Traffic engineering and peering for CDNs

Mon Jun 6 14:06:24 UTC 2016

On Mon, 6 Jun 2016, Graham Johnston wrote:

> What I am not understanding about the respective CDN's network wherein 
> they don't send traffic to me through a consistent path? Is the content 
> coming from widely different places and rather than transport it across 
> their own network from a remote site they would rather hot-potato it out 
> a local transit connection?

Depends on the CDN, but its possible the traffic is coming from different 
locations and not all CDNs even have a network, so if you don't have 
peering with their location serving the traffic (and they don't have a 
network), the traffic will have to come to you via other paths.

> Are their transit costs so low that they don't care about using an IX 
> connection over transit unlike a small operator like me? Is this just a

Maybe.  Or maybe the traffic to you is small enough (to them) that you're 
not on their radar as a desirable peer.  Or maybe they just haven't gotten 
around to sending you a peering request yet.

> Secondly can someone explain to me why some CDNs want a gigabit or two 
> of traffic to be exchanged between our respective networks before they 
> would peer with me via a public IX?

Which ones want that much?  We like to see some traffic before moving from 
"IX route-server peering" to direct peering via the IX, just because there 
are so many possible peers and only so much router resources.  It's really 
not worth the resources (router or management) to direct peer with a 
network with which there's virtually no traffic being exchanged, just 
because we're on the same IX(s).  1-2G to peer seems kind of high.  Some 
might insist that you move peering to PNI if you're doing >1-2G across an 
IX.

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  Jon Lewis, MCP :)           |  I route
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