Slow Performance over IBM Software Source Routing Bridge

The information in this article applies to:

• Microsoft Windows for Workgroups version 3.11

SYMPTOMS

Data transfers across a source routing bridge are very slow or appear to hang.

CAUSE

Windows for Workgroups (NetBEUI protocol) over a Token Ring Source Routing Bridge advertises a Largest Frame (LF) size of 8130 bytes. However, the Maxframe size is negotiated at 156 bytes. This causes very slow data transfer.

A network trace illustrates the problem:

   Destination   Source        Summary
   Server      WFWClient<00>   NETB D=2B S=16 Session initialize

   NETB: ----- NETBIOS Session Initialize -----
   NETB:
   NETB: Header length = 14, Data length = 0
   NETB: Delimiter = EFFF (NETBIOS)
   NETB: Command = 19
   NETB: Flags = 89
   NETB: 1... .... = NO.ACK ability

   NETB: .... 100. = Largest frame value = 4 <<<8130 bytes -IBM Spec

   NETB: .... ...1 = Version 2.0 or higher

   NETB: Max data receive size = 156     <<< Small Frame size negotiated.

   NETB: Transmit correlator = 0000
   NETB: Response correlator = 0016
   NETB: Remote session number = 43
   NETB: Local session number = 22

WORKAROUND

An updated NETBEUI.386 file is available to correct this problem. Replace your existing NETBEUI.386 file with the updated version. For information about how to obtain the updated driver, refer to the More Information section below.

The following options allow you to work around this problem:

• Use the real-mode NetBEUI protocol.

  -or-

• Execute "Net start Full" at the command prompt before running Windows for Workgroups.

  -or-

• Configure the bridge by changing a Largest Frame size (smaller or larger).

  In a case where an IBM software bridge is used to connect two 16 MB rings, it is not possible to change the LF size on the bridge software. In this case, you can bring down the network ring to 4 MB, or install a hardware bridge.

MORE INFORMATION

You can find NETBEUI.EXE (size: 38804 bytes) 
                        , a self-extracting file, on the following

• Microsoft's World Wide Web Site on the Internet

        On the www.microsoft.com home page, click the Support icon.
        Click Knowledge Base, and select the product.
        Enter kbfile NETBEUI.EXE (size: 38804 bytes) 
                                , and click GO!
        Open the article, and click the button to download the file.
  
  

• Internet (anonymous FTP)

        ftp ftp.microsoft.com
        Change to the Softlib/Mslfiles folder.
        Get NETBEUI.EXE (size: 38804 bytes) 
  

• Microsoft Download Service (MSDL)

        Dial (425) 936-6735 to connect to MSDL
        Download NETBEUI.EXE (size: 38804 bytes) 
  

   ARTICLE-ID: Q119591
   TITLE     : How to Obtain Microsoft Support Files from Online
               Services

STATUS

Some of the products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.