Yes, my original quote wasn’t exactly word-for-word from the standard, but it 
was semantically identical.

I’m sure we can find corner cases, but it’s clear that the vast majority of BGP 
users are following the standard.  Anycast isn’t a violation of the standards 
because it’s defined in BGP as a single destination address having multiple 
routing paths to two or more endpoints.

 -mel

On May 30, 2019, at 12:48 PM, William Herrin 
<b...@herrin.us<mailto:b...@herrin.us>> wrote:

> On Thu, May 30, 2019 at 10:58 AM Mel Beckman 
> <m...@beckman.org<mailto:m...@beckman.org>> wrote:
> > Come on now. The definition of an autonomous system is well established in 
> > RFC1930, which is still Best Current Practice:
> > https://tools.ietf.org/html/rfc1930#section-3

Your quote wasn't from the RFC. Sorry, my google fu is only good enough to find 
your actual quote, not the similar one you didn't reference.

> > An AS is a connected group of one or more IP prefixes run by one
> >       or more network operators which has a SINGLE and CLEARLY DEFINED
> >       routing policy.

Interesting but it bears little resemblance to modern practice. Consider an 
anycast announcement, for example, where multiple distributed servers at 
isolated pops terminate the packet. Consider Amazon where both region-local 
unicast announcements and global anycast announcements all originate from AS 
16509. Indeed the whole concept of traffic engineering rests on the premise 
that an AS' routing policy is NOT the same at every border.

Regsards,
Bill Herrin


--
William Herrin
b...@herrin.us<mailto:b...@herrin.us>
https://bill.herrin.us/

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