MTU settings.

[eternityos at free.fr]

Hi everyone :)

Recently, we changed our internet connection to a ppp based (2Mbps).
So naturaly, I thought about changing the MTU of my interfaces on the FreeBSD
NAT router.
So I set it to 576 instead of the default, 1500 on the two interfaces, LAN and
WAN.
In what I have seen, 576 is the natural mtu for a ppp connection.

Right away after this change, the internet connection blocked. I only got it
back setting the mtu back at 1500.

Why did this block ?
Between the modem and the NAT router, we have a cisco router, I didn't change
it's mtu yet, would it be the cause ?

Any idea ?

Thank you.

Pierre Ancelot.