[afnog] How to convince providers to take the sane option....

Andrew Alston Andrew.Alston at liquidtelecom.com
Tue May 13 15:18:45 UTC 2014


Hi All,

(Apologies if this come through twice, I believe I accidentally posted from an unsubscribed address earlier)

I’m in a little bit of a rant mode in this post and openly admit it, but I’m getting REALLY frustrated and hoping someone here might have some advise on how to convince providers to actually do what is sane rather than what hurts them and hurts everyone else in the industry.

So, to describe the problem.

Certain providers in East Africa are announcing aggregate routes to exchange fabrics and then announcing de-aggregate routes to their transit providers who are not on the exchanges, do not peer, and have all their traffic going internationally.

What happens in this scenario, the traffic never stays local, flows out internationally, switches through Europe and comes back on international links, increasing latency from what could be 3 or 4 milliseconds to an effective 300+ milliseconds.

In an even worse scenario, providers do this at exchanges where content engines such as GGC caches are hosted.  Those who are hosting the GGC caches and feeding the content to exchanges, then have the following happen:

The aggregates arrive via the exchange, get mapped onto the GGC’s, and the GGC’s attempt to send traffic back to the person announcing the aggregates.  Because the GGC host is carrying a full table on their routers, the routers then ignore the aggregates and use the de-aggregates and send the traffic out internationally and it comes back via Europe.  This entirely defeats the point of having localised content, drives up the costs and actually encourages the entity hosting the caches to stop feeding the content to the IXP in question.

Despite explaining the situation to the relevant providers, over and over again, and concretely demonstrating the negative effects of what they are doing, the only answer you get is “We aren’t changing, we do traffic control like that”

Now, that there is a solution, drop the entire AS number from the global table on the European transit ingress which will force the aggregates coming via the exchange to be used, but that seems to be a horrible solution, since an outage at the exchange then causes a complete blackhole to that ASN and drastically reduces redundancy.  But it seems also to be the only solution left when providers choose not to take the sensible option.

I’ve stood at many many AfriNIC and AFNOG events and heard us talk about keeping content on the continent local, its a song being sung constantly since 2005.  Now, we either want local content, or we want to continue to play routing games like the ones discussed above, but it cannot work both ways, the fundamentals of networking ensure this.  So as a last point, if anyone reading this is sending aggregates to an exchange and de-aggregates to their transit providers, please, this is one network engineer that is begging you to behaviour like a good net citizen and fix your routing!!!

Thanks

Andrew


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