nanog mailing list archives
Re: BCP38 - Internet Death Penalty
From: Leo Bicknell <bicknell () ufp org>
Date: Thu, 28 Mar 2013 10:58:03 -0700
In a message written on Thu, Mar 28, 2013 at 01:10:53PM -0400, William Herrin wrote:
Since you've configured a prefix list to specify what BGP routes you're willing to accept from the simple multihomed customer (you have, right?) why set a source filter from the same data instead of trying to build it from routing table guesswork?
In the simplest case I described (user has for instance one netblock) the packet filter will match the routing filter, and doing what you described would not be a huge extra burden. Howver, it is still a burden, it's writing everything twice (prefix list plus ACL), and it's making configs longer and less readable. But the real power here comes by applying this filter further up the food chain. Consider peering with a regional entity at an IX. Most people don't prefix filter there (and we could have a lively argument about the practicality of that), so the prefix list might be something like: deny my_prefix/foo le 32 permit 0.0.0.0/0 le 24 With a max-prefix of 100. That doesn't turn into a useful packet filter for the peer, but using my method the peer could be RPF filtered based on what they send, automatically. -- Leo Bicknell - bicknell () ufp org - CCIE 3440 PGP keys at http://www.ufp.org/~bicknell/
Attachment:
_bin
Description:
Current thread:
- Re: BCP38 - Internet Death Penalty, (continued)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 27)
- Re: BCP38 - Internet Death Penalty Jack Bates (Mar 27)
- Re: BCP38 - Internet Death Penalty Saku Ytti (Mar 27)
- RE: BCP38 - Internet Death Penalty Adam Vitkovsky (Mar 28)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 28)
- RE: BCP38 - Internet Death Penalty Adam Vitkovsky (Mar 28)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 28)
- Re: BCP38 - Internet Death Penalty Leo Bicknell (Mar 28)
- Re: BCP38 - Internet Death Penalty Chris Adams (Mar 28)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 28)
- Re: BCP38 - Internet Death Penalty Leo Bicknell (Mar 28)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 28)
- RE: BCP38 - Internet Death Penalty Adam Vitkovsky (Mar 29)
- Re: BCP38 - Internet Death Penalty William Herrin (Mar 29)
- Re: BCP38 - Internet Death Penalty Dobbins, Roland (Mar 28)
- Re: BCP38 - Internet Death Penalty John Curran (Mar 27)
- Re: BCP38 - Internet Death Penalty Mark Andrews (Mar 27)
- Re: BCP38 - Internet Death Penalty Paul Ferguson (Mar 27)
- Re: BCP38 - Internet Death Penalty Valdis . Kletnieks (Mar 27)
- Re: BCP38 - Internet Death Penalty Jason Ackley (Mar 27)
- Re: BCP38 - Internet Death Penalty Mark Andrews (Mar 27)