Problem solved: NetBSD was fine, Linux was fine - the second paket from 
a fragmented paket train did never make it from the NIC to the switch.
Adding a desktop hub between the NIC and the switch made all pakets
go through. No i wonder which hardware is broken: NIC or switch or
is it just out of tolerance ?

Frank

Frank Kardel wrote:
> Hi *,
> 
> i just set up an amd64 machine (ASUS K8V). Everything looked fine
> until some Linux boxes attempted to use that machine as
> NFS server.
> 
> The NFS-writes where stalled as the fragmented IP packets
> where not answered. Statistics show that fragmented packets
> are received and time out. 
...
> 
> Successful reassembly can be seen when a NetBSD 1.6ZK is the client.
> Linux does seem to trigger a reassembly inability in
> NetBSD 2.0C (20040411) on amd64. 
> 
> Any ideas ?
> 
> Frank