Quest-How network 20.0.0.0/172.16.0.0/192.168.1.0 with wildcard 0.0.0.

[krahulbgp]

we to filter some specific prefixes, 

Quest-How network 20.0.0.0/172.16.0.0/192.168.1.0 with wildcard 0.0.0.0 used ? is wildcard mask correct ? also subnet mask 255.0.0.0 with wildcard 0.0.0.0 ? team plz explain 

[Flavio Miranda]

Hi

  Dont make sense to me. Not because the wildcard but the Access-List is structured as "source" and "Destination" and a destination with 255.0.0.0  dont make sense.

[Jon Marshall]

That would allow the following routes to be accepted - 

20.0.0.0/8
172.16.0.0/24
192.168.1.0/24

and only those exact matching routes. 

Jon

[David Ruess]

Hello,

ACLs act differently with BGP. When using an extended access-list with source AND destination the source will match the network part of the route, while the destination will match the network mask of the route. 

BGP Access Control Lists – Route Protocol

-scroll down to the end

You can also find it in Chapter 12 of the ENARSI 300-410 certification book with Advanced BGP

Hope that helps

-David