II12449: TCP SOCKET CONNECTION STATE DESCRIPTION

APAR status

• Closed as canceled.

Error description

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  TCP Socket Connection State Description
  
  KEYWORDS: TCPIPINFO
  SYN-SENT SYN-RCVD FIN-WAIT-1 FIN-WAIT-2 TIME-WAIT CLOSE-WAIT
  LAST-ACK
  
  ACTIVE OPEN (local app. initates connection establishment):
        SYN OUT   SEQ 1480267197 ACK          0  STATE    SYN_SENT
     ACKSYN  IN   SEQ 2414265383 ACK 1480267198  STATE    SYN_SENT
        ACK OUT   SEQ 1480267198 ACK 2414265384  STATE ESTABLISHED
  
  PASSIVE OPEN (remote app. initates connection establishment):
                                                 STATE      LISTEN
        SYN  IN   SEQ    2817827 ACK          0  STATE    SYN_RCVD
     ACKSYN OUT   SEQ 2529238365 ACK    2817828  STATE    SYN_RCVD
        ACK  IN   SEQ    2817828 ACK 2529238366  STATE ESTABLISHED
  
  ACTIVE CLOSE (local app. initiates connection termination):
  ACKPSHFIN OUT   SEQ 1187839881 ACK  956151930  STATE  FIN_WAIT_1
        ACK  IN   SEQ  956151930 ACK 1187839882  STATE  FIN_WAIT_2
     ACKFIN  IN   SEQ  956151930 ACK 1187839882  STATE  FIN_WAIT_2
     ACKPSH OUT   SEQ 1187839882 ACK  956151931  STATE   TIME_WAIT
  
  PASSIVE CLOSE (remote app. initiates connection termination):
  ACKPSHFIN  IN   SEQ 3661816120 ACK 3656855726  STATE ESTABLISHED
        ACK OUT   SEQ 3656855726 ACK 3661816121  STATE  CLOSE_WAIT
  ACKPSHFIN OUT   SEQ 3656855726 ACK 3661816121  STATE    LAST_ACK
     ACKPSH  IN   SEQ 3661816121 ACK 3656855727  STATE      CLOSED
  
  Active Open Explanation:
  SYN_SENT:    The local application has issued a socket open
               call.  This results in a SYN packet flowing to the
               remote stack.  The local stack then waits for an
               ACKSYN packet.  The connection remains in SYN_SENT
               state when this packet is received.
  ESTABLISHED: Follows from SYN_SENT state when the local stack
               sends an acknowledgement for the received ACKSYN
               packet, completing the three-way handshake.  Both
               sides can now send and receive data.
  
  Passive Open Explanation:
  LISTEN:      Waiting for a connection request from the address
               and port listed in the Foreign Socket column of
               NETSTAT.
               - "HOSTA..*" means waiting for a connection
                 request from any port on host HOSTA.
               - "*..100" means waiting for a connection request
                 from port 100 on any host.
               - "*..*" means waiting for a connection request
                 from any port on any host.
  SYN_RCVD:    The remote application has issued a socket open
               call.  This results in a SYN packet flowing to
               the local stack.  When the SYN packet is received
               by the local stack, an ACKSYN is sent back to the
               remote application.  The connection remains in
               SYN_RCVD state when this packet is sent.
  ESTABLISHED: Follows from SYN_RCVD state when the local stack
               receives an acknowledgement for the sent ACKSYN
               packet, completing the three-way handshake.
               sides can now send and receive data.
  
  Active Close Explanation:
  FIN_WAIT_1:  Follows from ESTABLISHED state when the local
               application issues a socket close or shutdown.
               This results in a FIN packet flowing to the remote
               stack.  The local stack is now waiting for an
               acknowledgment of the FIN.
  FIN_WAIT_2:  Follows from FIN_WAIT_1 state when the local stack
               receives an acknowledgment for the FIN that was
               sent.  The acknowledgment number must be 1 greater
               than the sequence number of the sent FIN to cause
               the state transition.
  CLOSING:     Follows from FIN_WAIT_1 state when the local stack
               receives an acknowledgement for the FIN that was
               sent and the FIN flag is also set (simultaneous
               close).  The acknowledgment number must be 1
               greater than the sequence number of the sent FIN
               to cause the state transition.
  TIME_WAIT:   Follows from FIN_WAIT_2 state or CLOSING state
               when the local stack receives a FIN and sends an
               acknowledgement.  The acknowledgement number must
               be 1 greater than the sequence number of the
               received FIN to cause the state transition.
  CLOSED:      Follows from the TIME_WAIT state when 2MSL (twice
               the maximum segment lifetime) has passed (MSL =
               60 seconds).
  
  Passive Close Explanation:
  CLOSE_WAIT:  Follows from ESTABLISHED state when the remote
               application issues a socket close or shutdown.
               This results in a FIN packet flowing from the
               remote app.  The local stack must receive the FIN
               and acknowledge it.  The acknowledgement number
               must be 1 greater than the sequence number of the
               received FIN to cause the state transition.
  LAST_ACK:    Follows from CLOSE_WAIT state when the local
               application issues a socket close or shutdown.
               This results in a FIN packet flowing to the
               remote stack.
  CLOSED:      Follows from the LAST_ACK state when the local
               stack receives an acknowledgement for the sent
               FIN.  The acknowledgment number must be 1 greater
               than the sequence number of the sent FIN to cause
               the state transition.
  .
  NOTE: For z/OS Commserver hints and tips go to:
  http://www.ibm.com/software/network/commserver/support/
  

Local fix

Problem summary

Problem conclusion

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:

Fix information

Applicable component levels