Steinar H. Gunderson wrote:
> On Mon, Jul 23, 2007 at 06:13:42PM -0400, Chuck Lever wrote:
>> It would help if we could take a look at a clean network trace of the bad 
>> and the good mount operations.
> 
> It was quite simple to test this myself. I started the kernel server on a
> machine, then shut down portmap. First I did:
> 
>   fugl:~> sudo mount -t nfs -o port=2049,mountport=901,nfsvers=3 192.168.0.101:/ /mnt
>   mount: mount to NFS server '192.168.0.101' failed: System Error: Connection refused.
> 
> The dump is attached as "default.dump". Then I did
> 
>   fugl:~> sudo mount -t nfs -o port=2049,mountport=901,nfsvers=3,udp 192.168.0.101:/ /mnt 
> 
> which is attached as "udp.dump".
> 
> Note that in default.dump, UDP is simply never tried at all. I believe that
> to be a bug.

It looks like, in the UDP dump you sent, there is no attempt to contact 
the portmapper at all.  The mount request is the first thing in the 
dump, and the request goes right to the port specified on the command line.

The TCP case fails because mount.nfs is using the portmapper even though 
the user has specified the ports on the command line.  Could that be the 
root cause of the failure?