The behavior you get with "show ip route 192.168.49.0" is normal. You shouldn't do it though unless you have a good reason to do so. This is why you need to use "ip ospf network point-to-point" to change the default behavior. Note that the default ospf network type for the loopback interface is "loopback", which causes this behavior. In most cases, you do not need more than a host addresz on the loopback interface. The fact that a /32 is used on a loopback interface is only common sense. But it does not seem to agree with Jeff Doyle's book, bottom of page 524.Ĭould anyone comment on these observations? If I think it through, I guess I am not surprised you don't want the RIDs changing too often. Even if I clear ip ospf 30 process, the adjacencies get reset, but it still keeps the old RID. If the RID is based on a loopback, say lo96 with address 192.168.96.1, then I destroy the lo96 interface and create a different one with a different address, the OSPF process does not even blink - it carries on being 192.168.96.1. Without the ip ospf network point-to-point in place, the route shows up on the adjacent router with no OSPF details: Route metric is 65, traffic share count is 1 Known via "ospf 20", distance 110, metric 65, type intra area With the ip ospf network point-to-point, the route shows up on an adjacent router, complete with its OSPF details: I don't understand why the choice of that command the words command does not seem to reflect what it actually does.Īlso, I am puzzled by the way show ip route n.n.n.n behaves on an adjacent router for such a loopback. To change this behavior, the command is ip ospf network point-to-point, then it gets advertised as /24. I can sort of see the logic to this: you might want to give all your routers host addresses in the same subnet. If you include a loopback interface in an OSPF process, it gets advertised as a stub host. In addition, check the subnet mask to ensure that a remote address has not been interpreted as a local address.Can someone explain to me the logic behind the way OSPF handles loopback interfaces? BTW, this is using 12.2(17a). If the remote routing tables are correct and contain a valid route back to the sending host, use the arp -a command to determine whether the correct address is listed in the ARP cache. Most often, it indicates that a route back to the sending host has failed, because the destination host, one of the intermediary routers, or the default gateway of the destination host does not recognize the route back to the sending host.Ĭheck the routing table of the destination host to determine whether it has a route to the sending host before checking the routing tables of the individual routers. This message may be the result of network congestion, failure of the ARP request, packet filtering, a routing error, or a silent discard. Indicates that no “Echo Reply” messages were received within the default time of one second. Sorry I don’t have time to research further, but Help in 2000 + Microsoft Knowledge Base should be able to provide the rest of what you need to do. I think you may have a packet filtering problem.
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