Re: CDNs for carriers

[Jared Mauch <jared () puck nether net>]

> On Jun 29, 2015, at 9:59 AM, Mike Hammett <nanog () ics-il net> wrote:
>
> Simple flows wouldn't necessarily tell you if you're pulling a bunch from a Netflix caching box on your upstream 
> somewhere. You'd think you had a huge amount going to your current upstream because technically you do, but a local 
> cache or peer could alter that significantly. As we've been starting up our IX, we're finding that we can send lists 
> of ASNs and prefixes and the various CDNs will tell us how much traffic they see going to our customers. Combine that 
> with what flows tell you and I think you've got a good approach. 
>
> What are some good approaches to determining traffic levels to not only ASNs, but also that ASN's downstream ASNs? 
> You may have ASNs A, B, C, D and E in your flows. Say none of them represent more than 5% of your traffic by 
> themselves. If B, C, D and E all purchase transit from A and you can reasonably peer with A, you actually can move 
> 25% of your traffic over to a peer. Maybe there is no good approach at doing that without a bunch of manual work or 
> paying someone else to do it. 
>
> Looking at some stats from one of our customers that is also going through Equinix Chicago, for their average inbound 
> ~37% of traffic was Netflix, Google was 34% and the next highest was Apple at 5%. Note that Akamai had left Chicago 
> Equinix by this point, so they wouldn't be reflected in those numbers. Those percentages are percent of all traffic 
> they send to Equinix. I believe about 2/3s of their total transit went to Equinix when that got turned up. Their 
> total traffic went up once joining the Equinix IX, presumably because they were now bypassing some congestion 
> somewhere. 

Sure.  There are a lot of dynamics to consider.  It’s fairly easy to look at TCP speeds and retransmissions to 
determine the link speed involved.  I’ve seen many CDNs quickly identify congested or paths without congestion and 
engage in some adaptive behaviors.

This being said, there is not a single solution to everything.  Chris mentioned using DNS, which is a nice method 
assuming you see all the queries within your traffic cone.

- Jared