Re: DNS Anycast as traffic optimizer?

[Patrick W Gilmore <patrick () ianai net>]

On Sep 1, 2004, at 2:17 PM, Steve Francis wrote:

> >    > ...how good/bad using DNS anycast is as a kludgey traffic 
> > optimiser?
> >
> > I'd hardly call it a kludge.  It's been standard best-practice for 
> > over a
> > decade.
> I thought it was standard best practice for availability, like for 
> root name servers.  I thought it was not a good "closest server" 
> selection mechanism, as you'll be going to the closest server as 
> determined by BGP - which may have little relationship to the server 
> with lowest RTT.
> It'd be nice to see some metrics wither way....

I don't know any papers, but I have see real world examples where a 
well peered network was adjacent to 5 or more anycasted server, 3 in 
the US, one in Europe, and one in Asia.  The network was going to the 
Asian server, because that router had the lowest Router ID.

Not exactly sure how that makes it "much higher than Akamai", but 
that's what I've seen.

--
TTFN,
patrick


> >    > THe question is, what is that "some" relationship?  80% as good 
> > as
> >    > Akamai?  Terrible?
> >
> > Should be much higher than Akamai, since that's not what they're
> > optimizing for.  If you want nearest server, anycast will give you 
> > that
> > essentially 100% of the time.  Akamai tries to get queries to servers 
> > that
> > have enough available capacity to handle the load.  Since they're 
> > handling
> > bursty, high-bandwidth applications, rather than DNS.
> >
> >                                -Bill