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Title:DECnet/OSI for {ULTRIX,OSF/1}
Notice:Indicate version and platform when writing...see #2 for kits
Moderator:BULEAN::CARR
Created:Wed Sep 25 1991
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2187
Total number of notes:10469

2169.0. "LLC2 repeated enable/disable causes system crash" by EDSCLU::HILLMAN () Mon Apr 28 1997 19:25

Problem:  System crashes when repeatly enabling and disabling
LLC2 SAP and LLC2 SAP LINK.

A problem with system crashing when enabling and disabling LLC2
entities exists on DIGITAL UNIX V4.0, V4.0A, and V3.n operating
systems.  The following sequence of of commands, when repeated enough
times, will cause the node to crash.  Note that we have reproduced the
problem on various systems, with various versions of the operating
system.  The problem apparently is related to the LLC2 DECnet module,
as a system crash was predictably repeatable when using LLC2 entities
but could not be generated when using other entities (eg. SDLC).
Another interesting aspect of this apparently long standing LLC2
problem is the fact that we could not cause a system crash when the
same NCL commands were invoked via NCL prompts.  A crash could only be
generated when the commands were redirected to NCL (via file or command
line).

The following DECnet (and X.25) subsets are installed on Platinum systems
that crashed:
  
CTAANAL301 CTABASE301 DNABASE401 DNAKBIN401 DNANETMAN401 WDABASE300 WDADATALNKS300
WDADRIVERS300 ZZAUTIL301


The following shows the sequence of commands that causes the system crash.


Initial configuration:
----------------------

create node 0 llc2
create node 0 llc2 sap SNA-0
set node 0 llc2 sap SNA-0 -
        lan station = CSMA-CD station CSMACD-0, -
        local lsap address = 04
create node 0 llc2 sap SNA-0 link LINK-0
set node 0 llc2 sap SNA-0 link LINK-0 -
        acknowledge timer = 1000, -
        holdback timer = 500, -
        local receive window size = 127, -
        maximum data size = 8000, -
        remote lsap address = 04, -
        remote mac address = 10-00-5A-D4-AA-D3, -
        retry maximum = 10
create csma-cd
create csma-cd station CSMACD-0 communication port tu0
enable node 0 llc2 -
    sap SNA-0
enable node 0 llc2 -
    sap SNA-0 link *
enable csma-cd station CSMACD-0
                         

Commands (in file) that cause crash:
------------------------------------

ncl disable  LLC2 SAP SNA-0 Link LINK-0
sleep 3
ncl disable  LLC2 SAP SNA-0
sleep 3
ncl enable  LLC2 SAP SNA-0
sleep 3
ncl enable  LLC2 SAP SNA-0 Link LINK-0
sleep 3

When the above file is repeatedly executed the node will eventually crash.

The crash dump generated does not point to any DECnet modules.
A crash was also generated when using a Token Ring SAP instead of a 
CSMA-CD SAP.  (Apparently the cause of the crash is independent of a 
particular SAP.)
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