Help me understand show IP protocols command

mallyg27

I'm doing a lab with packet tracer. I have three routers and I'm running OSPF over the network. Everything works fine and I can ping all the devices. My question is the about the show ip protocols command. The part that shows the routing information sources has three sources but the router is only connected to two routers, so how can it be receiving information from three sources? One of its sources is its own interface. Is this an error with packet tracer or am I not understanding something?

R1#sh ip protocols
Routing Protocol is "ospf 10"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 192.168.64.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
192.168.48.0 0.0.15.255 area 0
192.168.64.0 0.0.15.255 area 0
Routing Information Sources:
Gateway Distance Last Update
192.168.48.1 110 00:14:15
192.168.64.1 110 00:14:15
192.168.64.2 110 00:14:15
Distance: (default is 110)

NetworkVeteran

mallyg27 wrote: »

The part that shows the routing information sources has three sources but the router is only connected to two routers, so how can it be receiving information from three sources? One of its sources is its own interface. Is this an error with packet tracer or am I not understanding something?

Use "show ip ospf neighbors" if you want to see current neighbors.

"show ip protocols" displays all sources of information that "ospf 10" has used at some point or another to build its table. This includes the router itself, displayed as "192.168.64.1" in this particular IOS image or "(this router)" in other IOS images, as well as routers that have been down for hours. The output's fine and helpful, used for its intended purpose.

For example, today I was having trouble with a neighbor. "show ip ospf neighbor" simply told me it wasn't a neighbor, "debug ip ospf hello" told me it wasn't sending hellos anymore, but only "show ip protocol" told me when was the last time the neighbor had been talking friendly-like. Each particular command has its uses.

mallyg27

NetworkVeteran wrote: »

Use "show ip ospf neighbors" if you want to see current neighbors.

"show ip protocols" displays all sources of information that "ospf 10" has used at some point or another to build its table. This includes the router itself, displayed as "192.168.64.1" in this particular IOS image or "(this router)" in other IOS images, as well as routers that have been down for hours. The output's fine and helpful, used for its intended purpose.

For example, today I was having trouble with a neighbor. "show ip ospf neighbor" simply told me it wasn't a neighbor, "debug ip ospf hello" told me it wasn't sending hellos anymore, but only "show ip protocol" told me when was the last time the neighbor had been talking friendly-like. Each particular command has its uses.

If you say it can learn routes from itself, then why wouldn't the routers other serial interface be added to the router information sources. The interface 192.168.64.0 is a directly connected route and there are no other other networks off that side so it could not have possibly learned anything from that side. The other serial interface with is 192.168.48.2/24 I thought would be added since I have two other networks that were learned via 192.168.48.1.

NetworkVeteran

If you say it can learn routes from itself,

I don't just say so. Peek at "sh ip route" and you'll see "C" entries. Peek at the LSDB and you'll see at the very least a Router LSA that's self-originated. The router itself is a source of info for both its routing table and the area's LSDB.

why wouldn't the routers other serial interface be added to the router information sources.

It chose to mention 192.168.64.1 because that is the router-id. See the line, "Router ID 192.168.64.1"