Re: Traffic engineering and peering for CDNs

["Wolff, Nick" <nwolff () oar net>]

On 6/7/16, 2:46 AM, "NANOG on behalf of Mark Tinka"
<nanog-bounces () nanog org on behalf of mark.tinka () seacom mu> wrote:

> On 6/Jun/16 20:03, Tom Smyth wrote:
>
> > as far as im aware ... a friend of mine on INEX in Ireland said most
> > cdns
> > use source ip of the DNS requests to determine which network to direct
> > them
> > to ... so if you use you have your own resolver on  an ip address  in
> > your
> > network range cdns can accurately determine what network the request is
> > comming from and determine what  ip address / what network that the cdn
> > has
> > nearest to your network...
> >
> > ff you use 3rd party  dns servers for your clients... you may not get an
> > optimal ip answer for your dns queries from the CDNS involved
>
> Some CDN's use DNS (in addition to latency, congestion levels, busy
> state, e.t.c.).
>
> Others use Anycast routing, which I tend to prefer. The problem is the
> latter run a network while the former may typically not.
>
> Mark.

Also some companies make layer 7 decisions for their CDN¹s in conjunction
with these other methods. Their applications makes a decision on what host
to send you to based on routing information, your source address, and
other accumulated data.