BGP route filtering

[dpugalendi.d]

How to stop isp1 routes advertisement via isp2 on Bgp... The problem is when my spoke isp1 mpls down... Still it is getting routes via isp2

[lthangli]

Hi,

To assist you better, can you come a bit clear about the issue and the topology?

Thanks,

Lal

[dpugalendi.d]

In General , if u share the best routing filter to isolate ISP1 and ISP2 it will be helpfull

because it needs multiple scenario where one link and multiple links at spoke side.

The problem is ISP1 is in mesh topology , so when the ISP1 is down it is showing alternate route via ISP2 .. we need to avoid the same.

[dpugalendi.d]

i heard some distribution list to do the same .. kindly help me on this ...

[Richard Burts · Accepted solution]

I do not have an understanding of your topology or of the relationship between ISP 1 and ISP 2 and therefore can not be sure how well my suggestion will work. But here is what I frequently use when I want to be sure that routes learned from ISP 1 do not get advertised to ISP 2.

ip as-path access-list 10 permit ^$

router bgp 123

 neighbor 1.2.3.4 filter-list 10 out

HTH

Rick

[dpugalendi.d]

thanks