OA25881: EE HPR PIPE HANGS DUE TO MAX NLP SIZE ERROR WHEN ANR ROUTING THROUGH V1R9 VTAM.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• EE HPR pipe hangs (hung) when a V1R9 VTAM is used as an ANR
  node on the HPR pipe.  When the HPR pipe sets up, and different
  maximum packet sizes are defined for the links involved in the
  pipe - the resulting maximum NLP (Network Layer Packet) can
  be incorrect (as seen in IST1511I of a display of the pipe).
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All with multi-hop RTP pipes which ANR route *
  *                 through a V1R9 host using EE.                *
  ****************************************************************
  * PROBLEM DESCRIPTION: Multi-hop RTP pipe may transmit more    *
  *                      data than one of the hops supports.     *
  *                      Enterprise Extender must also           *
  *                      be involved in the configuration.       *
  *                      HPR traffic may get fragmented in the   *
  *                      IP network leading to firewalls         *
  *                      discarding the EE packets.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Sample Configuration:
  
  VTAM A    MTU 1400                MTU 1500      VTAM C
  APPL A =======EE======= VTAM B =======EE======= APPL C
  V1R8                    V1R9                    V1R8
  <--------------------CNR00005--------------------->
  
  1) APPL C initiates a sessions to APPL A.
  2) A multi-hop RTP pipe is setup with 2 APPN hops.  In this
     example, both APPN hops traverse EE connections.
  3) For this problem to occur:
     - An RTP pipee must ANR route through a node (VTAM B)
       that is at V1R9 or higher.  This ANR node (VTAM B)
       must also have at least one of its adjacent hops
       utilizing EE.
     - There must also be a variations in the maximum
       packet sizes which each link supports (which the
       RTP pipe traverses).  For an EE link, this is the MTU size.
       In this case, MTU values of 1400 and 1500 bytes are being
       used.
  4) When the RTP pipe is established from VTAM A to VTAM C,
     the maximum NLP size learned for each end of the pipe
     varies.  In this example, VTAM A displays the NLP size
     as 1469, while VTAM C displays it at 1369.
  5) Since the local link in VTAM A is 1400 bytes, HPR data
     sent to EE must be fragmented before it can be forwarded
     towards VTAM C.  In this case, UDP fragments are not
     permitted and some HPR packets are not delivered.
  6) The packets are reported as missing by VTAM C and
     the packets are retransmitted, fragmented and discarded
     over and over.
  7) All session utilizing this HPR pipe are hung.
  
  Note: If all nodes in this configuration are V1R9 or higher,
        this problem does not occur.
  

Problem conclusion

• ISTRCCRB - Subroutine NON_VR_CV80_BLD has been corrected to
             correctly set the maximum packet size to be the
             minimum of the received value and the value
             of the EE MTU (for the specific priority of the
             RTP pipe).  This processing takes place during
             RSETUP flows during the creation of an RTP pipe.
  ISTRPCRT,
  ISTAUCLA - Included for maintenance purposes.
  

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:

Modules/Macros

• ISTAUCLA ISTRCCRB ISTRPCRT
  

Fix information

• Fixed component name

  VTAM V4 MVS/ESA

• Fixed component ID

  569511701

Applicable component levels

• R1A0 PSY UA42540

     UP08/09/04 P F809 Ž

• R190 PSY UA42541

     UP08/09/04 P F809 Ž

Fix is available

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