PH34372: EDGE LOAD BALANCER CRASH IN OS_XMITRAW6 FUNCTION

APAR status

• Closed as program error.

Error description

• ibmlb2 crashes.
  
  On Linux and Windows, server.log contains
  com.ibm.ws.loadbalancer.stack.LBStackException reports with
  'Communication with executor failed' message.
  

Local fix

• Use iptables to block icmp6 traffic which should keep it from
  crashing.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  IBM WebSphere Application Server Load       *
  *                  Balancer for IPv4 and IPv6                  *
  ****************************************************************
  * PROBLEM DESCRIPTION: The ibmlb2 process may crash in         *
  *                      function os_xmitraw6 when using IPv6    *
  *                      clusters.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The crash call stack shows os_xmitraw6 as the last LB
  function; lbsel_send and an lbicmpv6 function occur previously
  on the stack. The crash will not occur if only IPv4 clusters
  are defined.
  

Problem conclusion

• When the load balancer is sending an icmpv6 packet, a function
  was called with incorrect parameters which caused the crash.
  The code was modified to invoke the function with correct
  parameters.
  
  Fix levels:
     8.5.5.20
     9.0.5.8
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WS EDGE LB IPV4

• Fixed component ID

  5724H8812

Applicable component levels