Displaying subnets and their paths across a network

Use the $D SUBNET command to display the subnet connections defined to JES2. A subnet is any subset of a network identified to an installation by the eight-character ‘SUBNET' name on the JES2 NODE initialization statement. Generally, the nodes in a subnet are physically close and perform a similar function. If you have access to one node within a subnet, JES2 assumes you have access to them all.

You could enter a $D SUBNET(*) to display all the subnets within the network.

$HASP816       SUBNET (A)     N1,N2
$HASP816       SUBNET (B)     N3,N4
$HASP816       SUBNET (C)     N5,N6

JES2 shows each node on each subnet.

The $D SUBNET shows what nodes are located within a particular subnet. The $D PATH command provides the installation's view of the path to a particular node and the resistance level of that path. The resistance indicates how likely an installation is to use a path. In all instances, the path manager chooses the path of least resistance.

When the $D SUBNET command is used in conjunction with the $D PATH command, it provides a powerful diagnostic tool. To determine network connectivity to remote node 6, an operator enters a $D PATH(6) and receives the following console display:

$HASP231  PATH(N6)      STATUS=(through LINE 7),REST=20,
$HASP231                PATH=(N1,N2,N3...N4,N5...N6)

JES2 shows that LINE 7 is the conduit that connects local node 1 to target node 6. The resistance is 20 and the actual path travels from node N1 to N6. The comma between nodes indicate a direct path from one node to the other, while the ellipsis (...) indicates that N3 to N4 and N5 to N6 involve travel through subnets.

In complex network configurations, these commands can help users determine why a path link is not receiving information and how to resend jobs across a network to reduce processing bottlenecks. For more information about networking, refer to z/OS JES2 Initialization and Tuning Guide, SA32-0991.