Verifying Reachability of All Hosts in an OSPF Network

Purpose

By using the traceroute tool on each loopback address in the network, verify that all hosts in the network are reachable from each Services Router.

Action

For each Services Router in the OSPF network:

1. In the J-Web interface, select Diagnose>Traceroute.
2. In the Host Name box, type the name of a host for which you want to verify reachability from the Services Router.
3. Click Start. Output appears on a separate page.

1 172.17.40.254 (172.17.40.254) 0.362 ms 0.284 ms 0.251 ms 
2 routera-fxp0.englab.mycompany.net (192.168.71.246) 0.251 ms 0.235 ms 0.200 ms 

What it Means

Each numbered row in the output indicates a router (“hop”) in the path to the host. The three time increments indicate the round-trip time (RTT) between the Services Router and the hop, for each traceroute packet. To ensure that the OSPF network is healthy, verify the following information:

• The final hop in the list is the host you want to reach.
• The number of expected hops to the host matches the number of hops in the traceroute output. The appearance of more hops than expected in the output indicates that a network segment is likely not reachable. In this case, verify the routes with the show ospf route command.

For information about show ospf route, see Verifying the Number of OSPF Routes.

See Also