PK79822: LOSS OF DEFAULT ROUTE IN CINET PREROUTER TABLES

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A system is configured for multiple TCPIP stacks (CINET).  One
  (or more) of these stacks has multiple DEFAULT routes available
  as learned via dynamic routing.  If one of these routes is
  removed, the OMVS Prerouter will no longer indicate that a
  DEFAULT route is available over that stack (even though the
  other routes remain).  This condition will persist until another
  DEFAULT route is added to this stack.
  
  During this period, a NETSTAT ROUTE or OMPROUTE RTTABLE display
  will show the active DEFAULT routes.  However, a DISPLAY
  OMVS,CINET command will not show the DRS flag for this stack's
  entries.  Client applications attempting to connect to systems
  that require the default route will not get directed through
  this stack, but applications that have stack affinity set will
  not be affected.
  

Local fix

• Recycling one of the interfaces (VARY TCPIP,STOP followed by a
  VARY TCPIP,START) that has an active DEFAULT route will restore
  the DRS indication in the prerouter.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All z/OS Communication Server Version 1      *
  *                 Release 8,9,10 IP: CINET users with 2 or     *
  *                 more default routes per TCP/IP stack.        *
  ****************************************************************
  * PROBLEM DESCRIPTION: The default route supported (DRS) flag  *
  *                      is off in Unix System Services          *
  *                      prerouter while there is a default      *
  *                      route showing on the TCPIP stack.       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The default route support (DRS) flag is used by the Unix System
  Services prerouter to indicate that a stack in a Common Inet
  (CINET) supports a default route. There could be two or more
  default routes on the stack, but the prerouter only knows
  whether there is a default route support or not. The prerouter
  does not know the number of default routes defined on the stack.
  
  The problem is that the DRS flag is turned off on the prerouter
  while the stack shows there are default routes. If the stack
  says there is a default route, then the prerouter should show
  the DRS flag turned on.
  
  The sequence of events that lead to the DRS flag being off on
  the prerouter is:
  1. During a heavy system load, dynamic routing (OMPROUTE) was
     having a problem and messages, EZZ7921I OSPF Adjacency
     Failure, were issued.
  2. After the adjacency Failure messages were issued, the stack's
     default routes were all removed and Unix System Services
     prerouter was notified to turn the DRS flag off.
  3. Then immediately, new default routes via another interface
     (hipersockets) were added and the prerouter was notified
     to turn on the DRS flag.
  4. Within seconds, OMPROUTE recovered the adjacent routes and
     the original default routes were added back in to the stack
     and the prerouter was notified, the DRS flag is still on.
  5. However, after the original default routes were added the
     existing hipersocket default routes were removed from the
     stack routing table. Then the prerouter was notified
     and this caused the DRS flag to go off even though the
     original default routes were added back to the routing
     table.
  +-------------------------------------------------------------+
  + Please check our Communications Server for OS/390 homepages +
  + for common networking tips and fixes.  The URL for these    +
  + homepages can be found in Informational APAR II11334.       +
  +-------------------------------------------------------------+
  

Problem conclusion

• Modules IPV4RTE and IPV6RTE have been changed to notify z/OS
  Unix System Services only when the last default route is
  removed from the stack routing table.
  
  * Cross Reference between External and Internal Names
  

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:

  UK45387 UK45388 UK45389

Modules/Macros

• EZBIPPBR EZBIPRHD EZBIPRTE EZB6PRHD EZB6PRTE
  IPV4RTE  IPV6RTE
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1A0 PSY UK45387

     UP09/05/02 P F905

• R180 PSY UK45388

     UP09/05/02 P F905

• R190 PSY UK45389

     UP09/05/02 P F905

Fix is available

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