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NT4 slow, WIn2k fast - NetBios over TCPIP?

Firstly this happens on all machines in my environment (servers, desktops, multiple hardware types and configs)

When I copy a file across a WAN link (Cisco PIX VPN over DS3's) from a NT4,0 machine to a WIn2k or a NT4.0 the data transfer rate is very slow.  Doing the same test with the same files from W2k to W2k is dramatically faster (about 10 times faster)

From looking at sniffer tracers the file copy to or from NT4.0 machines show the protocol as NetBIOS over TCPIP, Win2k to Win2k just shows TCPIP.

We have tried changing the default MTU/RWIN settings in the registry but this only has a minor impact on performance.

So my question is

What do Win2k machine talk to one another so much master that NT4.0?

Any ideas?
1 Solution
The transfer is faster because they don't have the extra overhead of communicating using NetBIOS.  NetBIOS operates at OSI layer 5, so it relies on the lower layers to encapsulate it and transport it across routed networks.  Since Win2K communicates primarily using TCP/IP, it doesn't get slowed down encapsulationing / decapsulationing NetBIOS packets.
darrenburkeAuthor Commented:
should the performance difference be so different?  Was NT4.0 always that slow?

From mbruner's answer, I would guess that doing FTP across those same links would have the desired effect of increasing the performance on your NT machines.
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Yes, it has always been slow across routed networks using TCP/IP.  It has to be encapsulated, and "must expose the NetBIOS interdace and have a means of mapping each NetBIOS interface command to some sequence of their own native network frames and protocols" (see http://support.microsoft.com/default.aspx?scid=kb;en=us;Q128233 ).  All of this adds overhead to the use of the protocol.

NetBIOS works well in non-routed environments when used with NetBEUI or other lower-layer protocols that implement NBFP.  It is very fast.  However, once it has to be routed, then things get slower.

This is supposedly one of the major reasons why Microsoft is moving away from NetBIOS with Windows 2000 / XP.

And, yes, FTP would help, since it relies on TCP/IP only.
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My answer was close to correct.  Here is a link to Microsoft's answer and explanation to this problem:


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