Blocking local routes advertised to BGP

[davidjdv]

OK - but I suppose that no routes are advertised at all now (since the EBGP group is inactive) 

You can double-check this with the 'show route advertising-protocol bgp ...' commands described above.

Please let us know exactly what you want to advertise (and/or block) and we can help you with the config.

Cheers,

/david 

[PeteW]

Yep, thats ok and I appreciate that there are no routes advertised currently. It alleviates the current problem until we can work out the routes that "should" be advertised via iBGP.

Pete 

[erdems · Accepted solution]

Hi PeteW,

 As David pointed out, you may want to alter your import/export policies to cover 'safety' mechanisms

as the first couple of terms, like the following example:

policy-statement ebgp-export {
    term no-small-prefixes {
        from {
            route-filter 0.0.0.0/0 prefix-length-range /25-/32;
        }
        then reject;
    }
    term no-martians {
        from {
            route-filter 0.0.0.0/8 orlonger;
            route-filter 10.0.0.0/8 orlonger;
            route-filter 127.0.0.0/8 orlonger;
            route-filter 169.254.0.0/16 orlonger;
            route-filter 172.16.0.0/12 orlonger;
            route-filter 192.0.2.0/24 orlonger;
            route-filter 192.168.0.0/16 orlonger;
            route-filter 198.18.0.0/15 orlonger;
            route-filter 224.0.0.0/3 orlonger;
        }
        then reject;
    }
    term no-privates {
        from as-path private;
        then reject;
    }
    term accepted-prefixes { ## <<< this is where you start 'accepting'

       then accept;
    }
}

Applying similar import policies to your ebgp sessions (e.g. start with rejecting the 'usual suspects' then accept what you want later) might be a good idea as well.

I had read somewhere that paranoia was one's best friend while configuring BGP, and I still do believe that :-)

Cheers,

Erdem

[PeteW]

Many thanks for your assistance guys, the issue is now resolved and all appropriate routes are being advertised