LI76847: LLC LINK FAILS DURING BONDED ETHERNET FAILOVER

Communications Server for Linux, Version 6.4 -- Latest Fixpack

APAR status

• Closed as program error.

Error description

• When using LLC protocol with a bonded ethernet adapter and the
  underlying primary adapter fails so the backup adapter takes
  over, a link station using this adapter will fail.
  

Local fix

• restart the link
  

Problem summary

• USERS AFFECTED: All users of LLC on s390x systems.
  
  PROBLEM DESCRIPTION:
  When using LLC protocol with a bonded ethernet adapter and the
  underlying primary adapter fails so the backup adapter takes
  over, a link station using this adapter will fail.
  
  PROBLEM SUMMARY:
  A previous fix, LI75483, dealt with a problem with re-ordering
  frames before processing by the LLC driver. This re-ordering is
  done by using an internal sequence numbering method implemented
  by zOS on the ethernet frames. This will not be visible on a
  packet trace.
  
  When the bonded ethernet failover occurs, the sequence numbering
  changes. This causes Communications Server to ignore any frames
  that would appear to be out of sequence, until the next expected
  sequence number frame is received.
  

Problem conclusion

• Code has been modified so that when a bonding failover occurs,
  the next sequence number received will be accepted as the new
  starting point. Also, the following message will be logged in
  /var/log/messages:
     SNA LLC2 Ethernet bonded port #xx failover.
  

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:

  LI77309

Fix information

• Fixed component name

  CS LINUX ON ZSE

• Fixed component ID

  5724I3400

Applicable component levels

• R640 PSY

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