What is the Max MTU/MRT of EOIP over PPPoE connection ?

RouterOS General
1

I make a EOIP over PPPoE, there is a lot of packet loss.

I googled. This is a issue relate to MTU/MRU (Like VPN over PPPoE).

What is the Max MTU/MRU of EOIP ? Thank you !

2

If MTU of the physical interface is 1500 then

1500

  • 8 (pppoe+ppp header)
  • 28 (gre header)
  • 14 (eth header)
    =1450
3

How about the header size of IPIP tunnel ? Thx !

The maximum packet size in IPIP Tunnel is 1480 bytes, 20 bytes are overhead

Is this corrent ? Thx !

4

yep. so, in case of PPPoE, MTU will be 1500 - 8 - 20 = 1472

5

Dear Chupaka,
I have a RB1100AHx2 as concentrator PPPoE and a lot of tunnel EOIP over a big ospf network. Mikrotik set by default 1480 as MTU. Is it correct use 1480? If is not correct, how much must be and where must I change MTU, because on different message read different MTU. Where must I change the MTU, in pppoe server or on every EOIP interface?

Now pings, going from a simple ospf network to ospf + EOIP network + PPPoE concentrator, increase a lot and I don’t understand where I’m wrong.
Thanks in advance,
Carlo