7.3 Procedure for Troubleshooting

To isolate and resolve TCP/IP problems:

  1. To verify that IP is bound to the desired interfaces with the correct addresses and masks for your internetwork, to load TCPCON, then select Protocols > IP > IP Addresses.

    Use INETCFG to make any required corrections. (To load INETCFG, enter inetcfg at the server prompt.)

  2. To check the routing table for routes to the required network, enter LOAD TCPCON at the system console prompt to load TCPCON, select IP Routing Table > Proceed, then press Enter.

    If routes are missing, verify that the required routing protocols have been enabled and bound to the correct interfaces in INETCFG. Also verify that the routing protocol in use on an interface is correctly configured on other routers that are accessible through that interface.

  3. To verify that static routing is configured if other third-party routers that do not use RIP or OSPF are connected on the network, load INETCFG and then select Protocols > TCP/IP > LAN Static Routing.

  4. To verify that the IP Packet Forwarding statistic is set to Enabled, load INETCFG, then select Protocols > TCP/IP > IP Packet Forwarding.

    Use INETCFG to make any required corrections, then reinitialize the system.

  5. Use PING or TPING to test connectivity.

    Perform Step 1 through Step 4 on any routers that cannot be reached. Start with the router that is closest to the local node.

  6. Verify that all client software has the Default Router parameter configured to match the IP address of the network board inside the router that is connected to the local segment.

  7. Load TCPCON for the following IP statistics:

    • Local errors (memory error)

    • IP errors (unexpected protocol errors)

      Check the configuration of other IP nodes on the network. Reduce IP traffic or use a network analyzer to identify the source of invalid packets.

    • IP address errors (misdirected packets)

      Check the Address Translation tables on other IP nodes to determine the source of the errors.

    • Unknown protocol errors (unsupported IP clients)

      Load the required applications.

    • No route found (router failure)

      Check the configuration of the routing protocols.

  8. Load TCPCON for the following ICMP statistics:

    • Destination unreachable (network failure)

      Use a network analyzer to determine the unreachable destination. Check that the routers on the path to the destination advertise the route.

    • Time exceeded (network failure)

      Reduce the excessive delays by reducing the size of the internetwork or increasing the speed of WAN links.

    • Redirects (router failure)

      Check that all routers on the network are properly configured and are advertising routes. Verify that the correct Default Router is configured on the clients.

  9. To verify that all configuration options are set correctly, load INETCFG and then select View Configuration.