Some of our subscribers are experiencing intermittent problems accessing certain sites - particularly Google, Hotmail and bank’s secured log-ons. I’ve read this might be a virus problem, but also possibly a problem with “MTU path discovery” which even the MT manual mentions in its usual obscure and mysterious way.
Most of our subscribers have an ethernet connection to their MT CPEs, a couple of wireless hops across MT routers to an x86 running RouterOS as gateway, which routes to two adsl modems. Internet traffic is routed from CPE to the gateway in L2TP tunnels. However on the backhauls I pass all Internet (ie L2TP) traffic through a PPPoE tunnel for accounting purposes, and I wonder if this is causing MTU problems, ie:
client computer to CPE > ethernet (1500) CPE to gateway > L2TP (1460) through PPPoE (1480) into PPPoA (?)
Given that a wireless frame can have an MTU of up to 2304 I wonder if it would help, and perhaps improve performance, if I increased the MTU of all the Mikrotik interfaces to >1500 so that every packet entering the system either from client computer from adsl modem with the ethernet MTU of 1500 will traverse the network without fragmentation, and perhaps help MTU path discovery, whatever it is.
Must now go and lie down - head hurts.