Learning Objectives:
Upon completion of this lab, you will be able to:
Cable a network according to the Topology Diagram
Erase the startup configuration and reload a router to the default state
Perform basic configuration tasks on a router
Configure and activate interfaces
Configure OSPF routing on all routers
Configure OSPF router IDs
Verify OSPF routing using show commands
Configure a static default route
Propagate default route to OSPF neighbors
Configure OSPF Hello and Dead Timers
Configure OSPF on a Multi-access network
Configure OSPF priority
Understand the OSPF election process
Document the OSPF configuration
Scenarios:
In this lab activity, there are two separate scenarios. In the first scenario, you will learn how to
configure the routing protocol OSPF using the network shown in the Topology Diagram in
Scenario A. The segments of the network have been subnetted using VLSM. OSPF is a classless
routing protocol that can be used to provide subnet mask information in the routing updates. This
will allow VLSM subnet information to be propagated throughout the network.
In the second scenario, you will learn to configure OSPF on a multi-access network. You will also
learn to use the OSPF election process to determine the designated router (DR), backup
designated router (BDR), and DRother states.
Addressing Table:
Prepare the Network:
Cable a network that is similar to the one in the Topology Diagram.
You can use any current router in your lab as long as it has the required interfaces shown in the
topology. If you use 1700, 2500, or 2600 routers, the router outputs and interface descriptions will appear different. Clear any existing configurations on the routers.
Perform Basic Router Configurations:
Perform basic configuration of the R1, R2, and R3 routers according to the following guidelines:
1. Configure the router hostname.
2. Disable DNS lookup.
3. Configure a privileged EXEC mode password.
4. Configure a message-of-the-day banner.
5. Configure a password for console connections.
6. Configure a password for VTY connections.
Configure and Activate Serial and Ethernet Addresses. Configure interfaces on R1, R2, and R3. Configure the interfaces on the R1, R2, and R3 routers with the IP addresses from the table under the Topology Diagram. Verify IP addressing and interfaces.Use the show ip interface brief command to verify that the IP addressing is correct and that the interfaces are active. When you have finished, be sure to save the running configuration to the NVRAM of the router. Configure Ethernet interfaces of PC1, PC2, and PC3. Configure the Ethernet interfaces of PC1, PC2, and PC3 with the IP addresses and default gateways from the table under the Topology Diagram. Test the PC configuration by pinging the default gateway from the PC.
Configure OSPF on the R1 Router:
Use the router ospf command in global configuration mode to enable OSPF on the R1 router. Enter a process ID of 1 for the process-ID parameter.
R1(config)#router ospf 1
R1(config-router)#
Configure the network statement for the LAN network. Once you are in the Router OSPF configuration sub-mode, configure the LAN network 172.16.1.16/28 to be included in the OSPF updates that are sent out of R1. The OSPF network command uses a combination of network-address and wildcard-mask similar to that which can be used by EIGRP. Unlike EIGRP, the wildcard mask in OSPF is required.Use an area ID of 0 for the OSPF area-id parameter. 0 will be used for the OSPF area ID in all of the network statements in this topology.
R1(config-router)#network 172.16.1.16 0.0.0.15 area 0
R1(config-router)#
Configure the router to advertise the 192.168.10.0/30 network attached to the
Serial0/0/0 interface.
R1(config-router)# network 192.168.10.0 0.0.0.3 area 0
R1(config-router)#
Configure the router to advertise the 192.168.10.4/30 network attached to the
Serial0/0/1 interface.
R1(config-router)# network 192.168.10.4 0.0.0.3 area 0
R1(config-router)#
When you are finished with the OSPF configuration for R1, return to privileged
EXEC mode.
R1(config-router)#end
%SYS-5-CONFIG_I: Configured from console by console
R1#
Task 5: Configure OSPF on the R2 and R3 Routers
Enable OSPF routing on the R2 router using the router ospf command.
Use a process ID of 1.
