinks it's missing intermediate segments.
Excessive retransmissions will not only waste bandwidth but slow
effective data transfer between application layers significantly.

I'm from the camp of thinking that originating your routes
via BGP from your own AS is the cleanest way to multihome;
however, if you're just recieving some sort of default from
your upstreams, all above still holds.

Tony



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