difference with caching when connected to telia internet

Tore Anderson tore at fud.no
Sat Mar 18 11:09:05 UTC 2017

Hi Aaron,

> What happened was, when I turned up my new 10 gig Telia Internet
> connection a few days ago, I needed to balance out my (4) 10 gig
> internet connections so I chopped up a /17 into (4) /19's.  When I
> did this, I was still advertising the /17 to my local caches, but I
> was advertising the (4) /19's , one on each of my (4) 10 gig internet
> connections.  So the caches out on the public internet were learning
> more specific prefixes (longer masks) then my local caches were
> learning... so the caches on the internet were being used instead of
> my local caches.  Once google and Netflix tech support helped to make
> me aware of this, I correctly sent the additional (4) /19's to my
> caches and now all is well. 

Please instead advertise the /17 on all your Telia uplinks. You should
*additionally* advertise the four /19s to the different links, but make
sure to tag them with the NO_EXPORT community so they don't propagate
outside Telia.

That way you get the traffic engineering you want (i.e., load balancing
of ingress traffic from Telia), while at the same time avoiding coming
across as a self-serving jerk to everyone else on the Internet by not
polluting their routing tables/FIBs with four entirely superfluous /19s.


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