R2(config)#router ospf 1
R2(config-router)#
Configure the router to advertise the LAN network 10.10.10.0/24 in the OSPF
updates.
R2(config-router)#network 10.10.10.0 0.0.0.255 area 0
R2(config-router)#
Step 3: Configure the router to advertise the 192.168.10.0/30 network attached to the
Serial0/0/0 interface.
R2(config-router)#network 192.168.10.0 0.0.0.3 area 0
R2(config-router)#
00:07:27: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.5 on Serial0/0/0
from EXCHANGE to FULL, Exchange Done
Notice that when the network for the serial link from R1 to R2 is added to the OSPF configuration, the router sends a notification message to the console stating that a neighbor relationship with another OSPF router has been established.
Configure the router to advertise the 192.168.10.8/30 network attached to the
Serial0/0/1 interface:
When you are finished, return to privileged EXEC mode.
R2(config-router)#network 192.168.10.8 0.0.0.3 area 0
R2(config-router)#end
%SYS-5-CONFIG_I: Configured from console by console
R2#
Configure OSPF on the R3 router using the router ospf and network
commands.
Use a process ID of 1. Configure the router to advertise the three directly connected networks.
When you are finished, return to privileged EXEC mode.
R3(config)#router ospf 1
R3(config-router)#network 172.16.1.32 0.0.0.7 area 0
R3(config-router)#network 192.168.10.4 0.0.0.3 area 0
R3(config-router)#
00:17:46: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.5 on Serial0/0/0
from LOADING to FULL, Loading Done
R3(config-router)#network 192.168.10.8 0.0.0.3 area 0
R3(config-router)#
00:18:01: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.9 on Serial0/0/1
from EXCHANGE to FULL, Exchange Done
R3(config-router)#end
%SYS-5-CONFIG_I: Configured from console by console
R3#
Notice that when the networks for the serial links from R3 to R1 and R3 to R2 are added to the
OSPF configuration, the router sends a notification message to the console stating that a
neighbor relationship with another OSPF router has been established.
Configure OSPF Router IDs
The OSPF router ID is used to uniquely identify the router in the OSPF routing domain. A router
ID is an IP address. Cisco routers derive the Router ID in one of three ways and with the following
precedence:
1. IP address configured with the OSPF router-id command.
2. Highest IP address of any of the router’s loopback addresses.
3. Highest active IP address on any of the router’s physical interfaces.
Current router IDs in the topology.
Since no router IDs or loopback interfaces have been configured on the three routers, the router
ID for each router is determined by the highest IP address of any active interface.
What is the router ID for R1? ____________________
What is the router ID for R2? ____________________
What is the router ID for R3? ____________________The router ID can also be seen in the output of the show ip protocols, show ip ospf, and
show ip ospf interfaces commands.
R3#show ip protocols
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 192.168.10.10
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
<output omitted>
R3#show ip ospf
Routing Process "ospf 1" with ID 192.168.10.10
Supports only single TOS(TOS0) routes
Supports opaque LSA
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
<output omitted>
R3#show ip ospf interface
FastEthernet0/0 is up, line protocol is up
Internet address is 172.16.1.33/29, Area 0
Process ID 1, Router ID 192.168.10.10, Network Type BROADCAST, Cost:
1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 192.168.10.10, Interface address 172.16.1.33
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:00
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
<output omitted>
R3#
Use loopback addresses to change the router IDs of the routers in the topology.
R1(config)#interface loopback 0
R1(config-if)#ip address 10.1.1.1 255.255.255.255
R2(config)#interface loopback 0
R2(config-if)#ip address 10.2.2.2 255.255.255.255
R3(config)#interface loopback 0
R3(config-if)#ip address 10.3.3.3 255.255.255.255
Reload the routers to force the new Router IDs to be used:
When a new Router ID is configured, it will not be used until the OSPF process is restarted. Make
sure that the current configuration is saved to NRAM, and then use the reload command to
restart each of the routers..
