If you have multiple transit providers and still want to be able to push traffic to the best path (no default route), then maybe a filter that will accept only AS Path 2/3 or shorter per transit provider, and a default route for the rest. You will get significantly less prefixes, and BGP path selection will work “locally”. For far away prefixes though (more than 4 ASes away), you will not (always) pick the best path.
> On 15 May 2019, at 16:36, Dan White <dwh...@olp.net> wrote: > > We recently filtered out >=/24 prefixes since we're impacted by 768k day. > I'm attaching our lightly researched list of exceptions. I'm interested in > what others' operational experience is with filtering in this way. > > Filtering /24s cut our table down to around 315K. > > On 05/15/19 13:43 +0200, Baldur Norddahl wrote: >> Hello >> >> This morning we apparently had a problem with our routers not handling the >> full table. So I am looking into culling the least useful prefixes from our >> tables. I can hardly be the first one to take on that kind of project, and I >> am wondering if there is a ready made prefix list or similar? >> >> Or maybe we have a list of worst offenders? I am looking for ASN that >> announces a lot of unnecessary /24 prefixes and which happens to be far away >> from us? I would filter those to something like /20 and then just have a >> default route to catch all. >> >> Thanks, >> >> Baldur >> > > -- > Dan White > BTC Broadband > Network Admin Lead > Ph 918.366.0248 (direct) main: (918)366-8000 > Fax 918.366.6610 email: dwh...@mybtc.com > http://www.btcbroadband.com > <punt-768k-day.txt>
