OBJECTIVE:
1. To have atleast clear understanding of the OSPF LSA types.
2. Setup a two area OSPF network and understand the OSPF Database contents.
3. Show how OSPF LSA Type 1, Type 2 and Type 3 were created.
4. Select MELBOURNE as the DR for the OSPF Broadcast and will not allow both MANILA & SINGAPORE for the election.
POINTS TO REMEMBER ON OSPF LSA TYPES:
MANILA Router Configurations:
R1#config t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#hostname MANILA
MANILA(config)#int lo1
MANILA(config-if)#ip add 10.10.10.1 255.255.255.0
MANILA(config-if)#exit
MANILA(config)#int s2/0
MANILA(config-if)#ip add 192.168.12.1 255.255.255.0
MANILA(config-if)#no shut
MANILA(config-if)#exit
MANILA(config)#router ospf 1
MANILA(config-router)#network 192.168.12.0 0.0.0.255 area 0
MANILA(config-router)#network 10.10.10.0 0.0.0.255 area 0
MANILA(config-router)#^Z
MELBOURNE Router Configurations:
R2#config t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#hostname MELBOURNE
MELBOURNE(config)#int lo2
MELBOURNE(config-if)#ip add 20.20.20.1 255.255.255.0
MELBOURNE(config-if)#exit
MELBOURNE(config)#int s2/0
MELBOURNE(config-if)#ip address 192.168.12.2 255.255.255.0
MELBOURNE(config-if)#no shut
MELBOURNE(config-if)#exit
MELBOURNE(config)#int s2/1
MELBOURNE(config-if)#ip add 192.168.23.2 255.255.255.0
MELBOURNE(config-if)#no shut
MELBOURNE(config-if)#exit
MELBOURNE(config)#router ospf 1
MELBOURNE(config-router)#network 192.168.12.0 0.0.0.255 area 0
MELBOURNE(config-router)#network 20.20.20.0 0.0.0.255 area 0 <<< In my configs, I am advertising the Loopback in AREA 0.
MELBOURNE(config-router)#network 192.168.23.0 0.0.0.255 area 1
SINGAPORE Router Configurations:
R3#config t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#hostname SINGAPORE
SINGAPORE(config)#int lo3
SINGAPORE(config-if)#ip add 30.30.30.1 255.255.255.0
SINGAPORE(config-if)#int s2/1
SINGAPORE(config-if)#ip add 192.168.23.3 255.255.255.0
SINGAPORE(config-if)#no shut
SINGAPORE(config-if)#exit
SINGAPORE(config)#router ospf 1
SINGAPORE(config-router)#network 192.168.23.0 0.0.0.255 area 1
SINGAPORE(config-router)#network 30.30.30.0 0.0.0.255 area 1
VERIFICATION:
A. Now, lets check whether the adjacencies were established,
MANILA#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
20.20.20.1 0 FULL/ – 00:00:33 192.168.12.2 Serial2/0
MANILA#
MELBOURNE#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 0 FULL/ – 00:00:36 192.168.12.1 Serial2/0
30.30.30.1 0 FULL/ – 00:00:32 192.168.23.3 Serial2/1
MELBOURNE#
SINGAPORE#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
20.20.20.1 0 FULL/ – 00:00:39 192.168.23.2 Serial2/1
SINGAPORE#
B. Let’s check the OSPF Database of the ABR Router (MELBOURNE).
MELBOURNE#show ip ospf database
OSPF Router with ID (20.20.20.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.10.10.1 10.10.10.1 28 0x80000007 0x008B7B 3
20.20.20.1 20.20.20.1 21 0x80000006 0x00E6E2 3
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
30.30.30.1 20.20.20.1 7 0x80000001 0x00E77B
192.168.23.0 20.20.20.1 17 0x80000001 0x0074CA
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
20.20.20.1 20.20.20.1 21 0x80000006 0x003095 2
30.30.30.1 30.30.30.1 15 0x80000003 0x0075C8 3
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.10.10.1 20.20.20.1 17 0x80000001 0x00BAE4
20.20.20.1 20.20.20.1 17 0x80000001 0x00CEF2
192.168.12.0 20.20.20.1 17 0x80000001 0x00ED5C
MELBOURNE#
>> As observed, we can see the Router LSA (Type 1) and Type 3 ( Summary LSA).
