Re: intra-AS messaging for route leak prevention

[Mark Tinka <mark.tinka () seacom mu>]

On 6/Jun/16 17:54, Job Snijders wrote:

> There is the "human network" approach, where operators share information
> with each other which be used to generate config to help block
> "unlikely" announcements from eBGP neighbors.
>
> For instance AT&T and NTT agreed (through email) that there should be no
> intermediate networks between 2914 & 7018, therefore NTT blocks
> announcements that match as-path-regexp '_7018_' on any and all eBGP
> sessions, except the direct sessions with 7018. NTT calls this concept
> "peerlocking".

I suppose if one is performing prefix- and ASN-based filtering, then you
"should" not learn peer paths via customers. If you augment that with
AS_PATH-based filtering, you "will not" learn peer paths via customers.

One thing we do to reduce opportunistically hazardous vectors is to not
learn customer paths via peers.

Mark.