tech-net: Re: can't raise in kernel pppoe0 with mtu

Subject: Re: can't raise in kernel pppoe0 with mtu > 1460
To: Alicia da Conceicao <alicia@engine.ca>
From: Masaru OKI <oki@NetBSD.org>
List: tech-net
Date: 03/22/2005 17:05:17

Alicia da Conceicao wrote:

> Greetings:
>
> For some reason, whenever I attempt to increase the MTU on my in kernel
> pppoe interface beyond 1460, it fails:
>
>         # ifconfig pppoe0 mtu 1460
>         *OKAY*
>         # ifconfig pppoe0 mtu 1461
>         ifconfig: SIOCSIFMTU: Invalid argument
>
> Note that pppoe0 is tried to physical ethernet interface fxp0, which
> itself has a MTU of 1500.

SIOCSIFMTU depends on peer's LCP MRU if pppoe is already connected.
--
Masaru OKI <oki@NetBSD.org>