NOTE: If I will be using Fasthernet link I should be able to see the third OSPF LSA types which is the NETWORK LSA or LSA Type 3.
I have changed the OSPF interface from Serial Links to a Fastethernet link to show the concepts. So here is my modified configurations on the Interface. Take note, I did not change my OSPF Configurations.. THIS IS THE BEAUTY BROUGHT BY GNS3..Kudos to the developer.
MELBOURNE#sh run int fa1/1
Building configuration…
Current configuration : 97 bytes
!
interface FastEthernet1/1
ip address 192.168.12.2 255.255.255.0
speed auto
duplex auto
end
MELBOURNE#sh run int fa0/0
Building configuration…
Current configuration : 85 bytes
!
interface FastEthernet0/0
ip address 192.168.23.2 255.255.255.0
duplex full
end
MANILA#sh run int fa1/1
Building configuration…
Current configuration : 97 bytes
!
interface FastEthernet1/1
ip address 192.168.12.1 255.255.255.0
speed auto
duplex auto
end
SINGAPORE#sh run int fa0/0
Building configuration…
Current configuration : 85 bytes
!
interface FastEthernet0/0
ip address 192.168.23.3 255.255.255.0
duplex full
end
Now, let check the OSPF DATABASE again of the MELBOURNE Router,
MELBOURNE#show ip ospf database
OSPF Router with ID (20.20.20.1) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.10.10.1 10.10.10.1 435 0x8000000A 0x00F8D4 2
20.20.20.1 20.20.20.1 321 0x8000000B 0x00AAC5 2
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
192.168.12.2 20.20.20.1 434 0x80000001 0x00D058
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
30.30.30.1 20.20.20.1 273 0x80000001 0x006F33
192.168.23.0 20.20.20.1 311 0x80000001 0x00FB82
Router Link States (Area 1)
Link ID ADV Router Age Seq# Checksum Link count
20.20.20.1 20.20.20.1 278 0x80000009 0x000B9E 1
30.30.30.1 30.30.30.1 279 0x80000006 0x00748F 2
Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
192.168.23.3 30.30.30.1 279 0x80000001 0x00B60C
Summary Net Link States (Area 1)
Link ID ADV Router Age Seq# Checksum
10.10.10.1 20.20.20.1 278 0x80000002 0x00409D
20.20.20.1 20.20.20.1 321 0x80000001 0x00CEF2
192.168.12.0 20.20.20.1 278 0x80000002 0x007315
MELBOURNE#
>>> So what can we see from the above results, now I can see that OSPF LSA TYPE 2 were included.
>>> Similarly, check what happens to the OSPF Neighbor?
MELBOURNE#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 1 FULL/BDR 00:00:35 192.168.12.1 FastEthernet1/1
30.30.30.1 1 FULL/DR 00:00:32 192.168.23.3 FastEthernet0/0
MELBOURNE#
>> As seen, SINGAPORE router were elected as the DR as by default, it has the highest active Loopback IP address.
>> But as a good practice, I want to change the DR to MELBOURNE Router. But let’s check the COST of both links towards MANILA and SINGAPORE router. As we have seen below, the COST were set to 1 as the default BW for the Ethernet links is 100 Mbps. Remember how the previous formula on cost which I have shared.
