Traffic engineering and peering for CDNs

Mon Jun 6 17:53:12 UTC 2016

Some rely on performance testing to the client's DNS resolver and if they're not using on-net ones, they'll be directed to use a different CDN node. 

----- 
Mike Hammett 
Intelligent Computing Solutions 
http://www.ics-il.com 

Midwest Internet Exchange 
http://www.midwest-ix.com 

----- Original Message -----

From: "Graham Johnston" <johnstong at westmancom.com> 
To: "nanog at nanog.org" <nanog at nanog.org> 
Sent: Monday, June 6, 2016 8:36:43 AM 
Subject: Traffic engineering and peering for CDNs 

Lately I have been putting in some effort to maximize our IX connections by trying to work with the top 5-ish list of ASNs that still send us traffic via a paid transit connection despite the fact that we are both present on the same IX(s). In one case I missed the fact that one ASN wasn't using the IXs route-servers, that's on me for not spotting that one. 

Even with proper IX peering in place though it seems like some CDNs are better at using the IX connections than others. ASN 15169 for instance does an excellent job sending more than 99.99% of traffic via the IX connection; thank you. While others only seem to manage to send 60 - 80% of traffic via the IX. 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? 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 non-obvious issue wherein they maybe just can't originate enough of the traffic near the IX and therefore don't make use of the IX connection, again a hot-potato phenomenon? 

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? I totally get those kinds of thresholds before engaging in a private interconnect but I don't understand the reluctance with regard to a public IX, that they are already established at. Is it again just a simple case of bandwidth economics that operate at a different scale than I can comprehend? 

I'm hoping the community can shed some light on this for me as I'm trying to avoid grilling the operators that are working with me as I don't expect those front line individuals to necessarily have a full view of the factors at play. 

Thanks, 
Graham Johnston 
Network Planner 
Westman Communications Group 
204.717.2829 
johnstong at westmancom.com<mailto:johnstong at westmancom.com> 
P think green; don't print this email. 