Subject: [Idr] Would one AS announce to another AS two different routes for the same destination?

From: Hongwei Zhang <[email-masked]>
Date: Fri, 07 Nov 2003 17:19:09 -0500

Hi,

I wonder if, in practice, two BGP speakers within the same AS would 
announce to another AS two different routes for the same destination? If 
this could happen, I wonder if it is a common practice or not?

Thanks and have a nice weekend,

Hongwei

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From: Curtis Villamizar <[email-masked]>
Date: Fri, 07 Nov 2003 17:57:47 -0500

> Thanks and have a nice weekend,

If you mean different next hop, that happens all the time.  Most
prefix are announced 2-5 times into a given IBGP.

If you mean different AS path, that happens too if the announcing AS
is using IGP cost as a matter of preference and has diffent private
peering near your peerings.  This doesn't happen as often but does
happen and almost any AS can find a lot of these cases.

Is there a reason for the question?

Curtis

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From: Curtis Villamizar <[email-masked]>
Date: Fri, 07 Nov 2003 17:57:47 -0500

Curtis