PQ60599: RIP2/OSPF MULTICAST ADDRS NOT JOINED TO MEMBERSHIP GROUP FOR DYNAMICXCF LINKS RESULTING IN PACKET AND ADJACENCY LOSSES

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APAR status

• Closed as unreproducible.

Error description

• If using OMPROUTE with multiple dynamic XCF interfaces with
  identical IP addresses, potential packet and adjacency losses
  can occur when using RIP2 or OSPF multicasts. In order for TCPIP
  to receive inbound multicasts from routers, TCPIP must have
  registered multicast addresses in the membership group table.
  Depending on the protocol used, one of the three multicast
  addresses (224.0.0.9 for RIP2, 224.0.0.5 for all SPF, 224.0.0.6
  for all DRs) must be joined to the membership table by OMPROUTE
  for each active multicast-capable interface.  There is a problem
  in OMPROUTE where a multicast address did not get registered or
  one that got inadvertently deleted after deregistration.  These
  problems were addressed by development fixes in R120 (z/OS V1R2)
  which need to be routed to R50A (CS/390 V2R10) to ensure that
  multicast addresses for Dynamic XCF interfaces are joined or
  dropped properly; otherwise, OMPROUTE will not be able to
  receive multicasts necessary to maintain adjacencies (HELLOs)
  in the case of OSPF or receive RIP2 updates in the case of RIP2.
  Summary of the development fixes are as follows:
  1. MV22774: OSPF NEIGHBOR ACROSS SOME XCF LINKS NOT ESTABLISHED
     Code was modified to allow OMPROUTE to join the multicast
     group multiple times.  The problem was that OMPROUTE was only
     joining the multicast group for the first XCF interface or
     connection that came up the first time but not on subsequent
     ones.
  2. MV23917: OSPF ADJACENCY LOSSES WITH INTERFACES HAVING
     IDENTICAL IP ADDRESSES
     Code was modified to only drop multicast membership for an IP
     address when the last interface or connection was deleted or
     or stopped.  The problem was that OMPROUTE was dropping
     multicast group memberships on all interfaces with the same
     IP address when only one interface or connection was deleted
     or stopped.
  

Local fix

• A recycle of OMPROUTE may rectify the problem so that multicast
  addresses will be joined to the active dynamic XCF interfaces
  the first time.  However, any subsequent ones will not be added
  for dynamic XCF interfaces that became activated later.
  KEYWORDS: OMPROUTE MULTICAST OSPF RIP2 RIPV2 IGMP DYNAMICXCF XCF
            JOIN ADD DROP H390MCAS INMCREG INMCDEL
  SYMPTOMS:
  RIPv2: Missing RIP routes or route timeouts due to no RIP2
         multicasts received
  OSPF: Messages EZZ7919I and EZZ7921I indicate changes to events
        10 (1Way-Received) or 12 (Inactivity Timer for no
        multicasted HELLOs seen)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for OS/390 Release 10 IP: OMPROUTE           *
  ****************************************************************
  * PROBLEM DESCRIPTION: Dynamic XCF links lose adjacency        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When using several interfaces with the same IP address such as
  in a dynamic XCF environment, OMPROUTE may lose adjacency when
  one interface is stopped.  The multicast groups are updated for
  each ip address instead of just the last one.
  +-------------------------------------------------------------+
  + 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

Temporary fix

Comments

• The OMPROUTE multicast membership code has been updated for
  multiple interfaces using the same IP address.
  

APAR Information

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

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

  UQ66582

Modules/Macros

• EZAORRTP HHHINTBL H390MCAS OMPROUTE
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R50A PSY UQ66582

     UP02/06/12 P F206

Fix is available

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