IST1903I
FAILURE OVER VRN vrnname TO CP partnername

Explanation

This message indicates the occurrence of a dial failure or a connection INOP for a connection over the named Virtual Routing Node (VRN) to the named partner node. This message will appear after either message IST590I (for a dial out failure) or IST1196I (for a connection INOP). IST1903I can appear as a single line message or as the first message in a message group. The description of the message group follows the example. 
IST1903I FAILURE OVER VRN vrnnameTO CP partnername
IST2050I THIS PATH WILL NOT BE SELECTED FOR UNRCHTIM = seconds SECONDS
[IST2186I THIS PATH WILL NOT BE SELECTED FOR UNRCHTIM SECONDS]
IST314I END
IST1903I
  • vrnname is the name of the VRN over which the failure occurred.
  • partnername is the CP name of the node adjacent to the VRN that was the endpoint of the failed dial or INOPed connection.
  • This message is an indication that the named partner node cannot be reached at this time using the connection network path across the named VRN. This connection network path might have been chosen for this connection because it had a lower weight than any alternate path available at one of the following times:
    • The time of this failing dial
    • The time of the dial that set up the existing connection
    • The time of a path switch to this connection network path for an existing RTP connection
  • If IST1903I is issued as a single line message, and this path still has the lowest weight of any available path to the partner node, any attempt to redial the partner node will continue to try the path over this particular VRN, which will probably result in failure until the underlying problem with this path is corrected.
IST2050I
  • seconds is the number of seconds that the partner node through this VRN (both identified in message IST1903I) is considered to be unreachable.
  • This message is issued on a network node. It is issued as part of a group with IST1903I when the unreachable time value on the UNRCHTIM start option is specified or the UNRCHTIM operand is specified on a PORT or GROUP definition statement that defines this VRN in an Enterprise Extender Extended Communications Adapter (XCA) major node.

    See the UNRCHTIM start option in z/OS Communications Server: SNA Resource Definition Reference for more information.

IST2186I

System action

Processing continues. When IST2050I is issued with IST1903I, the route to the unreachable partner node through the named Enterprise Extender VRN will not be considered for a session path until the unreachable time expires. If the unreachable time expires and this path still has the lowest weight of any available path to the partner node, the path over this particular Enterprise Extender VRN will be selected on the next attempt to redial the partner node, which might again result in failure if the underlying problem with the connection has not been corrected. That dial failure will cause the unreachable time to be set again to prevent selection of the path through this Enterprise Extender VRN to the unreachable partner node for the period of time specified for that Enterprise Extender VRN. This will continue until the problem with the connection path is corrected.

Operator response

If message IST2050I is included with message IST1903I, the connection path over the named Enterprise Extender VRN will remain unavailable for the number of seconds specified as the unreachable time for that VRN, to provide time for you to find and correct the source of the underlying problem. Issue the DISPLAY TOPO,LIST=UNRCHTIM command to display the unreachable partner information and use the output to help identify the location of the failure.

If message IST2186I is included with message IST1903I, the connection path over the named Enterprise Extender VRN will remain unavailable for the amount of time specified by the UNRCHTIM start option to provide time for you to find and correct the source of the underlying problem. The UNRCHTIM value depends on which version of z/OS® Communications Server is in use on the end node’s network node server (NNS). If z/OS Communications Server V1R6 or V1R7 is in use on the end node’s NNS, the value comes from the end node’s configuration (either the UNRCHTIM start option or the UNRCHTIM operand on the PORT or GROUP definition statement that defines the VRN). If z/OS Communications Server V1R8 or later is in use on the end node’s NNS, the value comes from the NNS’s configuration (either the UNRCHTIM start option or the UNRCHTIM operand on the PORT or GROUP definition statement that defines the VRN). Issue the DISPLAY TOPO,LIST=UNRCHTIM command on the NNS to display the unreachable partner information. This information includes the expiration time (the time at which the path will no longer be considered unreachable). This information can also be used to help identify the location of the failure.

If the problem has been corrected and the display of unreachable partner information indicates that there are paths through Enterprise Extender connection networks that will remain unavailable for some time, the you can issue the MODIFY TOPO,FUNCTION=CLRUNRCH command to clear the unreachable partner information to make that path available for route calculation again. If you are receiving the IST1903I message group repetitively, you can increase the value of the UNRCHTIM start option using the MODIFY VTAMOPTS command or change the value of the UNRCHTIM operand on the PORT or GROUP statement in the EE XCA major node in VTAMLST and then use the VARY ACT,ID=xca_major_node,UPDATE=ALL command to change the value dynamically. See UNRCHTIM start option in z/OS Communications Server: SNA Resource Definition Reference and Unreachable time (UNRCHTIM) considerations in z/OS Communications Server: SNA Operation for more information about UNRCHTIM.

If IST1903I is issued as a single line message, to avoid repeated failures, you can temporarily make the connection path over the named VRN unavailable until the source of the underlying problem is found and corrected.

First, if it is active, turn off the start option PSRETRY. Issue the MODIFY VTAMOPTS, PSRETRY=(0,0,0,0) command to prevent any existing RTPs that are successfully using the named VRN to reach their destination endpoints from path-switching to a less attractive route. Then take one of the following actions to make the named VRN unavailable:
  • Issue the MODIFY TOPO FUNCTION=QUIESCE, SCOPE=NETWORK command specifying the VRN named in IST1903I to remove the VRN from consideration by Topology in route calculations. Quiescing the VRN will make all paths through this VRN unavailable for all nodes connected to the connection network, not just the path identified in message IST1903I.
  • Issue the VARY INACT command for the local link to the VRN.
  • Increase the weight of this connection network path by issuing the MODIFY TGP command for the TGs to and from the VRN.

You might need to take the above actions (disabling PSRETRY and the single action chosen from the list above) from both this node and the partner node to successfully route around the connection network problem. When you have taken these actions, use established procedures to diagnose the underlying problem at both this node and the partner node to find and correct the problem.

When the problem has been corrected, reverse the actions taken above so the current connections and future connection attempts will be rerouted over the connection network path. Depending on which action was taken above, do one of the following things:
  • Issue the MODIFY TOPO FUNCTION=NORMAL, SCOPE=NETWORK command for the named VRN.
  • Reactivate the local link to the VRN.
  • Issue the MODIFY TGP command for the TGs to and from the VRN to decrease the weight of the connection network path.

You can re-enable PSRETRY. This will cause existing RTPs to periodically check for a lower weight path and switch to it if one is available.

System programmer response

None.

Routing code

2

Descriptor code

5

Parent topic: IST messages for VTAM network operators IST1600I – IST1999I