Comcast route server not reflecting their reality

Mon Sep 9 23:06:54 UTC 2019

I'm seeing odditiies when trying to traffic-engineering my way around an AS 3356-to-7922 performance issue.

I buy transit from 3356 and announce my /19 to 3356. I set traffic engineering community 65000:7922 to supress announcement of it from 3356 to 7922.
When I do that, at route-server.newyork.ny.ibone.comcast.net I see the AS-path for my /19 change from:
3356 <me>
to:
2914 <me>

which makes sense as I also have transit from 2914.

So that's great, 7922 should be routing to me via 2914 or, any path not via 3356.
But then if I go to a customer location on 7922's network, and traceroute to my /19, it still goes via 7922 3356 <me> !

Is 7922's looking glass no longer reflecting actual route selection in their network? Does Comcast do traffic engineering that is not otherwise reflected at their looking glass?

If I deaggregate my /19 and announce a /24 from it to 2914, I can draw the inbound traffic to me away from the 7922 3356 path. Which is not a real nice long-term solution...

-Will