When the router is reloaded, what is the router ID for R1? ____________________
When the router is reloaded, what is the router ID for R2? ____________________
When the router is reloaded, what is the router ID for R3? ____________________
Use the show ip ospf neighbors command to verify that the router IDs have
changed.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
10.3.3.3 0 FULL/ - 00:00:30 192.168.10.6
Serial0/0/1
10.2.2.2 0 FULL/ - 00:00:33 192.168.10.2
Serial0/0/0
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
10.3.3.3 0 FULL/ - 00:00:36 192.168.10.10
Serial0/0/1
10.1.1.1 0 FULL/ - 00:00:37 192.168.10.1
Serial0/0/0
R3#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
10.2.2.2 0 FULL/ - 00:00:34 192.168.10.9
Serial0/0/1
10.1.1.1 0 FULL/ - 00:00:38 192.168.10.5
Serial0/0/0
Use the router-id command to change the router ID on the R1 router.
Note: Some IOS versions do not support the router-id command. If this command is not
available, continue to Task 7.
R1(config)#router ospf 1
R1(config-router)#router-id 10.4.4.4
Reload or use “clear ip ospf process” command, for this to take effect
If this command is used on an OSPF router process which is already active (has neighbors), the
new router-ID is used at the next reload or at a manual OSPF process restart. To manually restart
the OSPF process, use the clear ip ospf process command.
R1#(config-router)#end
R1# clear ip ospf process
Reset ALL OSPF processes? [no]:yes
R1#
Use the show ip ospf neighbor command on router R2 to verify that the router
ID of R1 has been changed.
R2#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
10.3.3.3 0 FULL/ - 00:00:36 192.168.10.10
Serial0/0/1
10.4.4.4 0 FULL/ - 00:00:37 192.168.10.1
Serial0/0/0
Remove the configured router ID with the no form of the router-id command.
R1(config)#router ospf 1
R1(config-router)#no router-id 10.4.4.4
Reload or use “clear ip ospf process” command, for this to take effect
Step 8: Restart the OSPF process using the clear ip ospf process command.
Restarting the OSPF process forces the router to use the IP address configured on the Loopback
0 interface as the Router ID.
R1(config-router)#end
R1# clear ip ospf process
Reset ALL OSPF processes? [no]:yes
R1#
Verify OSPF Operation
On the R1 router, Use the show ip ospf neighbor command to view the
information about the OSPF neighbor routers R2 and R3. You should be able to see the
neighbor ID and IP address of each adjacent router, and the interface that R1 uses to reach that
OSPF neighbor.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address
Interface
10.2.2.2 0 FULL/- 00:00:32 192.168.10.2
Serial0/0/0
10.3.3.3 0 FULL/- 00:00:32 192.168.10.6
Serial0/0/1
R1#
On the R1 router, use the show ip protocols command to view information
about the routing protocol operation.
Notice that the information that was configured in the previous Tasks, such as protocol, process. ID, neighbor ID, and networks, is shown in the output. The IP addresses of the adjacent neighbors are also shown.
R1#show ip protocols
Routing Protocol is "ospf 1"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 10.1.1.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.16 0.0.0.15 area 0
192.168.10.0 0.0.0.3 area 0
192.168.10.4 0.0.0.3 area 0
Routing Information Sources:
Gateway Distance Last Update
10.2.2.2 110 00:11:43
10.3.3.3 110 00:11:43
Distance: (default is 110)
R1#
Notice that the output specifies the process ID used by OSPF. Remember, the process ID must
be the same on all routers for OSPF to establish neighbor adjacencies and share routing information.
Examine OSPF Routes in the Routing Tables:
View the routing table on the R1 router. OSPF routes are denoted in the routing table with an “O”.
