PH62990: ALLOW STANDALONE DB2 SUBSYSTEM LOCATION ALIASES BE BOUND TO A DIFFERENT IP ADDRESS.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Allow standalone Db2 subsystem location aliases be bound to a
  different IP address.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All Distributed Data Facility (DDF) users.   *
  *                 Especially those that utilize the TCPIP      *
  *                 profile PORT statement BIND specification    *
  *                 (also known as BINDSPECIFIC method) to       *
  *                 define the IP address of a Db2 subsystem     *
  *                 that is not a member of a data sharing       *
  *                 group.                                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: IP address/port listen missing for      *
  *                      connectivity to a standalone Db2        *
  *                      subsystem.                              *
  ****************************************************************
  * RECOMMENDATION: Apply corrective PTF when available          *
  ****************************************************************
  When a standalone Db2 subsystem is started, the IP address
  for the Db2 subsystem is determined in the following ways:
  - Db2 uses the IPV4 or IPV6 specification in the BSDS
  - Db2 probes the TCP/IP stack to obtain the primary
    interface home IP address of the stack
  - Db2 learns its IP address from TCP/IP when it detects that
    the main PORT specification within the TCPIP profile PORT
    statement (a specification outside of Db2) has a BIND IP
    address specification
  
  When Db2 has no IPV4 or IPV6 specification in the BSDS and
  before it probes the TCP/IP stack, Db2 creates its listen
  socket and then binds this socket to INADDR_ANY. When the
  bind is successful, Db2 probes the stack to determine if the
  socket is still bound to INADDR_ANY. When Db2 learns that
  the MAIN port listen socket is not bound to INADDR_ANY,
  Db2 saves the returned IP address from TCP/IP as being the
  IP address of this standalone Db2 subsystem. Db2 displays
  its learned IP address in the DSNL085I message line of the
  output from the -DISPLAY DDF command. Db2 only tracks this
  single IP address. When the listen sockets for its main PORT
  and/or SECPORT are created and bound to the learned IP
  address, Db2 then activates any static or dynamic location
  aliases.
  
  During the activation of a location alias in a standalone
  Db2 subsystem where Db2 has learned its IP address from
  TCP/IP due to a PORT profile statement specification, Db2
  will then create a single alias port and/or alias secure
  port listen socket bound to its learned IP address.
  
  However, a recent Db2 APAR corrected an unintended situation
  where Db2 incorrectly created two different listen sockets
  for an alias port and/or secure port for a standalone Db2
  subsystem.
  
  Specifically, Db2 was incorrectly creating a second listen
  socket bound to INADDR_ANY. When the bind of a socket was
  received by TCP/IP and the bind IP address was INADDR_ANY,
  TCP/IP then used all parts of the port specification in the
  TCPIP profile PORT statement, including the BIND
  specification IP address by creating the IP address (unknown
  to Db2) and binding the alias port listen socket to this
  address. Db2 did not probe TCP/IP to determine if the alias
  port listen socket was still bound to INADDR_ANY.
  
  Before the unintended Db2 behavior was corrected, some
  customers were using it to create two different listen
  sockets for an alias port, especially when the alias port
  had a specification in the TCPIP profile PORT statement
  with a BIND IP address specification different than the
  main PORT specified for Db2. The result was two different
  listen sockets for the alias port, one correctly bound to
  Db2's learned IP address and a second incorrectly bound to
  the BIND IP address specification in the TCP/IP PORT profile
  statement for the alias port.
  
  With the recent correction, only the alias port listen
  socket bound to the learned IP address of the Db2
  subsystem is created, and the "secondary socket" is
  NOT created.
  

Problem conclusion

• When a standalone Db2 subsystem is started, Db2 has been
  changed to create its single listen socket for a location
  alias port or secure-port by requesting the socket be bound
  to INADDR_ANY. When the alias port specification in the
  TCPIP profile PORT statement includes a BIND IP address
  specification, the listen socket will be bound to the
  specified IP address. Normally, the BIND IP address
  specification should be the same as was specified for the
  main PORT of Db2. However, if the BIND IP address
  specification was different than was specified for the main
  PORT, the alias listen socket will be created bound to the
  BIND IP address specification and then the alias listen
  socket can then only be reached by targeting the alias
  port via its BIND IP address.
  

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:

  UI98541 UI98542

Modules/Macros

• DSNLILNR
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI98541

     UP24/10/02 P F410

• RD10 PSY UI98542

     UP24/10/02 P F410

Fix is available

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