Re: [swinog] AS3303 overlapping prefix

On 03. 04. 11 13:01, Simon Leinen wrote:

Andy Grawehr writes:

...

when i check our prefix 193.105.5.0/24 on www.ris.ripe.net i get an overlapping prefix: 192.0.0.0/3 announced by AS3303.

Google "AS3303 semi-default". AS3303 announces this /3 to their customers and possibly use it internally. It's part of an elaborate mechanism to trade off routing table size against path quality.

With 3303, you can filter these annoucements using bgp community attribute 3303:9999 Additionnaly it contains the no-export attribute too.

Look for "bgp filtering swinog" on google, you'll find the presentation Andre Chapuis made at swinog 7 back in 2003.

http://www.swinog.ch/meetings/swinog7/BGP_filtering-swinog.ppt (look for "semi-default")