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Question about OSPF

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comptek

Technical User
Nov 8, 2002
102
US
Guys I am going to be sitting the ICND here pretty soon and was running through some exam sims and ran into a problem configuring ospf. I finally got it but my question is will any of the ways that the Sybex book by Todd Lammle explained on how to configure ospf work on the ICND? For example routerA E0: 192.168.33.1 /24, S0: 192.168.100.5/30. When asked to configure ospf on this router I would just do router ospf 1, network 192.168.33.1 0.0.0.0 area 0, and network 192.168.100.5 0.0.0.0 area 0 for the other, or I would have done 192.168.33.0 0.0.0.255 area 0,and 192.168.100.0 0.0.0.255 area 0. Both of these were in the Lammle book and I remember that the book said that the 0.0.0.255 or 0.0.0.0 wild card would be fine. I am enclosing a router console sim I did and you will see that when I ran the 0.0.0.255 wild card the route table would not populate but when I changed it to match the way ospf was configured on the others it worked fine. Is it just this sim or will the ICND sim be picky and want it configured the same way as the others to keep consistent? Maybe it is just my anxiety. Sorry if it is too long. Here is the config:

Alpha>en
Password:xxxx
Alpha#sh run
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Alpha
!
!
enable password how2pass
!
ip subnet-zero
!
!
interface Ethernet0
ip address 192.168.33.1 255.255.255.0
no ip directed-broadcast
!
interface Serail0
ip address 192.168.100.5 255.255.255.252
no ip directed-broadcast
clock rate 64000
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
router ospf 1
network 192.168.100.4 0.0.0.255 area 1 (this was the problem)
network 192.168.33.0 0.0.0.255 area 0
!
!
no ip classless
!
!
!
line con 0
line aux 0
line vty 0 4
!
end
Alpha#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
Alpha#config t
Enter configuration commands, one per line. End with CNTL/Z.

Alpha(config)#no router ospf 1 (removed ospf config)
Alpha(config)#router ospf 1
% Invalid input detected.

Alpha(config)#router ospf 1
Alpha(config-router)#network 192.168.33.0 0.0.0.255 area 0 (can do it like this or full ip followed with all 0's area 0 in Sybex)
Alpha(config-router)#network 192.168.100.0 0.0.0.255 area 0 (same here)
Alpha(config-router)#exit
Alpha(config)#exit
Alpha#sh run
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Alpha
!
!
enable password how2pass
!
ip subnet-zero
!
!
interface Ethernet0
ip address 192.168.33.1 255.255.255.0
no ip directed-broadcast
!
interface Serail0
ip address 192.168.100.5 255.255.255.252
no ip directed-broadcast
clock rate 64000
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
router ospf 1
network 192.168.33.0 0.0.0.255 area 0 (now in correct ospf area)
network 192.168.100.0 0.0.0.255 area 0
!
!
no ip classless
!
!
!
line con 0
line aux 0
line vty 0 4
!
end
Alpha#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
            D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
            N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
            E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
            i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
            U - per-user static route, o - ODR

Gateway of last resort is not set

C 192.168.100.4/30 is directly connected. Serial0
C 192.168.33.0/24 is directly connected. Ethernet0
(No ospf in table)
Alpha#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
            D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
            N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
            E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
            i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
            U - per-user static route, o - ODR

Gateway of last resort is not set

C 192.168.100.4/30 is directly connected. Serial0
C 192.168.33.0/24 is directly connected. Ethernet0

Alpha#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface

I did a show run again to verify my config
Alpha#sh run
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Alpha
!
!
enable password how2pass
!
ip subnet-zero
!
!
interface Ethernet0
ip address 192.168.33.1 255.255.255.0
no ip directed-broadcast
!
interface Serail0
ip address 192.168.100.5 255.255.255.252
no ip directed-broadcast
clock rate 64000
!
interface Serial1
no ip address
no ip directed-broadcast
shutdown
!
router ospf 1
network 192.168.33.0 0.0.0.255 area 0
network 192.168.100.0 0.0.0.255 area 0
!
!
no ip classless
!
!
!
line con 0
line aux 0
line vty 0 4
!
end

