[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Comcast route server not reflecting their reality
- Subject: Comcast route server not reflecting their reality
- From: martijnschmidt at i3d.net (Martijn Schmidt)
- Date: Tue, 10 Sep 2019 16:42:10 +0000
- In-reply-to: <[email protected]>
- References: <[email protected]>
Unlike AS2914 which purely interconnects with AS7922, it seems that AS3356 also has direct interconnections to the various Comcast subsidiary networks which are hidden from the DFZ through no-export communities.. I figured this out due to a routing leak which happened a few years ago: https://dyn.com/blog/widespread-impact-caused-by-level-3-bgp-route-leak/
Give it a shot with the following list of communities - that should swing your traffic away from the AS3356 links: 65000:7922 65000:7015 65000:7016 65000:7725 65000:13367 65000:20214 65000:22909 65000:33287 65000:33490 65000:33491 65000:33650 65000:33651 65000:33652 65000:33657 65000:33659 65000:33660 65000:33662 65000:33667 65000:33668
From: NANOG <nanog-bounces at nanog.org> on behalf of Will Orton <will at loopfree.net>
Sent: 10 September 2019 01:06
To: nanog at nanog.org <nanog at nanog.org>
Subject: Comcast route server not reflecting their reality
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:
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...
-------------- next part --------------
An HTML attachment was scrubbed...