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BGP Multiple ISPs, Multiple Locations

I will be using my own AS number and /24 to advertise as follows:

Primary Data Center Location #1:

Router A -ISP A

Router B - ISP B

Backup Data Center Location #2:

Router A - ISP A

Router B - ISP C    

I want to create the failover scenario where if ISP A goes down, traffic fails over to ISP B. If Primary Data Center fails, traffic fails over to Backup Data Center, ISP A. If Backup Data Center ISP A fails, traffic fails to ISP C.

Can someone give me some guidance on the routiung and general config for the routers?


Cisco Employee

BGP Multiple ISPs, Multiple Locations

Hi Christopher,

One of the multiple ways you can achieve this, is to use BGP conditional advertisement. This would allow you to advertise the local /24 via only one router at a time and in the priority you had given. This would obviously require that you configure an iBGP mesh between the four routers so that they know at all time which routers are up and have connectivity to the Internet. Please refer to the following document for more information on conditional advertisement.


Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
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