At first I thought that it may be just the router taking time to populate tables so I checked the route table again.
Alpha#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
            D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
            N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
            E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
            i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
            U - per-user static route, o - ODR

Gateway of last resort is not set

C 192.168.100.4/30 is directly connected. Serial0
C 192.168.33.0/24 is directly connected. Ethernet0

Nothing again so I checked interfaces to make sure they were up ok
Alpha#sh int e0
Ehternet0 is up, line protocol is up
Hardware is HD64570
Description:
Internet address is 192.168.33.1
    MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 252/255, load 1/255
    Encapsulation ARPA, loopback not set, keepalive set (10 sec)
    ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Alpha#sh int s0
Serial0 is up, line protocol is up
Hardware is HD64570
Description:
Internet address is 192.168.100.5
    MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
    Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input never, output never, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/0/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 packets output, 0 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=down DSR=down DTR=down RTS=down CTS=down

Went to the directly connected router and looked at there config and
Alpha#config t
Enter configuration commands, one per line. End with CNTL/Z.

Alpha(config)#no router ospf 1
Alpha(config)#router ospf 1
Alpha(config-router)#network 192.168.33.0 0.0.0.255 area 0
Alpha(config-router)#network 192.168.100.4 0.0.0.3 area 0 (why this way works but not config above)
Alpha(config-router)#exit
Alpha(config)#exit

The desired result.
Alpha#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
            D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
            N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
            E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
            i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
            U - per-user static route, o - ODR

Gateway of last resort is not set

C 192.168.100.4/30 is directly connected. Serial0
C 192.168.33.0/24 is directly connected. Ethernet0
O 192.168.100.8/30 [110/64] via 192.168.100.6, 00:00:35, Serial0
O 192.168.34.0/24 [110/64] via 192.168.100.6, 00:00:35, Serial0
O 192.168.35.0/24 [110/128] via 192.168.100.6, 00:00:35, Serial0

Comptek
A+, Network+
 
Without plugging your config into a couple of routers of my own, I can't come up with any reason why all those configs work. It shouldn't matter about the mask in how you are doing it, but hopefully CiscoGuy will chime in and have something really good for you.

Only thing I can think of is if it was taking OSPF a little bit to converge. Maybe run a "debug ip ospf events" It should give you a litte more insight as to what is going on.

 
Thanks lerdalt,

Just like you I thought the mask was fine using either 0.0.0.0 or 0.0.0.255. I know that 0.0.0.0 is more specific and if I used 0.0.0.255 it would cover anything in that range. I think it is this exam sim that i am using. It seems like they wrote the result with one possible answer eventhough there are other ways of answering it. But if anyone else can find an issue with the config I would appreciate it. Just wanted to be as prepared as I can for the icnd. For a second I thought when I got the sim wrong that I did not know how to config ospf!!!! Crazy how your mind starts to think bad thoughts the closer you get to exam day.

Have a good one.

Comptek
A+, Network+
 
What other routers/interfaces/IP addresses are in Area 0?

Burt
 
Burt,

Here are the other 2 routers. I dont have time to go through the sim to get the whole config but here are the router ip's
RouterB
E0: 192.168.34.1 /24
S0: 192.168.100.10 /30 Connects to RouterC S1
S1: 192.168.100.6 /30 Connects to RouterA S0
Ospf set to area 0
RouterC
E0: 192.168.35.1 /24
S1: 192.168.100.9 /30 Connects to RouterB S0
Ospf set to area 0.

Not sure if this is what you were looking for but if you want the config for the others i'll try and get it this afternoon. Just so you know that after I set the OSPF config the way the others were set ex( 0.0.0.3) was the wildcard that fixed it.

Charlie

Comptek
A+, Network+
 
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