HFC MTU

[Coldplayer]

Hi guys, i'm on TPG HFC 100/20 and replaced my old TPG router which default was 1480 MTU. The new router I got has 1492 default. Wondering what I should set it to at? 1480,1492 or 1500?

Thanks

[adib_rahmang]

Hey @Coldplayer,

You can leave it on the default setting.

[Coldplayer]

C:\Windows\System32>ping 8.8.8.8 -f -l 1480

Pinging 8.8.8.8 with 1480 bytes of data:
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

When I set it at 1480 I get this, should I lower it?

[david64]

Hi @Coldplayer . Your ping command creates a request with data length set by l parameter. There is also an 8 byte ping request header and a 20 byte IP header. 

Max data length for 1 frame is 1452 bytes.  You can ping with longer data length but you have to allow fragmentation, i.e. no f parameter.

Normal internet traffic has IP header (20) plus TCP header (20) plus data. The router adds 8 byte PPPoE header.