On 1/4/07, Ulrich Kunitz <[EMAIL PROTECTED]> wrote:

It looks like it is the SMB implementation in the kernel that is
dropping the connections. I've got a copy test running on CIFS and it
has done 5GB so far without out dropping the connection. From now on I
will remove SMB from my kernel and rely on the CIFS implementation.

Anyway the final product only uses sockets and no file server. Copy
commands are just an easy way to check the reliability of the link.

Thanks for the tips in helping me find this.

Next problem is figuring out why the link is running at half the speed
of Windows.

> Jon, I add to Daniel's mail some explanations. Network interfaces
> don't guarantee packet delivery. This is not a problem for TCP,
> because TCP will automatically retransmit packets not delivered to
> the other side. UDP doesn't have such mechanism and classical SMB
> is an UDP protocol, so the upper layer protocols need to handle

BTW, classical SMB is a connection oriented protocol that uses TCP
(originally NETBEUI). NFS is the one based on UDP. About 20 years ago
I designed about half of those SMB requests while working at
Microsoft.

> the retransmits. smbfs seems to have a very simple strategy
> retransmit the request after 30 seconds. This is far to long. Try

There is something broken in the protocol on one side or the other.
The stack should not be resorting to a 30 second time out. I captured
a TCP trace of the dropped session. It looks like the SMB request is
being sent to the server but the server never responds. TCP properly
delivered the request and acked it.So there is probably something
wrong with the format of the SMB request being made. That 30 second
pause behavior is caused by a software bug somewhere. This behavior
could also be from data corruption somewhere that SMBfs hits and CIFS
doesn't.

> CIFS as an alternative.
>
> Uli
>
> --
> Uli Kunitz
>


-- 
Jon Smirl
[EMAIL PROTECTED]

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