Re: [MiNT] Mintnet success ?

["Roger Burrows" <anodyne@cyberus.ca>]

On 14 Nov 2007 at 21:47, Peter Slegg wrote:

> On Wed, 14 Nov 2007 16:30:26 -0500, Mark Duckworth <mduckworth@atari-source.com> wrote:
> > The MTU of ethernet is 1500.  Under will definitely work fine, but you
> > will incur more overhead.  Sounds to me like you're ahead of the game
> > though seeing as how it's actually working.  I don't think this is
> > negotiable when it comes to setting it higher though :-P  The fact that
> > it's working indicates an undersized/corrupted buffer somewhere (or
> > perhaps a defect with the card).
> >
> > Thanks,
> > Mark
> >
> 
> I've tried several different drivers and 3 different cards so we
> can eliminate those possibilities.
> 
> Why does lo0 have mtu bigger than 1500 ?
> 
> lo0:    flags=0x4b<UP,BROADCAST,LOOPBACK,RUNNING>
>         inet 127.0.0.1 netmask 255.255.255.0 broadcast 127.0.0.255
>         metric 0 mtu 16384
> 

It's a loopback, i.e. no actual transmission, just moving output buffers to 
input buffers on the same system.

> Is 1500 a Mint limitation ? On a linux box I could ping packets
> much bigger than 1500
> 

The ethernet max packet size is 1500 octets.  If you ping larger than that:
a) IP on the sending box would need to fragment the ICMP (ping) message
b) IP on the receiving box would need to be able to reassemble the fragments

AFAIK, the largest MTU than you can always assume is allowed is still 576 
octets, although these days 1500 is (I think) pretty much assumed to be always 
possible.

Since you've tried different NICs, perhaps the problem is in the receiving box? 
Or in the hub/switch that you are using?  Have you tried another hub/switch?

As a network novice, I am willing to be corrected on any of the above 
statements :-).

Roger