Re: well-known Anycast prefixes

[Joe Provo <nanog-post () rsuc gweep net>]

On Tue, Mar 19, 2019 at 11:52:19AM -0700, Damian Menscher via NANOG wrote:
> Careful thought should be given into whether the BGP community means "this
> is an anycast prefix" vs "please hot-potato to this prefix".
> Latency-sensitive applications may prefer hot-potato to their network even
> if it's not technically an anycast range, as their private backbone may be
> faster (less congested) than the public internet.

To this point, it is pretty clear that any WK community covering this
will get [ab]used in a way that the prefix annoucer wishes. We'll then 
see operators only accepting the WKC if it matches their prefix lists
of known entities, getting us back to "hey maybe this should just be 
a registry I could reference".

Woody, maybe generate route-sets to publish in RPSL (RADB?), one per 
address-family, of observed anycasters?  It might be reasonable to do 
so in a format others can emulate if they wish to create/provide their 
own lists?

Cheers,

Joe

> Damian
>
> On Tue, Mar 19, 2019 at 10:57 AM Siyuan Miao <aveline () misaka io> wrote:
>
> > A Well-known BGP community will be better.
> >
> > You'll need to rewrite next hop or do something similar if AnyCast
> > prefixes are learnt from a multi hop BGP feed, and it made the
> > configuration more complicated and difficult to debug.
> >
> > On Wed, Mar 20, 2019, 01:48 Fredy Kuenzler <kuenzler () init7 net> wrote:
> >
> > > Am 19.03.19 um 18:39 schrieb Bill Woodcock:
> > > > > On Mar 19, 2019, at 10:12 AM, Fredy Kuenzler <kuenzler () init7 net>
> > > > > wrote: I wonder whether anyone has ever compiled a list of
> > > > > well-known Anycast prefixes.
> > > >
> > > > I don???t know of one.
> > > >
> > > > It seems like a good idea.
> > > >
> > > > BGP-multi-hop might be a reasonable way to collect them.
> > > >
> > > > If others agree that it???s a good idea, and it???s not stepping on
> > > > anyone???s toes, PCH would be happy to host/coordinate.
> > >
> > > Thanks for the effort, much appreciated.
> > >
> > > Am 19.03.19 um 18:40 schrieb Joe Provo:
> > > > I think one would want that internal and no rely upon someone else
> > > > maintaining it.  You might check if Oracle followed up on the
> > > > Renesys/Dyn work documented:
> > > > https://dyn.com/wp-content/uploads/2014/07/NANOG59_Anycast.pdf
> > > >
> > > > ...where there were ~600 anycast v4 prefixes at the time.
> > >
> > > That's a lot %-]
> > >
> > > Maybe a well-known community (similar to RFC7999) could be defined and
> > > every Anycast operator could tag his prefixes? That's likely a better
> > > idea than manually maintain some list somewhere.
> > >
> > > --
> > > Fredy Kuenzler
> > >
> > > Init7 (Switzerland) Ltd.
> > > AS13030
> > > Technoparkstrasse 5
> > > CH-8406 Winterthur
> > > Skype:   flyingpotato
> > > Phone:   +41 44 315 4400
> > > Fax:     +41 44 315 4401
> > > Twitter: @init7 / @kuenzler
> > > http://www.init7.net/

-- 
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Joe Provo / Gweep / Earthling