OPNsense Forum

Archive => 20.1 Legacy Series => Topic started by: hushcoden on July 20, 2020, 09:27:53 pm

Title: How to force MTU on PPPoE interface
Post by: hushcoden on July 20, 2020, 09:27:53 pm

I'd like to test MTU=1500 on my PPPoE interface, but if I enter the value on 'interfaces' -> 'wan' -> MTU and saving it doesn't actually change it (still 1492): is there a way perhaps through CLI to force the value to 1500?

Tia.

Title: Re: How to force MTU on PPPoE interface
Post by: Alphabet Soup on July 21, 2020, 01:54:15 pm

Haven't done it myself but this thread from when RFC 4638 support was added to OPNsense should give you something to try:  https://forum.opnsense.org/index.php?topic=2238.0 (https://forum.opnsense.org/index.php?topic=2238.0)

Title: Re: How to force MTU on PPPoE interface
Post by: franco on July 21, 2020, 04:01:03 pm

If I recall correctly you actually have to input the oversize MTU of 1508 to reach the 1500 MTU?


Cheers,
Franco

Title: Re: How to force MTU on PPPoE interface
Post by: franco on July 21, 2020, 04:11:23 pm

PS: Now I remember 8 byte is the PPPoE header that needs to be subtracted anyway ;)

Title: Re: How to force MTU on PPPoE interface
Post by: hushcoden on July 21, 2020, 04:59:18 pm

Thank you both, with 1508 it works  8)