MELBOURNE#sh ip ospf int fastEthernet 0/0
FastEthernet0/0 is up, line protocol is up
Internet Address 192.168.23.2/24, Area 1, Attached via Network Statement
Process ID 1, Router ID 20.20.20.1, Network Type BROADCAST, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 30.30.30.1, Interface address 192.168.23.3
Backup Designated router (ID) 20.20.20.1, Interface address 192.168.23.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
MELBOURNE#sh ip ospf int fastEthernet 1/1
FastEthernet1/1 is up, line protocol is up
Internet Address 192.168.12.2/24, Area 0, Attached via Network Statement
Process ID 1, Router ID 20.20.20.1, Network Type BROADCAST, Cost: 1
Topology-MTID Cost Disabled Shutdown Topology Name
0 1 no no Base
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 20.20.20.1, Interface address 192.168.12.2
Backup Designated router (ID) 10.10.10.1, Interface address 192.168.12.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Now, I want to change so that MELBOURNE will be the DR and will not allow both MANILA & SINGAPORE router to participates in the election process.
Alright, here is my configurations on MANILA & SINGAPORE router.
MANILA#config t
Enter configuration commands, one per line. End with CNTL/Z.
MANILA(config)#int fa1/1
MANILA(config-if)#ip ospf priority 0
SINGAPORE#config t
Enter configuration commands, one per line. End with CNTL/Z.
SINGAPORE(config)#int fa0/0
SINGAPORE(config-if)#ip ospf priority 0
MELBOURNE#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 0 FULL/DROTHER 00:00:32 192.168.12.1 FastEthernet1/1
30.30.30.1 0 FULL/DROTHER 00:00:37 192.168.23.3 FastEthernet0/0
MELBOURNE#
MANILA#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
20.20.20.1 1 FULL/DR 00:00:39 192.168.12.2 FastEthernet1/1
MANILA#
SINGAPORE#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
20.20.20.1 255 FULL/DR 00:00:35 192.168.23.2 FastEthernet0/0
SINGAPORE#
C. Another Verifications we can check is the routing table and the connectivity between the three networks.
SINGAPORE#show ip route ospf
Codes: L – local, C – connected, S – static, 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
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
+ – replicated route, % – next hop override
Gateway of last resort is not set
10.0.0.0/32 is subnetted, 1 subnets
O IA 10.10.10.1 [110/3] via 192.168.23.2, 00:04:03, FastEthernet0/0
20.0.0.0/32 is subnetted, 1 subnets
O IA 20.20.20.1 [110/2] via 192.168.23.2, 00:04:03, FastEthernet0/0
O IA 192.168.12.0/24 [110/2] via 192.168.23.2, 00:04:03, FastEthernet0/0
SINGAPORE#
MANILA#sho ip route ospf
Codes: L – local, C – connected, S – static, 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
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
+ – replicated route, % – next hop override
Gateway of last resort is not set
20.0.0.0/32 is subnetted, 1 subnets
O 20.20.20.1 [110/2] via 192.168.12.2, 00:05:13, FastEthernet1/1
30.0.0.0/32 is subnetted, 1 subnets
O IA 30.30.30.1 [110/3] via 192.168.12.2, 00:05:02, FastEthernet1/1
O IA 192.168.23.0/24 [110/2] via 192.168.12.2, 00:05:13, FastEthernet1/1
MANILA#
MELBOURNE#show ip route ospf
Codes: L – local, C – connected, S – static, 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
i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
ia – IS-IS inter area, * – candidate default, U – per-user static route
o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
+ – replicated route, % – next hop override
Gateway of last resort is not set
10.0.0.0/32 is subnetted, 1 subnets
O 10.10.10.1 [110/2] via 192.168.12.1, 00:05:36, FastEthernet1/1
30.0.0.0/32 is subnetted, 1 subnets
O 30.30.30.1 [110/2] via 192.168.23.3, 00:05:26, FastEthernet0/0
MELBOURNE#
>>> As observed, those routing entries with O IA were considered as TYPE 3 LSA that were summarized by MELBOURNE router.
D. Finally, I want to test the connectivity.
MANILA#ping 30.30.30.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 30.30.30.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 56/63/88 ms
MANILA#traceroute 30.30.30.1
Type escape sequence to abort.
Tracing the route to 30.30.30.1
VRF info: (vrf in name/id, vrf out name/id)
1 192.168.12.2 48 msec 56 msec 56 msec
2 192.168.23.3 56 msec 56 msec 56 msec
MANILA#
NETWORK LESSON 
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