OA39637: HPR PIPE HUNG WITH ONE SIDE NOT RESENDING PACKETS FOR A GAP REQUEST. 12/06/19 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• HPR pipe is hung. Trace shows the other end
  continually sending a GAP request to this VTAM but this VTAM is
  not resending the packets even though the data that would fill
  the gap is currently in the send queue. In most cases the packet
  will actually be in the wait for ack queue and not on the send
  queue.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of RTP connections.                *
  ****************************************************************
  * PROBLEM DESCRIPTION: HPR pipe is hung in RDRSP state         *
  *                      because the request for status is       *
  *                      not recognized as a new status          *
  *                      request.                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Consider this configuration:
       HOSTA---EE---HOSTB
  
  The problem may be summarized as follows:
  1. An RTP connection is established between HOSTA and HOSTB.
  2. NLPs from HOSTA arrive out of order at HOSTB
  3. HOSTB sends a status segment to HOSTA to report that
     there is a gap in the NLPs received.
  4. HOSTA retransmits the missing NLPs, but one is dropped again.
  5. HOSTB sends a status segment that is slightly different to
     HOSTA, but HOSTA does not interpret this status segment as
     new news, so it discards the status segment without
     attempting any retransmits.
  6. HOSTB and HOSTA get into a pattern of repeating this same
     sequence.
  7. When the HPR pipe is terminated, the termination
     will not complete due to the incorrect handling of the
     status segment and the HPR pipe will hang in RDRSP state.
     Additional symptoms may be a hung session.
  

Problem conclusion

• ISTRPCCS has been updated to handle status segments better.
  
  ISTRPNCB has been updated to define fields to keep track
  of the number of old statuses received consecutively.
  
  ISTTSEXT has been updated to define fields to keep track
  if any RTPs have had excessive number of consecutive old
  statuses
  
  ISTRPCRT has been included for maintenance purposes only.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UA65682 UA65683 UA65684

Modules/Macros

• ISTRPCCS ISTRPNCB ISTTSEXT
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R1B0 PSY UA65682

     UP12/07/14 P F207 «

• R1C0 PSY UA65683

     UP12/07/14 P F207 «

• R1D0 PSY UA65684

     UP12/07/14 P F207 «

Fix is available

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