PI62074: TCPIP TIMERS MAY NOT BE EXPIRING AT CORRECT INTERVALS RESULTING IN UNEXPECTED DELAYS IN TIMER-BASED ACTIVITIES

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• With TCPIP timers not expiring at the correct intervals, this
  can lead to potential delays in any of the timer-based
  activities such as TCP packet retransmissions, TCP keepalive
  packets, TCP delayed acknowledgements, Sysplex monitoring, etc.
  
  Possible symptoms seen:
  
  * Sysplex monitor timer
  
    EZZ9674E tcpip_proc SYSPLEX PROCESSING WAS NOT RESPONSIVE FOR
            AT LEAST timer_secs SECONDS
  
    If RECOVERY was specified on the SYSPLEXMONITOR parameter of
    the GLOBALCONFIG statement, and this TCPIP stack is not the
    only member of the TCPIP sysplex group, the TCPIP stack leaves
    the sysplex group, inactivates all DVIPAs, saves all of
    VIPADYNAMIC block definitions, and takes S4C5 abend dump:
  
    EZZ4215I TCP/IP ABEND - DUMPING
    IEA794I SVC DUMP HAS CAPTURED:
      DUMPID=xxx REQUESTED BY JOB (tcpip_proc)
      DUMP TITLE=tcpip_proc  VxRx: Job(tcpip_proc)
      EZBXFPDX(HIP6xxx mm.ddd)+00045A S4C5/77620405
      SRBP=tcpip_asid,S=tcpip_asid,H=tcpip_asid
    EZZ9676E SYSPLEX PROBLEM DETECTION CLEANUP HAS SUCCEEDED FOR
             tcpip_proc
  
  Dump analysis:
  
  * Sysplex monitor timer problem determination events
  
    EZBXFCVT: 1F0D0000
    +06BE  XFCVT_PD_EVENTS................. 01000000
  
    Only bit7 in byte0 x'01' flag is ON for XFCVT_PDCSUCC_EVENT
    for successful event and all other events (OMPROUTE, VTAM,
    CSM, XCF Routes, Sysplex abend, and XCF status update) are
    OFF to indicate no error events. That is:
  
    0123 4567
    1... ....   XFCVT_OMP_EVENT1      initial OMP unrsp msg
    .1.. ....   XFCVT_OMP_EVENT2      last OMP unrsp msg
    ..1. ....   XFCVT_VTAM_EVENT      VTAM unresponsive msg
    ...1 ....   XFCVT_CSM_EVENT       CSM critical msg
    .... 1...   XFCVT_XCFROUTE_EVENT  No XCF routes msg
    .... .1..   XFCVT_Retry_EVENT     Sysplex Abend msg
    .... ..1.   XFCVT_XCFSTAT_EVENT   XCF Status msg
    .... ...1   XFCVT_PDCSUCC_Event   PDC success event act
  
  * Sysplex monitor timer timestamps for the interval updates:
  
    +0650  XFCVT_VTAMDOWN_TIME............. 00000000  00000000
    +0658  XFCVT_OMPROUTEUP_TIME........... D0AECDFE  93EA5F86
    +0660  XFCVT_XCF_ROUTES_TIME........... D0AECDBB  9265DE85
    +0668  XFCVT_STAT_TIME................. D0AECDDC  B9F52100
    +0670  XFCVT_MONINTF_TIME.............. D0AECDBB  9265DE85
    +0678  XFCVT_DYNROUTE_TIME............. D0AECDBB  9265DE85
  
    VTAM Down Time     00:00:00.000000
    OMPROUTE Up Time   22:13:02.403237 <- OMPROUTE is active
    XCF Routes Time    22:11:52.142429 <- Last update 70 secs ago
    Status Update Time 22:12:26.907474 <- Last update 35 secs ago
    MonINTF Time       22:11:52.142429 <- Last update 70 secs ago
    DynROUTE Time      22:11:52.142429 <- Last update 70 secs ago
  
    22:13:02.57 EZZ9674E tcpip_proc SYSPLEX PROCESSING WAS NOT
                RESPONSIVE FOR AT LEAST 66 SECONDS
  
    The XCF status update timer interval should be 1/4 of the
    TIMERSECS value. In this case with "TIMERSECS 66" coded,
    the interval is roughly 16 seconds. If no timer updates were
    made to the XCF status at the intervals such that the delay
    has exceeded the TIMERSECS value, then EZZ9674E gets issued.
  
    The Status Update Time is when EZBXFPDX was scheduled the
    first time because EZBXFPDM had not run and updated the time
    stamp. The XCF Routes Time is how long ago it was when PDM
    last ran.
  

Local fix

• * For sysplex monitor timer problem:
  
    1) Specify NORECOVERY on the SYSPLEXMONITOR statement so that
       no further recovery actions are taken. That is, the TCPIP
       stack will remain in the sysplex group. When using this
       option, ensure that the TCPIP stack is healthy based on no
       error conditions from the NETSTAT and storage reports.
  
    2) If RECOVERY is specified on the SYSPLEXMONITOR statement,
       set up automation to monitor for the EZZ9674E/EZZ9676E
       messages and issue the VARY TCPIP,,SYSPLEX,JOINGROUP
       command to rejoin the TCPIP stack to the sysplex group.
       Ensure that the TCPIP stack is healthy based on no error
       conditions from the NETSTAT and storage reports.
  
  KEYWORDS:
  TCP TIMERS ABEND S4C5 EZBITTUB EZBXFPDX EZBXFPDM EZZ9674E
  SYSPLEX MONITOR XMIT RETRANSMIT KEEPALIVE DELAYACK ACK
  TIMERSECS
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of the IBM Communications Server                   *
  * for z/OS Version 2 Releases 1 and 2 IP                       *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * TCPIP timers expire past the specified interval              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply PTF                                                    *
  ****************************************************************
  The TCPIP timer set processing may incorrectly calculate the
  expiration time to a greater value than the requested delta.
  The calculation error only occurs when a timer is being set at
  the same time as the TCPIP clock management task is executing
  and the internal clock management table wraps.
  

Problem conclusion

• The timer set processing has been amended to take into account
  
  the wrapping of the internal clock management table.
  

Temporary fix

Comments

APAR Information

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

  PI62051

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

  UI38314 UI38315

Modules/Macros

• EZB2FCVT EZBXFINI EZBITTUB EZBXFPDM EZBTIGBL
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R210 PSY UI38314

     UP16/06/29 P F606

• R220 PSY UI38315

     UP16/06/29 P F606

Fix is available

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