[c-nsp] What MTU for Bellsouth BBG / BRAS <-> LNS l2TP tunnel?

Jon Lewis jlewis at lewis.org
Wed Oct 27 20:40:16 EDT 2004

On Wed, 27 Oct 2004, Brian Feeny wrote:

> So you are running MTU 4470 on the PVC over which your L2TP session is
> built, but I am using 1500, and thats probably the difference.

Yes.  The ATM interface and L2TP carrying PVCs have the default (for ATM
DS3) MTU of 4470.  I haven't tried setting it to anything else to see if
other sized would work / break things.

> In the old days I use to think PPPoE was more ideal, because it could
> terminate on the customer desktop (WinPoet, etc).  But of course DSL is
> almost always terminated into CPE, so maybe I should look more closely
> at PPPoA vs. PPPoE.

PPPoE may have been nice back when DSL bridges were so popular, but since
pretty much all DSL CPE can do PPPoA now, may as well use that when

 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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