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unexplainable IP Gateway's socket disconnect

How To


Summary

Unexplainable IP Gateway's socket disconnect. DUI430I UNSUCCESSFUL CALL TO BIND, ERRNO= 48
The ERRNO 48 indicates that the port is already in use.
Your TAMEL.xxxx statements in your CNMSTYLE member will define your startup pamrs for CNMTAMEL
. You can also view them by browsing the DUIFPMEM member. The default port is 4020.
However, I usually recommend that customer define another port number such as 14020 or
24020 because TCPIP often reserves or handles these low port numbers differently.
Could you check the PORT value with "LIST CNMTAMEL" or "BR DUIFPMEM" in NETVIEW. You could
run "NETSTAT CONN TCP TCPIP" in TSO to check if you could see anything using that PORT.
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Steps

some recommendations to config of the number of sockets follows to avoid the issues like termination connections, refuse connection when run out of sockets:

Plese see following formula and facts when NetView communicating over TCPIP, at least we need sockets:

  • 1 socket for listending for connection requests
  • 1 socket for each TCP (IPv4) connection the current NetView domain can make with another NetView domain (e.g: if the current domain is A,  then the first ‘RMTCMD SEND IP=’Address of B’ PORT=n DOMAIN=B’ requests that causes a connection to be started)
  • 1 socket for each TCP (IPv4) connection a remote NetView domain can make with current domain(e.g: remote domain B’s first RMTCMD SEND IP=’Address of A’ PORT=m DOMAIN=A request that causes a connection to be started)
  • 1 socket for each TCP6(IPv6) connection the current NetView domain(A) make connection to domain(B)
  • 1 socket for each TCP6(IPv6) connection that a remote NetView domain(B) make connection back to domain(A)

Note:

  1. If IPv6 not enabled, then we don’t need any additional estimation sockets for IPv6 connections.
  2. If tool like a port scanner make additional connections with NetView domain and eat up all available sockets then the DSIUDST task will terminates TCP/IP API which kills the connections. To avoid the same issue happens, then we recommended to add some additional sockets number depend on the requirements of tool like port scanner.
  3. And finally, it could be worth adding some fudge factor number of sockets (maybe some percentage of the total calculated above) that may leave some ‘idle room’ for the different workloads over IP connections.

Document Location

Worldwide

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Document Information

Modified date:
05 June 2023

UID

ibm17001263

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