Ospf, dr, bdr

Hi guys,

I have been learning OSPF, and to understand it well, nothing is better than practice.

So I tried to set it up in GNS3.

Here is my topology (tell me if you can't read):

Everything works, I can ping any router from any router.
But there is still a point that I am missing:

I haven't added any loopback interface.

In my backbone (Area 0):
R3 is the DR and R4 the BDR. I don't understand why R3 is instead of R4 which has the same priority (1), but a higher ip address. (192.168.1.1 > 172.16.1.2).

Then I don't understand why R5 isn't a neighboring of R4.

Here are some conf:

[FONT=&quot]R4#sh ip ospf int[/FONT]
[FONT=&quot]FastEthernet0/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 172.16.1.1/29, Area 0[/FONT]
[FONT=&quot] Process ID 444, Router ID 192.168.1.1, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State BDR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 172.16.1.2, Interface address 172.16.1.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 192.168.1.1, Interface address 172.16.1.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:00[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 2/3, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 1, maximum is 1[/FONT]
[FONT=&quot] Last flood scan time is 4 msec, maximum is 4 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 172.16.1.2 (Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet0/1 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 10.0.1.1/29, Area 0[/FONT]
[FONT=&quot] Process ID 444, Router ID 192.168.1.1, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State DR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.1.1, Interface address 10.0.1.1[/FONT]
[FONT=&quot] No backup designated router on this network[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:05[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/1, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 0, maximum is 0[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 0 msec[/FONT]
[FONT=&quot] Neighbor Count is 0, Adjacent neighbor count is 0[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet1/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 192.168.1.1/29, Area 1[/FONT]
[FONT=&quot] Process ID 444, Router ID 192.168.1.1, Network Type BROADCAST, Cost: 1[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State BDR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.1.2, Interface address 192.168.1.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 192.168.1.1, Interface address 192.168.1.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:05[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/2, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 6, maximum is 6[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 0 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.1.2 (Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]R4#[/FONT]

Router R3

[FONT=&quot]R3>en[/FONT]
[FONT=&quot]R3#sh ip ospf int[/FONT]
[FONT=&quot]FastEthernet0/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 172.16.1.2/29, Area 0[/FONT]
[FONT=&quot] Process ID 333, Router ID 172.16.1.2, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State DR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 172.16.1.2, Interface address 172.16.1.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 192.168.1.1, Interface address 172.16.1.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:09[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 2/3, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 0, maximum is 3[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 0 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.1.1 (Backup Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet0/1 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 10.1.1.1/29, Area 0[/FONT]
[FONT=&quot] Process ID 333, Router ID 172.16.1.2, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State BDR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.3.1, Interface address 10.1.1.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 172.16.1.2, Interface address 10.1.1.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:04[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/2, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 1, maximum is 3[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 4 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.3.1 (Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet1/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 10.0.0.1/29, Area 2[/FONT]
[FONT=&quot] Process ID 333, Router ID 172.16.1.2, Network Type BROADCAST, Cost: 1[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State BDR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 172.18.0.1, Interface address 10.0.0.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 172.16.1.2, Interface address 10.0.0.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:04[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/1, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 8, maximum is 8[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 0 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 172.18.0.1 (Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]R3#[/FONT]

I don't get it. Am I missing something?
Any help would be welcomed!!

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Comments

Rakurai

Well, I am going to guess on the DR and DBR, and say that because the 192 address on R4 is in a different area ???

As for the neighbor not being established, make sure that the network is properly being advertised (SM/Area/Net ID). Try debugging on the routers and see what you see (debug ip ospf adj).

mattau

I think the key point to remember with ospf DR - BDR elections is this

for example

Say you boot up R3 first and it doesnt hear any other ospf routers competing for the election it will elect itself as the DR then when any other router on the segment comes online it WILL NOT influence the election like spanning tree does. meaning R3 will always still DR ( even if it had an ip address of 1.1.1.1) The only way you could have the election is to restart R3 and R4 (or clear ip ospf process) at the same time and then you will notice R4 being elected as DR.

also you have your topology in area 0 connected via broadcast fastethernet point to point style which means you will only have a DR and BDR per segement.

