I was going to only clean off my dry erase board for drawing out my topologies on the fly, and do a write erase on all routers for when I re-familiarized myself with OSPF, however like an IT nerd on a Friday night I decided to setup at least the NBMA routers R1 R2 and R3.

So I got those setup, which I tested NOT putting neighbor statements on the hub to confirm no routes propagated which of course didn’t, but after I turned on neighbors I saw neighbors forming and then they started flapping / I was getting flapping EIGRP links. I had completely forgot in an NBMA network you need to get on that serial interface and issue the “ip ospf priority 0” on the spokes so they do not participate in the DR / BDR election.

So I did that on the spoke interfaces, clear ip ospf proc all around, and adjacencies eventually formed after I think a minute is the hello timer – It took forever.

So I got frisky and setup the router 5 which I was finally able to find the correct cable and it came right up, configured it with lo5 interface advertising 5.5.5.5 network across the NBMA. Then I get even bolder and got on R4 and added that on there, which I know will require a virtual-link to get it’s loopback to propagate because any router without an interface in area 0 needs a virtual-link configured to a router with an interface in area 0.

So I threw the config in on both sides along with the ospf networks, not sweating it at all, but I’m not seeing either side freak out with errors after I configured the first side (as it always will start throwing tons of errors until you configure the other end). So I get on R3 also with no errors, and I’m sure I’ve got it right using “area 34 virtual-link 4.4.4.4” on R3 in router config and the same on R4 using 3.3.3.3, then I figured out my mistake.

I had not even plugged in the two Ethernet interfaces with a cable. After cabling together:

*Mar  1 13:37:46.633: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
R3#show ip ospf virtual-links
Virtual Link OSPF_VL0 to router 4.4.4.4 is down
Run as demand circuit
DoNotAge LSA allowed.
Transit area 34, Cost of using 65535
Transmit Delay is 1 sec, State DOWN,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
R3#
*Mar  1 13:38:30.137: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on FastEthernet0/1 from LOADING to FULL, Loading Done
R3#
*Mar  1 13:38:45.157: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on OSPF_VL0 from LOADING to FULL, Loading Done
R3#show ip ospf nei

Neighbor ID     Pri   State           Dead Time   Address         Interface
4.4.4.4           0   FULL/  –           –        172.12.34.4     OSPF_VL0
1.1.1.1           1   FULL/DR         00:01:57    172.12.123.1    Serial0/2
4.4.4.4           1   FULL/DR         00:00:39    172.12.34.4     FastEthernet0/1

So I decided I am officially too fried for any further labbing to be useful / stick in my brain, however I am now to a point where I can make some stub networks tomorrow, and setup redistribution for Sunday or possibly save it until Monday then I am back to where I left off with Route-Maps.

I think anything ACL or NAT related is my cryptonite, and I think it’s because that is half my day at work doing it on Firewalls, so my brain for some reason does not want to learn the CCNP way of doing things for some odd reason. The psyche is a strange thing.

Stubbies next tomorrow, going to wr mem now before I forget!

EDIT:
I didn’t see 5.5.5.5 on R4’s route table, and forgot that the last I remember area 15 it was an NSSA total stub, so I added the virtual-link command on R5 and this is the freak out message I mentioned earlier:

*Mar  1 13:13:28.169: %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 172.12.15.5, FastEthernet0/1

It will keep repeating that until I enter “area 15 virtual-link 5.5.5.5” on R1, as seen in this output:

R1(config-router)#
*Mar  1 13:16:29.983: %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual-link but not found from 172.12.15.5, FastEthernet0/1
R1(config-router)#area 15 virtual-link 5.5.5.5
R1(config-router)#
*Mar  1 13:16:39.310: %OSPF-5-ADJCHG: Process 1, Nbr 5.5.5.5 on OSPF_VL0 from LOADING to FULL, Loading Done

And now finally so I can live with myself knowing my lab is squared away:

R4#sh ip route ospf
(Route codes redacted)

Gateway of last resort is not set

1.0.0.0/32 is subnetted, 1 subnets
O IA     1.1.1.1 [110/66] via 172.12.34.3, 00:31:23, FastEthernet0/1
2.0.0.0/32 is subnetted, 1 subnets
O IA     2.2.2.2 [110/66] via 172.12.34.3, 00:31:23, FastEthernet0/1
3.0.0.0/32 is subnetted, 1 subnets
O IA     3.3.3.3 [110/2] via 172.12.34.3, 00:31:23, FastEthernet0/1
5.0.0.0/32 is subnetted, 1 subnets
O IA     5.5.5.5 [110/67] via 172.12.34.3, 00:01:40, FastEthernet0/1
172.12.0.0/16 is variably subnetted, 4 subnets, 2 masks
O IA     172.12.15.0/24 [110/66] via 172.12.34.3, 00:31:23, FastEthernet0/1
O        172.12.123.0/24 [110/65] via 172.12.34.3, 00:31:23, FastEthernet0/1

BAM! It took two virtual-links but R4 can now communicate with R5.

I am officially fried now, and must stop myself from labbing more, signing off now.