Re: PPPoE drops

[Damian Gerow <dgerow_(_at_)_afflictions_(_dot_)_org>]

Thus spake Jason McIntyre (jasonmcintyre_(_at_)_f2s_(_dot_)_com) [25/11/04 11:07]:
: > ``If your ISP has an FE crossover to Bell Canada, the optimal MTU is 1448.
: > This is because of all the tunnelling and packet overhead that's created
: > -- anything greater than 1448 (actually, it's 1452, but that's on on the
: > 8-byte boundary) will cause some sort of fragmentation in the packet between
: > you and your ISP.''
: > 
: 
: anyone know of other scenarios where 1492 does not work?

AFAIK, that's the only one.  And it's not that it doesn't work, but that you
run a much smaller risk of having your packets dropped (due to overloaded
hardware), and you go easier on everyone's equipment -- there's no
re-assembly required, so your network traffic uses considerably less CPU
power.

The key here is the FE crossover -- ISPs with ATM crosovers didn't seem to
be affected by this.

  - Damian