Ie - the segment to R3 - R4 will have a dr and bdr -
R3 to R5 will have its own DR BDR and R4 to R5 will have its own meaning 1 router can be all sorts of things. it can be a dr bdr or drother depending on whats connected.

also your problem as to why R4 wont become adjacent with R5 -

I would check your config on R5 and R4 and compare.

its most likely you havnt set something up correctly

remember they need to be in the same area, same hello dead timers, the interface must be open, same subnet. You should try a debug. the debugs are great they tell you what is going on (or wrong in the ospf process ) i find it to be very helpful.

Forsaken_GA

If your goal is to practice DR/BDR relationships and how they form, put a switch in the middle of area 0, and hook all of the routers into that, and address their interfaces in a common IP subnet, and then bring up OSPF. Then you have a valid need for DR/BDR elections (and if you do that, I'd add a 4th router to area 0 so you can see how the non DR/BDR routers form relationships with each other)

As far as your neighbor problem goes.... you post sh ip ospf int for R3 and R4, but not R5, and the adjacency problem is occuring on R5. Not much we can tell you. I'd suggest you run the same command on R5 and see what it has to say. I suspect you'll find that the interface connected to R4 isn't actually participating in OSPF (or it may not be up). This won't break your IP connectivity however, as R4 can still communicate with R5 through R3, it just makes your effective topology a line instead of a triangle

You'd be better off changing your Area 0 links to use point-to-point and get rid of the DR/BDR elections entirely, because that's basically how you have your topology designed. This would also free up a couple router ports. That may not seem like such a big deal when you're learning or labbing, but don't pick up bad design habits. Router ports are expensive in the real world. If you're going to do a full mesh in area 0, you need to know *why* you're doing it. Redundancy and Resiliency is the proper reason to do that, btw. Hooking everything into a switch means that if any one link breaks, you're cut off from the rest of it. Having each router linked to the other allows routing to continue even if any single link in area 0 goes down, which you've inadvertently demonstrated, due to R4 and R5 not forming a proper relationship.

bon_chan

Thanks for your replies.

Here is sh ip ospf int for R5:

[FONT=&quot]R5>en[/FONT]
[FONT=&quot]R5#sh ip ospf int[/FONT]
[FONT=&quot]FastEthernet0/1 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 10.1.1.2/29, Area 0[/FONT]
[FONT=&quot] Process ID 555, Router ID 192.168.3.1, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State DR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.3.1, Interface address 10.1.1.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 172.16.1.2, Interface address 10.1.1.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:08[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/1, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 0, maximum is 4[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 4 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 172.16.1.2 (Backup Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet1/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 192.168.3.1/29, Area 3[/FONT]
[FONT=&quot] Process ID 555, Router ID 192.168.3.1, Network Type BROADCAST, Cost: 1[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State BDR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.3.2, Interface address 192.168.3.2[/FONT]
[FONT=&quot] Backup Designated router (ID) 192.168.3.1, Interface address 192.168.3.1[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:08[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/2, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 7, maximum is 7[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 4 msec[/FONT]
[FONT=&quot] Neighbor Count is 1, Adjacent neighbor count is 1[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.3.2 (Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]

So Indeed, my bad. I didn't notice it first, but the interface f0/0 was not up.

Forsaken_GA wrote: »

If your goal is to practice DR/BDR relationships and how they form, put a switch in the middle of area 0, and hook all of the routers into that, and address their interfaces in a common IP subnet, and then bring up OSPF. Then you have a valid need for DR/BDR elections (and if you do that, I'd add a 4th router to area 0 so you can see how the non DR/BDR routers form relationships with each other)

OK then I will do that topology too.
I just read my book again:
An OSPF router will not form adjacencies to just any router. Instead, a client/server design is implemented in OSPF on each broadcast segment.

I realized that I missed the broadcast term. So I understand better your suggestion.

You'd be better off changing your Area 0 links to use point-to-point and get rid of the DR/BDR elections entirely, because that's basically how you have your topology designed. This would also free up a couple router ports. That may not seem like such a big deal when you're learning or labbing, but don't pick up bad design habits. Router ports are expensive in the real world. If you're going to do a full mesh in area 0, you need to know *why* you're doing it. Redundancy and Resiliency is the proper reason to do that, btw. Hooking everything into a switch means that if any one link breaks, you're cut off from the rest of it. Having each router linked to the other allows routing to continue even if any single link in area 0 goes down, which you've inadvertently demonstrated, due to R4 and R5 not forming a proper relationship.

Sorry (english is not my first language), but I am not sure to get what you are trying to say. Are you telling me to change my links (using serial instead of fastethernet)? So You mean that I should use only 2 routers? :confused
Is that why it should free up some router ports?

