On Thu, 6 Dec 2001, Richard Rauch wrote:

> > > One was net.inet.tcp.rfc1323, I don't remember the second one.
> > > Maybe net.inet.tcp.init_win, or net.inet.tcp.mss_ifmtu
> >
> > Right...
> >
> > Turning off timestamps (by disabling all rfc1323 extentions, or just
>  [...]
> > Telling your gateway to set its MSS based on the MTU of the specific
> > outgoing interface (mss_ifmtu=1), will mean it will use an MSS that should
> > (assuming the other side is behaving, and there isn't some smaller MTU
>  [...]
>
> mouse-pppoe sets an MTU of 1400 on the ppp0 interface.  Should I be able
> to safely lower the MTU (of my ethernet) while my network is live, if I'm
> careful/lucky?  (I assumed that I could, but when I tried the second
> machine that I lowered (my gateway) crashed to the extent that it wouldn't
> even respond to ping...)

mouse-pppoe sets it to 1400???  I don't know why its so low, pppoe adds 8
bytes of encapsulation, so thats an mtu of 1492 over ethernet (mtu 1500).

I think you should be able to adjust the MTU all you want (although I've
heard some drivers don't support it).  I've done it on my -current gateway
and client, but there might be a bug in NetBSD-1.5 or in the specific
ethernet driver you use.  Try just lowering the mtu on the route instead
of changing the actual interface.

Rick