Debian :: Assign MTU Value For Network Interface?

I have dsl broadband shared through a Modem Bridge Mode forwarded to wireless router which is configured for dhcp lease to the clients(1 Desktop, 1 Laptop).

So, in My Debian Testing Desktop, I have following lines in /etc/network/interfaces :

Code:
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback

[Code]....