[c-nsp] MTU - PPPOE

[Mark Jones]

Its the overhead of the l2tp tunnel crammed into the limited frame size of
ethernet.  If you get an atm feed from bell you problem will disappear.

----- Original Message ----- 
From: "Paul Stewart" <pauls at nexicom.net>
To: <cisco-nsp at puck.nether.net>
Sent: Friday, July 15, 2005 9:00 AM
Subject: [c-nsp] MTU - PPPOE


> Here's an age old topic but with a twist....
>
> We provide DSL services to a number of customers (as a telco) and their 
> MTU
> must be 1492 in order for it to work properly.  This however is not true
> when we wholesale DSL from another telco (Bell Canada) which serves are
> largest DSL area.
>
> They (Bell) send us l2tp tunnels from their Juniper gear via a series of
> dot1q vlans which terminate on some Redback units (currently - but moving 
> to
> 7206VXR shortly).  With this arrangement we must use an MTU of 1452 at
> customer sites.
>
> My question is hopefully simple.. is there a way to provide service to 
> these
> customers with an MTU of 1492?  Seems like a simple question but I have a
> feeling it's complicated to resolve....
>
> Basically the layout is:
>
> Bell Demarc --> Cisco 2924 --> OC-12 transport --> Cisco 6509 --> Redbacks
>
> MTU is 1500 along the entire route....
>
> Thanks,
>
> Paul
>
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