I don’t think, anyone has proposed to use ‘’reserved ASNs” as a BCP, example of “ab”use of ASN0 is a de-facto artifact (unfortunate one). My goal would be to provide a viable source of information to someone who is setting up a new ISP and has a very little clue as where to start. Do’s and don’t’s wrt inter-domain communities use.
I really enjoyed the difference RFC7938 (Use of BGP for Routing in Large-Scale Data Centers) made, literally 100s of companies have used it to educate themselves/ implemented their DC networking. Cheers, Jeff >> On Sep 9, 2020, at 10:04, adam via NANOG <nanog@nanog.org> wrote: > > I don’t agree with the use of reserved ASNs, let alone making it BCP, cause > it defeats the whole purpose of the community structure. > Community is basically sending a message to an AS. If I want your specific AS > to interpret the message I set it in format YOUR_ASN:<community value>, your > AS in the first part of the community means that your rules of how to > interpret the community value apply. > Turning AS#0 or any other reserved AS# into a “broadcast-AS#” in terms of > communities (or any other attribute for that matter) just doesn’t sit right > with me (what’s next? multicast-ASNs that we can subscribe to?). > All the examples in Robert’s draft or wide community RFC, all of them use an > example AS# the community is addressed to (not some special reserved AS#). > > Also should something like this become standard it needs to be properly > standardized and implemented as a well-known community by most vendors (like > RFCs defining the wide communities or addition to standard communities like > no_export/no_advertise/…). This would also eliminate the adoption friction > from operators rightly claiming “my AS my rules”. > > adam > > > From: NANOG <nanog-bounces+adamv0025=netconsultings....@nanog.org> On Behalf > Of Douglas Fischer via NANOG > Sent: Tuesday, September 8, 2020 4:56 PM > To: NANOG <nanog@nanog.org> > Subject: BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN > reserved to "export-only-to"?' > > Most of us have already used some BGP community policy to no-export some > routes to some where. > > On the majority of IXPs, and most of the Transit Providers, the very common > community tell to route-servers and routers "Please do no-export these routes > to that ASN" is: > > -> 0:<TargetASN> > > So we could say that this is a de-facto standard. > > > But the Policy equivalent to "Please, export these routes only to that ASN" > is very varied on all the IXPs or Transit Providers. > > > With that said, now comes some questions: > > 1 - Beyond being a de-facto standard, there is any RFC, Public Policy, or > something like that, that would define 0:<TargetASN> as "no-export-to" > standard? > > 2 - What about reserving some 16-bits ASN to use <ExpOnlyTo>:<TargetASN> as > "export-only-to" standard? > 2.1 - Is important to be 16 bits, because with (RT) extended communities, any > ASN on the planet could be the target of that policy. > 2.2 - Would be interesting some mnemonic number like 1000 / 10000 or so. > > -- > Douglas Fernando Fischer > Engº de Controle e Automação