Forsaken_GA

bon_chan wrote: »

Sorry (english is not my first language), but I am not sure to get what you are trying to say. Are you telling me to change my links (using serial instead of fastethernet)? So You mean that I should use only 2 routers? :confused
Is that why it should free up some router ports?

No, you should change the network type on each link. Do some mmore studying/research on the different OSPF network types, what the difference between them is, and what different interface types default to as far as them.

And I think I might have put my mention of saving router ports in the wrong location. If you put a switch in the middle to create a true broadcast environment in area 0, then you wouldn't need a full mesh of links between the individual routers, you could establish all of your relationships with one link in area 0 per router. However, as I mentioned, that can impair resiliency in the network.

What I'm getting at is that your area 0 design is, in my opinion, actually correct, but given your confusion over the nature of DR/BDR elections, your don't know why it's correct, and I don't give credit for accidental answers hehe

bon_chan

Forsaken_GA wrote: »

No, you should change the network type on each link. Do some mmore studying/research on the different OSPF network types, what the difference between them is, and what different interface types default to as far as them.

And I think I might have put my mention of saving router ports in the wrong location. If you put a switch in the middle to create a true broadcast environment in area 0, then you wouldn't need a full mesh of links between the individual routers, you could establish all of your relationships with one link in area 0 per router. However, as I mentioned, that can impair resiliency in the network.

What I'm getting at is that your area 0 design is, in my opinion, actually correct, but given your confusion over the nature of DR/BDR elections, your don't know why it's correct, and I don't give credit for accidental answers hehe

Ok I clearly see what you mean.

bon_chan

So I have finally tried the following topology :

The DR is R3, and BDR is R2.
Everything works well!!

Then I cut R2 link and as expected R1 became BDR.

After that I put back R2's link and added a fourth router (R4).

And then R4 became DR and R3 BDR.
But I thought that no changes occur even if a new router has a higher address. Normally R3 should still be DR, shouldn't it?