R1#show 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, ia - IS-IS
inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.1/32 is directly connected, Loopback0
O 10.10.10.0/24 [110/65] via 192.168.10.2, 00:01:02, Serial0/0/0
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.1.16/28 is directly connected, FastEthernet0/0
O 172.16.1.32/29 [110/65] via 192.168.10.6, 00:01:12, Serial0/0/1
192.168.10.0/30 is subnetted, 3 subnets
C 192.168.10.0 is directly connected, Serial0/0/0
C 192.168.10.4 is directly connected, Serial0/0/1
O 192.168.10.8 [110/128] via 192.168.10.6, 00:01:12, Serial0/0/1
[110/128] via 192.168.10.2, 00:01:02, Serial0/0/0
R1#
Notice that unlike RIPv2 and EIGRP, OSPF does not automatically summarize at major network
boundaries.
Configure OSPF Cost:
Use the show ip route command on the R1 router to view the OSPF cost to
reach the 10.10.10.0/24 network.
R1#show ip route
<output omitted>
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.1/32 is directly connected, Loopback0
O 10.10.10.0/24 [110/65] via 192.168.10.2, 00:16:56, Serial0/0/0
172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 172.16.1.16/28 is directly connected, FastEthernet0/0
O 172.16.1.32/29 [110/65] via 192.168.10.6, 00:17:06, Serial0/0/1
192.168.10.0/30 is subnetted, 3 subnets
C 192.168.10.0 is directly connected, Serial0/0/0
C 192.168.10.4 is directly connected, Serial0/0/1
O 192.168.10.8 [110/128] via 192.168.10.6, 00:17:06, Serial0/0/1
[110/128] via 192.168.10.2, 00:16:56, Serial0/0/0
R1#
Use the show interfaces serial0/0/0 command on the R1 router to view the
bandwidth of the Serial 0/0/0 interface.
R1#show interfaces serial0/0/0
Serial0/0/0 is up, line protocol is up (connected)
Hardware is HD64570
Internet address is 192.168.10.1/30
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
<output omitted>
On most serial links, the bandwidth metric will default to 1544 Kbits. If this is not the actual
bandwidth of the serial link, the bandwidth will need to be changed so that the OSPF cost can be calculated correctly. Use the bandwidth command to change the bandwidth of the serial interfaces of the R1 and R2 routers to the actual bandwidth, 64 kbps.
R1 router:
R1(config)#interface serial0/0/0
R1(config-if)#bandwidth 64
R1(config-if)#interface serial0/0/1
R1(config-if)#bandwidth 64
R2 router:
R2(config)#interface serial0/0/0
R2(config-if)#bandwidth 64
R2(config)#interface serial0/0/1
R2(config-if)#bandwidth 64
Use the show ip ospf interface command on the R1 router to verify the cost
of the serial links.
The cost of each of the Serial links is now 1562, the result of the calculation: 108/64,000 bps.
R1#show ip ospf interface
<output omitted>
Serial0/0/0 is up, line protocol is up
Internet address is 192.168.10.1/30, Area 0
Process ID 1, Router ID 10.1.1.1, Network Type POINT-TO-POINT, Cost:
1562
Transmit Delay is 1 sec, State POINT-TO-POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:05
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1 , Adjacent neighbor count is 1
Adjacent with neighbor 10.2.2.2
Suppress hello for 0 neighbor(s)
Serial0/0/1 is up, line protocol is up
Internet address is 192.168.10.5/30, Area 0
Process ID 1, Router ID 10.1.1.1, Network Type POINT-TO-POINT, Cost:
1562
Transmit Delay is 1 sec, State POINT-TO-POINT,
<output omitted>
Use the ip ospf cost command to configure the OSPF cost on the R3 router. An alternative method to using the bandwidth command is to use the ip ospf cost command, which allows you to directly configure the cost. Use the ip ospf cost command to the bandwidth of the serial interfaces of the R3 router to 1562.
R3(config)#interface serial0/0/0
R3(config-if)#ip ospf cost 1562
R3(config-if)#interface serial0/0/1
R3(config-if)#ip ospf cost 1562
Use the show ip ospf interface command on the R3 router to verify that the cost of the link the cost of each of the Serial links is now 1562.
R3#show ip ospf interface
<output omitted>
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