TWT - Comcast congestion

Richard A Steenbergen ras at
Wed Dec 1 02:12:23 UTC 2010

On Tue, Nov 30, 2010 at 11:45:53AM -0800, Kevin Oberman wrote:
> We have seen the same thing with other carriers. As far as I can see, 
> Comcast is congested, at least at Equinix in San Jose. Since this is 
> all over private connections (at least in our case), the fabric is not 
> an issue.
> Maybe they will be using the money from Level(3) to increase capacity 
> on the peerings with the transit providers. (Or maybe not.)

I don't know about their connection to TWT, but Comcast has definitely 
been running their transits congested. The most obvious one from recent 
months is Tata, which appears to be massively congested for upwards of 
12 hours a day in some locations. Comcast has been forcing traffic from 
large networks who refuse to peer with them (e.g. Abovenet, NTT, Telia, 
XO, etc) to route via their congested Tata transit for a few months now, 
their Level3 transit is actually one of the last uncongested providers 
that they have.

The part that I find most interesting about this current debacle is how 
Comcast has managed to convince people that this is a peering dispute, 
when in reality Comcast and Level3 have never been peers of any kind. 
Comcast is a FULL TRANSIT CUSTOMER of Level3, not even a paid peer. This 
is no different than a Comcast customer refusing to pay their cable 
modem bill because Comcast "sent them too much traffic" (i.e. the 
traffic that they requested), and then demanding that Comcast pay them 
instead. Comcast is essentially abusing it's (in many cases captive) 
customers to extort other networks into paying them if they want 
uncongested access. This is the kind of action that virtually BEGS for 
government involvement, which will probably end badly for all networks.

If there is any doubt about any of this, you can pop on over to and look at the BGP communities Comcast is tagging on 
their Level3 transit service, preventing the routes from being exported 
to certain peers. For example, to my home cable modem:

Community: North_America Lclprf_100 Level3_Customer United_States 
Chicago2 EU_Suppress_to_Peers Suppress_to_AS174 Suppress_to_AS1239 
Suppress_to_AS1280 Suppress_to_AS1299 Suppress_to_AS1668 
Suppress_to_AS2828 Suppress_to_AS2914 Suppress_to_AS3257 
Suppress_to_AS3320 Suppress_to_AS3549 Suppress_to_AS3561 
Suppress_to_AS3786 Suppress_to_AS4637 Suppress_to_AS5511 
Suppress_to_AS6453 Suppress_to_AS6461 Suppress_to_AS6762 
Suppress_to_AS7018 Suppress_to_AS7132

Richard A Steenbergen <ras at>
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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