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JR52832: AFTER OUTAGE CP-CP SESSIONS RETRY TOO QUICKLY THEN GIVE UP

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APAR status

  • Closed as program error.

Error description

  • Communications Server for Windows
    ---------------------------------
    After a network outage, CP-CP sessions may retry too quickly
    and timeout before the mainframe is ready, then give up and not
    retry again once the mainframe is ready.
    

Local fix

  • Stop/restart the link station.
    

Problem summary

  • The cause of the problem is as follows:
    - CS has established CP-CP sessions with VTAM. For some reason
      these two sessions are carried over a pair of RTP pipes. This
      is not expected for EN-NN CP-CP sessions but will work in the
      protocol.
    - A problem in the network or at the mainframe causes CS to
      fail to send a packet on its ConWinner CP-CP session. The RTP
      pipe is marked as failed, and CS sends an UNBIND for the other
      CP-CP session in order to recycle these sessions on the other
      RTP pipe (which is still working okay).
    - VTAM sends a fresh BIND (our ConLoser session) on that pipe,
      which CS accepts.
    - CS sends a fresh ConWinner BIND on the same pipe (instead of
      creating a fresh pipe) since it has already timed out its
      ConWinner session.
    - VTAM believes the ConWinner session is still up (it has not
      yet timed out the first RTP pipe) and rejects the BIND with
      sense code 0805 indicating that session limits have been
      exceeded.
    - A bug in CS caused it to retry to establish the CP-CP sessions
      immediately five times before giving up.
    

Problem conclusion

  • CS has been corrected to introduce a timer that is backed off in
    this error case. Retries will occur after 5, then 10, then 15,
    then 20, then 25 seconds, for a total of 75 seconds.
    
    If VTAM still has not recovered after 75 seconds, then the retry
    code introduced with APAR JR49602 will take effect to ensure
    that CS will try to establish CP-CP sessions as soon as the
    mainframe has recovered.
    

Temporary fix

Comments

APAR Information

  • APAR number

    JR52832

  • Reported component name

    COMM SERV NT 6.

  • Reported component ID

    5639F2503

  • Reported release

    613

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2015-03-17

  • Closed date

    2015-07-08

  • Last modified date

    2015-07-08

Fix information

  • Fixed component name

    COMM SERV NT 6.

  • Fixed component ID

    5639F2503

Applicable component levels

[{"Business Unit":{"code":"BU029","label":"Software"},"Product":{"code":"SSHQNF","label":"Communications Server for Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"613"}]

Document Information

Modified date:
21 September 2023