Re: Can't set lower MTU on gif?

[Lloyd Parkes <lloyd%must-have-coffee.gen.nz@localhost>]

> On 19/06/2016, at 11:13 AM, John Klos <john%ziaspace.com@localhost> wrote:
> 
> I'd like to use gif to route IPv4 over IPv6. I set up gif0 on a NetBSD 7 machine like so via /etc/ifconfig.gif0:
> ...
> However, any packets larger than 1200 bytes or so don't get passed. In FreeBSD's man page for gif(4), this is mentioned:

I did a bit of testing and I suspect that one or both ends have an IPv6 interface with an MTU set to 1280 and something on the internet between them is interfering with ICMP. This will be the actual, real interfaces, not the gif ones. Try increasing the MTU on that interface from 1280 to 1320 or more (the reverse of the reduction mentioned on the manual page).

Cheers,
Lloyd