RE: bgp question

Marcin,

You might want to reference this page, in its simplest form, you just need to aggregate /22 to each of your providers and announce the more specific routes out of the preferred gateway. You could also enable a secondary failover by announcing out the /23's instead. Then for each of your providers routes you could get partial (customer + their routes... or whatever they call it) + default and set the local pref to 200 for each of those received routes. Set next-hop-self on each of the iBGP peers and that should do the trick.

This is the page I'm referring to:

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml#conf5

-ryan

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of Marcin Zgola
Sent: Tuesday, October 27, 2009 11:59 AM
Cc: Cisco certification
Subject: bgp question

What would be the best way to do this:

I have 3 routers connected in "triangle mode" and each router has its
own ISP connection.

Connection to ISP using eBGP (3 different ISPs, three different AS #)
Connection between each other iBGP

Anyway, here is what I want

I have couple of /22 blocks.

I advertise /24 to these ISPs, in case of the failure I do conditional
advertisement , and it works.

Example 1.1.0.0/22 divides into 1.1.0.0/24 , 1.1.1.0/24 , 1.1.2.0/24 ,
1.1.3.0/24

I want to 1.1.0.0/24, and 1.1.1.0/24 to go out via ISP1
1.1.2.0, and 1.1.3.0 via ISP2, but I want ISP2 to also advertise /22, so
in case ISP1 fails I will have my failover without using conditional
advertisements.

Any config examples out there?

Thanks

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Received on Tue Oct 27 2009 - 14:29:00 ART