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How to show OSPF routes not in the Route Table
16 years 1 month ago #27649
by unlight
How to show OSPF routes not in the Route Table was created by unlight
Hello,
I am playing around with Dynamips to learn about OSPF. What I would like to do is show the OSPF routes advertised to a router from its neighbour which aren't in the routing table because a better path already exists (i.e. same subnet, different AD or metric).
I would like to be able to see the distance / metric for those routes.
I have tried to find my way through show ip ospf database * commands but I can't find the info anywhere. I know the route is there, because when I shut down the interface or change the bandwidth/cost the network converges and the previously unfavoured route is used.
Any help is most appreciated - thanks!
I am playing around with Dynamips to learn about OSPF. What I would like to do is show the OSPF routes advertised to a router from its neighbour which aren't in the routing table because a better path already exists (i.e. same subnet, different AD or metric).
I would like to be able to see the distance / metric for those routes.
I have tried to find my way through show ip ospf database * commands but I can't find the info anywhere. I know the route is there, because when I shut down the interface or change the bandwidth/cost the network converges and the previously unfavoured route is used.
Any help is most appreciated - thanks!
16 years 1 month ago #27651
by S0lo
Studying CCNP...
Ammar Muqaddas
Forum Moderator
www.firewall.cx
Replied by S0lo on topic Re: How to show OSPF routes not in the Route Table
Hello unlight,
OSPF is a link-state routing protocol. Routers don't actually advertize their routes to neighboring routers. Instead, they advertise the states of the links connected to them. At the end each router in the network gets a full topology map of the whole network (in a single area). The SPF algorithm is then used to compute the reachability of destinations. This information is used to update the routing table. This process can discover changes in the network topology caused by component failure or network growth.
To show more info about the link-states database try "show ospf database" instead of "show ip ospf database". Unfortunately, I personally find the details about this command a bit unclear.
Hope this helps.
OSPF is a link-state routing protocol. Routers don't actually advertize their routes to neighboring routers. Instead, they advertise the states of the links connected to them. At the end each router in the network gets a full topology map of the whole network (in a single area). The SPF algorithm is then used to compute the reachability of destinations. This information is used to update the routing table. This process can discover changes in the network topology caused by component failure or network growth.
To show more info about the link-states database try "show ospf database" instead of "show ip ospf database". Unfortunately, I personally find the details about this command a bit unclear.
Hope this helps.
Studying CCNP...
Ammar Muqaddas
Forum Moderator
www.firewall.cx
16 years 1 month ago #27676
by unlight
Replied by unlight on topic Re: How to show OSPF routes not in the Route Table
Yeah I was starting to suspect something similar when I couldn't find a straight forward solution (unlike EIGRP / BGP). If I setup a null route I see that route turn up under the 'Network LSAs' in show ip ospf database but there is no useful information. I think I need to read up a bit more. Cheers.
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