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Optimising MTU setting in PPPoE ADSL Connections
Authored by: davidkisley on Aug 26, '05 09:52:11AM

it is importatant to remember that not all adsl providers use ATM. Or at least will not in the future, so testing before and after is very important. i work for a large DSL provider, and our current network supports this, but our next generation nework will use gig e optical links to aggragate DSLAMS, which will have a different optimal MTU.

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Powerbook G4 1GHZ 15.1



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Optimising MTU setting in PPPoE ADSL Connections
Authored by: wontz on Aug 26, '05 11:41:46AM

I also work for an ISP. The transport between the modem and the DSLAM is always done using ATM cells. This true for ADSL, ADSL2 and ADSL2+ protocol.

It's true that many large ISPs also use ATM for backbone (we don't). But since ATM remains from the house to the Central Office, 1454 will remains a good value.



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Optimising MTU setting in PPPoE ADSL Connections
Authored by: cahaddras on Aug 26, '05 07:25:48PM

It doesn't really matter whether the ISP uses ATM or not on its own network. ATM is used on the ADSL link regardless, otherwise it wouldn't be ADSL. However it's certainly true that there are variants on how PPPoE is carried over ADSL. For example, LLC/SNAP may be used instead of VCMux for carrying the ethernet packet over the ATM Virtual Connection, adding a further 8 or 12 bytes to the packet. So the optimal MTU may be different and it is worth experimenting.



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