[nsp] Typical Prefix filters - greater than /24's dropped?
Vincent De Keyzer
vincent at dekeyzer.net
Thu Nov 20 10:35:16 EST 2003
Not sure this test is really relevant, but here is what I see on my bi-homed
alfonso>sh ip bgp | i /2[5-9]
*>i184.108.40.206/26 a.b.c.d 100 0 8220 i
*>i220.127.116.11/26 a.b.c.d 100 0 8220 i
*>i18.104.22.168/27 a.b.c.d 100 0 8220 i
*>i22.214.171.124/25 a.b.c.d 100 0 8220 i
*>i126.96.36.199/25 a.b.c.d 100 0 8220 20566 i
*>i188.8.131.52/26 a.b.c.d 100 0 8220 ?
alfonso>sh ip bgp | i /3[0-2]
So only one of my two transit providers seems to pass me on routes with a
longer prefix than /24, and all but one of the routes are originated in his
own AS (the last one being probably originated by one of its customers).
So I imagine that yes, many transit providers do filter those.
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Sam Stickland
> Sent: jeudi 20 novembre 2003 11:59
> To: Cisco Nsp
> Subject: [nsp] Typical Prefix filters - greater than /24's dropped?
> I'm trying to get a feel for the sort of prefix filters that
> are typically in use on the backbones and transit providers.
> Are prefixes longer than /24's typically filtered out?
> cisco-nsp mailing list cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco> -nsp
> archive at
More information about the cisco-nsp