[nsp] BGP filter issue

[Alban Dani]

Hello,

 

Recently I experienced a weird issue with our internet connection.

 

We have a Cisco 7200 connected to our ISP ( Verizon).

A month ago we applied a bgp filter on the inbound that would accept bgp
routing updates only from our neighbor AS and the one next to it.

 

ip as-path access-list 6 permit ^19262$

ip as-path access-list 6 permit ^19262 [0-9]+$

ip as-path access-list 6 deny .*

 

Last week we started having issues with the internet connection for
several employees that connected remotely to our network. After some
research we figured that people that were connected to ISP-s that were
no more then two AS hops from us were having the problem ( and we could
find their networks in the bgp table ). On the other hand people who
were more then two AS hops away were just fine. Their networks could not
be found in the bgp table (as excpected  because of the filter ) and
they were taking the default route outside.

 

We took the filter out today and everything is back to normal.

 

Can anybody explain this? Is it a bug? A design flow? Is it the ISP?

 

 

Thanks in advance

 

Alban