I run a debug ip ospf event on R4 (while I was adding it to the switch):
[FONT=&quot]*Mar 1 00:04:41.027: OSPF: Send hello to 224.0.0.5 area 4 on FastEthernet0/1 from 172.14.0.1[/FONT]
[FONT=&quot]*Mar 1 00:04:46.355: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:04:51.027: OSPF: Send hello to 224.0.0.5 area 4 on FastEthernet0/1 from 172.14.0.1[/FONT]
[FONT=&quot]*Mar 1 00:04:56.355: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:01.027: OSPF: Send hello to 224.0.0.5 area 4 on FastEthernet0/1 from 172.14.0.1[/FONT]
[FONT=&quot]*Mar 1 00:05:06.355: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:11.027: OSPF: Send hello to 224.0.0.5 area 4 on FastEthernet0/1 from 172.14.0.1[/FONT]
[FONT=&quot]*Mar 1 00:05:14.515: OSPF: Rcv hello from 192.168.1.1 area 0 from FastEthernet0/0 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:14.515: OSPF: Send immediate hello to nbr 192.168.1.1, src address 192.168.1.1, on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:14.519: OSPF: Send hello to 192.168.1.1 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:14.519: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:15.799: OSPF: Rcv hello from 192.168.1.2 area 0 from FastEthernet0/0 192.168.1.2[/FONT]
[FONT=&quot]*Mar 1 00:05:15.799: OSPF: Send immediate hello to nbr 192.168.1.2, src address 192.168.1.2, on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:15.799: OSPF: Send hello to 192.168.1.2 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:15.803: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:16.259: OSPF: Rcv hello from 192.168.1.3 area 0 from FastEthernet0/0 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 00:05:16.259: OSPF: Send immediate hello to nbr 192.168.1.3, src address 192.168.1.3, on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.259: OSPF: Send hello to 192.168.1.3 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.259: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:16.355: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.419: OSPF: Rcv hello from 192.168.1.3 area 0 from FastEthernet0/0 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: OSPF: 2 Way Communication to 192.168.1.3 on FastEthernet0/0, state 2WAY[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: OSPF: Elect BDR 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.423: DR: 192.168.1.4 (Id) BDR: 192.168.1.3 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.427: OSPF: Send DBD to 192.168.1.3 on FastEthernet0/0 seq 0x15 opt 0x52 flag 0x7 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:16.427: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.427: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.427: OSPF: Elect BDR 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 00:05:16.427: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.431: DR: 192.168.1.4 (Id) BDR: 192.168.1.3 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.431: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:16.431: OSPF: Rcv DBD from 192.168.1.3 on FastEthernet0/0 seq 0x101B opt 0x52 flag 0x7 len 32 mtu 1500 state EXSTART[/FONT]
[FONT=&quot]*Mar 1 00:05:16.435: OSPF: First DBD and we are not SLAVE[/FONT]
[FONT=&quot]*Mar 1 00:05:16.435: OSPF: Rcv DBD from 192.168.1.1 on FastEthernet0/0 seq 0x1B2 opt 0x52 flag 0x7 len 32 mtu 1500 state INIT[/FONT]
[FONT=&quot]*Mar 1 00:05:16.435: OSPF: 2 Way Communication to 192.168.1.1 on FastEthernet0/0, state 2WAY[/FONT]
[FONT=&quot]*Mar 1 00:05:16.435: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.435: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.439: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.439: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.439: DR: 192.168.1.4 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.439: OSPF: Send DBD to 192.168.1.1 on FastEthernet0/0 seq 0x229C opt 0x52 flag 0x7 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:16.439: OSPF: First DBD and we are not SLAVE[/FONT]
[FONT=&quot]*Mar 1 00:05:16.443: OSPF: Rcv hello from 192.168.1.1 area 0 from FastEthernet0/0 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.443: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.443: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.443: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.447: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.447: DR: 192.168.1.4 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.447: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:16.447: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0x2640 opt 0x52 flag 0x7 len 32 mtu 1500 state INIT[/FONT]
[FONT=&quot]*Mar 1 00:05:16.447: OSPF: 2 Way Communication to 192.168.1.2 on FastEthernet0/0, state 2WAY[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: DR: 192.168.1.4 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.451: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0x1519 opt 0x52 flag 0x7 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:16.455: OSPF: First DBD and we are not SLAVE[/FONT]
[FONT=&quot]*Mar 1 00:05:16.619: OSPF: Rcv hello from 192.168.1.2 area 0 from FastEthernet0/0 192.168.1.2[/FONT]
[FONT=&quot]*Mar 1 00:05:16.619: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.619: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 00:05:16.619: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.623: OSPF: Elect DR 192.168.1.4[/FONT]
[FONT=&quot]*Mar 1 00:05:16.623: DR: 192.168.1.4 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 00:05:16.623: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 00:05:16.691: OSPF: Rcv DBD from 192.168.1.3 on FastEthernet0/0 seq 0x15 opt 0x52 flag 0x2 len 172 mtu 1500 state EXSTART[/FONT]
[FONT=&quot]*Mar 1 00:05:16.691: OSPF: NBR Negotiation Done. We are the MASTER[/FONT]
[FONT=&quot]*Mar 1 00:05:16.695: OSPF: Send DBD to 192.168.1.3 on FastEthernet0/0 seq 0x16 opt 0x52 flag 0x3 len 72[/FONT]
[FONT=&quot]*Mar 1 00:05:16.787: OSPF: Rcv DBD from 192.168.1.1 on FastEthernet0/0 seq 0x229C opt 0x52 flag 0x2 len 172 mtu 1500 state EXSTART[/FONT]
[FONT=&quot]*Mar 1 00:05:16.787: OSPF: NBR Negotiation Done. We are the MASTER[/FONT]
[FONT=&quot]*Mar 1 00:05:16.791: OSPF: Send DBD to 192.168.1.1 on FastEthernet0/0 seq 0x229D opt 0x52 flag 0x3 len 72[/FONT]
[FONT=&quot]*Mar 1 00:05:16.855: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0x1519 opt 0x52 flag 0x2 len 172 mtu 1500 state EXSTART[/FONT]
[FONT=&quot]*Mar 1 00:05:16.855: OSPF: NBR Negotiation Done. We are the MASTER[/FONT]
[FONT=&quot]*Mar 1 00:05:16.859: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0x151A opt 0x52 flag 0x3 len 72[/FONT]
[FONT=&quot]*Mar 1 00:05:16.915: OSPF: Rcv DBD from 192.168.1.3 on FastEthernet0/0 seq 0x16 opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE[/FONT]
[FONT=&quot]*Mar 1 00:05:16.919: OSPF: Send DBD to 192.168.1.3 on FastEthernet0/0 seq 0x17 opt 0x52 flag 0x1 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:16.919: OSPF: Send LS REQ to 192.168.1.3 length 84 LSA count 7[/FONT]
[FONT=&quot]*Mar 1 00:05:16.923: OSPF: Rcv LS UPD from 192.168.1.1 on FastEthernet0/0 length 76 LSA count 1[/FONT]
[FONT=&quot]*Mar 1 00:05:16.999: OSPF: Rcv LS UPD from 192.168.1.3 on FastEthernet0/0 length 76 LSA count 1[/FONT]
[FONT=&quot]*Mar 1 00:05:17.003: OSPF: Rcv LS UPD from 192.168.1.2 on FastEthernet0/0 length 76 LSA count 1[/FONT]
[FONT=&quot]*Mar 1 00:05:17.003: OSPF: Rcv DBD from 192.168.1.1 on FastEthernet0/0 seq 0x229D opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE[/FONT]
[FONT=&quot]*Mar 1 00:05:17.007: OSPF: Send DBD to 192.168.1.1 on FastEthernet0/0 seq 0x229E opt 0x52 flag 0x1 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:17.007: OSPF: Send LS REQ to 192.168.1.1 length 48 LSA count 4[/FONT]
[FONT=&quot]*Mar 1 00:05:17.191: OSPF: Rcv LS REQ from 192.168.1.3 on FastEthernet0/0 length 48 LSA count 2[/FONT]
[FONT=&quot]*Mar 1 00:05:17.191: OSPF: Send UPD to 192.168.1.3 on FastEthernet0/0 length 68 LSA count 2[/FONT]
[FONT=&quot]*Mar 1 00:05:17.195: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0x151A opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE[/FONT]
[FONT=&quot]*Mar 1 00:05:17.195: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0x151B opt 0x52 flag 0x1 len 32[/FONT]
[FONT=&quot]*Mar 1 00:05:17.199: OSPF: Send LS REQ to 192.168.1.2 length 48 LSA count 4[/FONT]

