

                           TECHNICAL BULLETIN
                             Bulletin #1-266

Date:  April 4, 1990

                              NetBIOS Patch

NetBIOS may hang under heavy network traffic conditions because of the
following:  An outbound packet is acknowledged while IPX is in the process
of sending that packet.  The acknowledge code attempts to cancel the
outbound packet and, if successful, sends the next outbound packet.  

Previous versions of NetBIOS incorrectly report a successful cancel in this
situation and then re-use the outbound packet's ECB to send the next
packet, with dire consequences.  This problem has been fixed in a patched
copy of NetBIOS.  This file is available on NetWire and is called
NB215C.ZIP.  

If you have the version of NetBIOS that came with NetWare v2.15, revision
C, you can patch the NetBIOS emulator yourself.  Listed below is the patch
for the NETBIOS.EXE file (the file is dated July 20, 1989 and contains
21,219 bytes).  The patch fixes this specific problem only.

   copy netbios.exe netbios.tmp
   debug netbios.tmp
   -e cs:0947 <CR>
   XXXX:0947  0A.0C <SPACE>           (you will need to enter the 0C and
                                      press the space bar)
   XXXX:0948  C0.FF <CR>              (you will need to enter the FF and
                                      then press the enter key)
   -e cs:1620 <CR>
   XXXX:1620  0A.0C <SPACE> C0.FF <CR>     (you will need to enter the 0C
                                           and press the space bar.  It
                                           will return with the C0.  You
                                           will enter the FF and press
                                           ENTER.)
   -w <CR> Writing XXXX bytes         (write the change)
   -q <CR>                            (quit)

If the stated values are not returned where indicated, do not proceed with
the patch.  Use the pre-patched copy of NetBIOS (available on NetWire).
