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jfmezei
Premium
join:2007-01-03
Pointe-Claire, QC
kudos:23

1 edit
reply to sporkme

Re: Update on throttling issue...

>I'm just puzzled because if they do give you layer 2, how the
>hell are they actually examing the traffic at the ATM level?

PPPoE packets are broken up into multiple ATM packets to get through the ugly kludge that ADSL is. But at some point within the opaque Bell cloud, those PPPoE packets are re-assembled so that the BAS can look at the PPPoE header and route it to the right ISP.

From what I read, Bell is trying to re-assemble those packets back into ethernet packets as close to the DSLAM as possible. Once you get an ethernet frame with a full PPPoE packet inside, it becomes easier to look further inside to look inside the TCPIP packet and inside the TCPIP packet, you find the payload and decide if you like that type of data or not, and if you don't, you slow the packet down.

Once the packet is back into a single ethernet frame, it becomes easy for Bell to ship it to the ISP over WAN ethernet links instead of breaking it all up into silly ATM backs to be shipped to ISPs. (the conversion to ethernet as the link to ISPs is recent on Bell territory (I think it was done last year if I am not mistaken)