bon_chan

Here is a sh ip ospf int on R3:

[FONT=&quot]R3#sh ip ospf interface[/FONT]
[FONT=&quot]FastEthernet0/0 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 192.168.1.3/24, Area 0[/FONT]
[FONT=&quot] Process ID 333, Router ID 192.168.1.3, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State DR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.1.3, Interface address 192.168.1.3[/FONT]
[FONT=&quot] Backup Designated router (ID) 192.168.1.2, Interface address 192.168.1.2[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:04[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/1, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 1, maximum is 1[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 4 msec[/FONT]
[FONT=&quot] Neighbor Count is 2, Adjacent neighbor count is 2[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.1.1[/FONT]
[FONT=&quot] Adjacent with neighbor 192.168.1.2 (Backup Designated Router)[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]FastEthernet0/1 is up, line protocol is up[/FONT]
[FONT=&quot] Internet Address 172.13.0.1/29, Area 3[/FONT]
[FONT=&quot] Process ID 333, Router ID 192.168.1.3, Network Type BROADCAST, Cost: 10[/FONT]
[FONT=&quot] Transmit Delay is 1 sec, State DR, Priority 1[/FONT]
[FONT=&quot] Designated Router (ID) 192.168.1.3, Interface address 172.13.0.1[/FONT]
[FONT=&quot] No backup designated router on this network[/FONT]
[FONT=&quot] Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5[/FONT]
[FONT=&quot] oob-resync timeout 40[/FONT]
[FONT=&quot] Hello due in 00:00:04[/FONT]
[FONT=&quot] Supports Link-local Signaling (LLS)[/FONT]
[FONT=&quot] Index 1/2, flood queue length 0[/FONT]
[FONT=&quot] Next 0x0(0)/0x0(0)[/FONT]
[FONT=&quot] Last flood scan length is 0, maximum is 0[/FONT]
[FONT=&quot] Last flood scan time is 0 msec, maximum is 0 msec[/FONT]
[FONT=&quot] Neighbor Count is 0, Adjacent neighbor count is 0[/FONT]
[FONT=&quot] Suppress hello for 0 neighbor(s)[/FONT]
[FONT=&quot]R3#[/FONT]

