Steps for verifying IP routing to a destination when not using policy-based routing

Verify a route to a particular destination IP address when you are not using policy-based routing (PBR).

About this task

Figure 1 shows the decisions involved for verifying IP routing to a destination.

Figure 1. Overview of verifying IP routing to a destination

Perform the following steps to verify IP routing to a destination:

1. Use the Ping command to determine whether there is connectivity to the identified IP address. For information about the Ping command, see z/OS Communications Server: IP System Administrator's Commands.
2. If the Ping command fails immediately, there might not be a route to the destination. Use the Netstat ROUTE/-r command to display routes to the network. Verify whether TCP/IP has a route to the destination. For information about the Netstat ROUTE/-r command, see z/OS Communications Server: IP System Administrator's Commands.

   If there is no route, proceed to step 3. If a route exists, proceed to step 4.

3. If there is no route to the destination, problem resolution depends on whether static or dynamic routing is being used. See z/OS Communications Server: IP Configuration Guide for more information about static and dynamic routing.
4. If a route exists, verify that the route is correct for the destination. If multipath routing is in effect for the destination, use the Ping command to determine whether there is connectivity to the IP address over any route. Invoke the Netstat CONFIG/-f command and check the value in the output report field, MultiPath, to determine whether multipath routing is in effect and what multipath routing is active.

   Determine whether there is a gateway identified for the route to the destination. If there is no gateway, then the destination address is presumed to be directly connected. In this case, proceed to step 5.

   If a gateway is identified for the route, use the Ping command to confirm connectivity to the gateway. Do one of the following:

   • If the gateway responds to a Ping, then there is a network problem at the gateway or beyond. Use the Traceroute command with the final destination address to determine at which hop in the route the failure is occurring. For information about using the Traceroute command, see z/OS Communications Server: IP System Administrator's Commands.
   • If the gateway does not respond to a Ping, proceed to step 5.
5. Determine which network interface is associated with the route to the destination. If the network interface operation has not been verified for this interface, verify it now. See Steps for verifying network interface operation for more information.
6. Use the DISPLAY TCPIP,,NETSTAT,ACCESS,NETWORK command to see whether network access control is enabled. If it is enabled, see Steps for verifying network access for more information.
7. Use the Netstat CONFIG/-f command to determine whether IP security is enabled. If the output report field, IpSecurity, contains the value Yes, then IP security is enabled. See Steps for verifying IP security and defensive filter operation for information about how to verify that IP security is correctly configured. If the problem still exists, see Documentation for the IBM Support Center to determine what problem documentation you need, and then call the IBM® Support Center.