Re: Regional AS model

[Michael Hallgren <m.hallgren () free fr>]

Le jeudi 24 mars 2011 à 14:26 -0700, Bill Woodcock a écrit :
> On Mar 24, 2011, at 1:47 PM, Patrick W. Gilmore wrote:
> > On Mar 24, 2011, at 3:40 PM, Owen DeLong wrote:
> > > On Mar 24, 2011, at 12:42 PM, Zaid Ali <zaid () zaidali com> wrote:
> > >
> > > > I have seen age old discussions on single AS vs multiple AS for backbone and datacenter design. I am particularly 
> > > > interested in operational challenges for running AS per region e.g. one AS for US, one EU etc or I have heard 
> > > > folks do one AS per DC. I particularly don't see any advantage in doing one AS per region or datacenter since 
> > > > most of the reasons I hear is to reduce the iBGP mesh. I generally prefer one AS  and making use of 
> > > > confederation. 
> > >
> > > If you have good backbone between the locations, then, it's mostly a matter of personal preference. If you have 
> > > discreet autonomous sites that are not connected by internal circuits (not VPNs), then, AS per site is greatly 
> > > preferable.
> >
> > We disagree.
> > Single AS worldwide is fine with or without a backbone.
> > Which is "preferable" is up to you, your situation, and your personal tastes. 
>
>
> We're with Patrick on this one.  We operate a single AS across seventy-some-odd locations in dozens of countries, 
> with very little of what an eyeball operator would call "backbone" between them, and we've never seen any potential 
> benefit from splitting them.  I think the management headache alone would be sufficient to make it unattractive to us.
>
>                                 -Bill

Right. I think that a single AS is most often quite fine. I think our
problem space is rather about how you organise the routing in your AS.
Flat, route-reflection, confederations? How much policing between 
regions do you feel that you need? In some scenarios, I think 
confederations may be a pretty sound replacement of the multiple-AS
approach. Policing iBGP sessions in a route-reflector topology? Limits?
Thoughts?

Cheers,

mh

>