And here is a debug ip ospf events on R3 after having R2 back to normal (and before adding R4 to the topology):
[FONT=&quot]*Mar 1 03:23:11.131: OSPF: Send immediate hello to nbr 192.168.1.2, src address 192.168.1.2, on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.131: OSPF: Send hello to 192.168.1.2 area 0 on FastEthernet0/0 from 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 03:23:11.135: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 03:23:11.343: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0x160A opt 0x52 flag 0x7 len 32 mtu 1500 state INIT[/FONT]
[FONT=&quot]*Mar 1 03:23:11.343: OSPF: 2 Way Communication to 192.168.1.2 on FastEthernet0/0, state 2WAY[/FONT]
[FONT=&quot]*Mar 1 03:23:11.347: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.347: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.351: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 03:23:11.351: OSPF: Elect DR 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 03:23:11.351: DR: 192.168.1.3 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 03:23:11.355: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0xC5F opt 0x52 flag 0x7 len 32[/FONT]
[FONT=&quot]*Mar 1 03:23:11.359: OSPF: First DBD and we are not SLAVE[/FONT]
[FONT=&quot]*Mar 1 03:23:11.383: OSPF: Rcv hello from 192.168.1.2 area 0 from FastEthernet0/0 192.168.1.2[/FONT]
[FONT=&quot]*Mar 1 03:23:11.387: OSPF: Neighbor change Event on interface FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.387: OSPF: DR/BDR election on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.387: OSPF: Elect BDR 192.168.1.1[/FONT]
[FONT=&quot]*Mar 1 03:23:11.391: OSPF: Elect DR 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 03:23:11.391: DR: 192.168.1.3 (Id) BDR: 192.168.1.1 (Id)[/FONT]
[FONT=&quot]*Mar 1 03:23:11.395: OSPF: End of hello processing[/FONT]
[FONT=&quot]*Mar 1 03:23:11.439: OSPF: Send hello to 224.0.0.5 area 0 on FastEthernet0/0 from 192.168.1.3[/FONT]
[FONT=&quot]*Mar 1 03:23:11.475: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0xC5F opt 0x52 flag 0x2 len 192 mtu 1500 state EXSTART[/FONT]
[FONT=&quot]*Mar 1 03:23:11.479: OSPF: NBR Negotiation Done. We are the MASTER[/FONT]
[FONT=&quot]*Mar 1 03:23:11.483: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0xC60 opt 0x52 flag 0x3 len 172[/FONT]
[FONT=&quot]*Mar 1 03:23:11.607: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0xC60 opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE[/FONT]
[FONT=&quot]*Mar 1 03:23:11.607: OSPF: Send DBD to 192.168.1.2 on FastEthernet0/0 seq 0xC61 opt 0x52 flag 0x1 len 32[/FONT]
[FONT=&quot]*Mar 1 03:23:11.607: OSPF: Send LS REQ to 192.168.1.2 length 24 LSA count 2[/FONT]
[FONT=&quot]*Mar 1 03:23:11.735: OSPF: Rcv DBD from 192.168.1.2 on FastEthernet0/0 seq 0xC61 opt 0x52 flag 0x0 len 32 mtu 1500 state EXCHANGE[/FONT]
[FONT=&quot]*Mar 1 03:23:11.739: OSPF: Exchange Done with 192.168.1.2 on FastEthernet0/0[/FONT]
[FONT=&quot]*Mar 1 03:23:11.819: OSPF: Rcv LS UPD from 192.168.1.2 on FastEthernet0/0 length 96 LSA count 2[/FONT]
[FONT=&quot]*Mar 1 03:23:11.827: OSPF: Synchronized with 192.168.1.2 on FastEthernet0/0, state FULL[/FONT]
[FONT=&quot]*Mar 1 03:23:11.827: %OSPF-5-ADJCHG: Process 333, Nbr 192.168.1.2 on FastEthernet0/0 from LOADING to FULL, Loading Done[/FONT]
[FONT=&quot]*Mar 1 03:23:12.451: OSPF: Send hello to 224.0.0.5 area 3 on FastEthernet0/1 from 172.13.0.1[/FONT]

Netwurk

Here's something to try in a GNS3 lab when working with DR/BDR

Bring up two routers and connect two serial interfaces together

Use the show ip ospf neighbor command

States will show as FULL/ - on both routers

Add an ip ospf network broadcast to the config of both serial interfaces. Then do a shut/no shut on both.

You'll now see FULL/DR and FULL/BDR for the OSPF states of your routers

This scenario is more useful with a real lab as you can use this tip to add more OSPF broadcast links to your lab.

I doubt there's a use for this in a production environment, so don't try this at work.