Hung NetBIOS connections?

[allancady]

I've started seeing intermittent problems with LAN access. I'm
wondering if anyone can help me out with this.

The setup is a set of seven server machines on a LAN inside a firewall.
It's a very static system, so we built it without a domain, no WINS,
just hard-coded machine names. Local networking is all using NetBIOS
over TCP/IP.

The problem I'm seeing now is, sometimes NetBIOS connections seem to
get hung. I don't understand the internal workings of NetBIOS well
enough to understand exactly what this means, but the symptom is, a
scheduled job that temporarily maps a network drive starts failing the
mapping (returns no drive letter). Once it fails, it seems to continue
to fail until I restart the machine.

The only tools I know of to diagnose this are NET USE and nbtstat. NET
USE shows no open connections. nbtstat -s shows the following:

Local Area Connection:
Node IpAddress: [192.168.0.4] Scope Id: []

NetBIOS Connection Table

Local Name State In/Out Remote Host Input Output
------------------------------------------------------------
JIM <00> Connected Out DAVE <20> 1GB 123MB
JIM <00> Connected Out BOB <20> 1GB 132MB
JIM <00> Connected Out GEORGE <20> 340MB 392MB

I'm guessing that it's those open connections that are getting in the
way of the drive mapping. But I don't know any way to flush them other
than rebooting.

Can anyone help me?

Thanks.

-Allan

 

[Robert L [MS-MVP]]

How many computers do you have in the LAN? I am thinking you may setup Domain network, perhaps WINS.

Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com
I've started seeing intermittent problems with LAN access. I'm
wondering if anyone can help me out with this.

The setup is a set of seven server machines on a LAN inside a firewall.
It's a very static system, so we built it without a domain, no WINS,
just hard-coded machine names. Local networking is all using NetBIOS
over TCP/IP.

The problem I'm seeing now is, sometimes NetBIOS connections seem to
get hung. I don't understand the internal workings of NetBIOS well
enough to understand exactly what this means, but the symptom is, a
scheduled job that temporarily maps a network drive starts failing the
mapping (returns no drive letter). Once it fails, it seems to continue
to fail until I restart the machine.

The only tools I know of to diagnose this are NET USE and nbtstat. NET
USE shows no open connections. nbtstat -s shows the following:

Local Area Connection:
Node IpAddress: [192.168.0.4] Scope Id: []

NetBIOS Connection Table

Local Name State In/Out Remote Host Input Output
------------------------------------------------------------
JIM <00> Connected Out DAVE <20> 1GB 123MB
JIM <00> Connected Out BOB <20> 1GB 132MB
JIM <00> Connected Out GEORGE <20> 340MB 392MB

I'm guessing that it's those open connections that are getting in the
way of the drive mapping. But I don't know any way to flush them other
than rebooting.

Can anyone help me?

Thanks.

-Allan

 

[Kurt]

NetBIOS over TCP/IP without a name server is legacy (even with a name server
is just for backward compatibility). It's always been flakey. But it sounds
llike a general connectivity issue. When the mapping fails, can you resolve
the name? i.e., from the run dialog can you \\computername? How about
\\IP-Address ? Can you ping? With all these server OS's, why not install
WINS? And if they're Windows 2000/2003 it all works SO much better with an
Active Directory and DNS.

....kurt

 

[allancady]

Thanks for replying.

When the mapping fails, can you resolve the name? i.e., from the run dialog can
you \\computername? How about \\IP-Address ? Can you ping?

Good questions. I went ahead and restarted all the machines last night
(needed to anyway to install latest Windows updates), so at the moment
I can't test it... I'll have to wait until the next time it fails.

With all these server OS's, why not install WINS?

We actually had WINS set up initially. After a little while, it just
seemed like one more component to maintain that wasn't really
accomplishing much (and a single point of failure), so I turned it off.
In two years, the machine configuration of the system hasn't changed
at all, so just leaving the names static seems like a reasonable way to
go. Most of the time it all works just fine.

And if they're Windows 2000/2003 it all works SO much better with an Active Directory and DNS.

I believe you there... I do get the impression that the setup we have
is pretty unconventional these days. But when I set it up, I was a
novice sysadmin (it's still not my forte), and I was trying to keep
everything as simple as possible. I had had one prior experience
trying to set up a domain controller that didn't go very well, so I was
trying to avoid that pain.

But the question I would like an answer to at the moment, that I still
don't have is, is there a way to flush those connections without
rebooting?

Thanks,

Allan

 

[allancady]

Well, lucky me, the job failed again last night AFTER I rebooted.

When the mapping fails, can you resolve the name? i.e., from the run dialog can you \\computername?
Yes.

How about \\IP-Address ?
Yes.

Can you ping?

Yes.

 

[John Wunderlich]

(e-mail address removed) wrote in

But the question I would like an answer to at the moment, that I
still don't have is, is there a way to flush those connections
without rebooting?

Right-click "My Computer"
Select "Manage"
Under "System Tools", open up "Shared Folders", select "Sessions"
Right-click in window, select "Disconnect all sessions".

HTH,
John