Lab 035 How to Configure and Verify OSPFv2 Router ID

CCNA 200-301 Chapter 3 IP Connectivity Lab 035 Configure and Verify OSPFv2 Router ID

Watch Full Demo on YouTube:

Lab Objective:

In this lab, you will learn how to configure and verify the OSPFv2 Router ID, a key element in the Open Shortest Path First (OSPF) protocol, which uniquely identifies routers in the OSPF domain. The Router ID is a 32-bit identifier typically written in the form of an IPv4 address. While it resembles an IP address, it does not have to be one configured on the router’s interfaces. Correctly configuring and verifying the Router ID is crucial for OSPF’s stable operation and ensuring routing information is accurately exchanged between routers.

This lab will help students deepen their knowledge of OSPFv2 configuration, specifically focusing on one of the foundational aspects of OSPF: the Router ID. Understanding how to configure and verify the Router ID is essential for anyone aiming to pass the CCNA certification exam.

Lab Topology:

CCNA 200-301 Lab Chapter 3 IP Connectivity Lab 035 Configure & Verify OSPFv2 Router ID – Topology

Equipment Required:

5x Cisco Router (e.g., Cisco ISR4331/K9)
6 x Cisco Switches (e.g., WS-C2960-24TT-L)
5 x Laptops with Ethernet Interface Card
Console Cable
Ethernet Cable for connections between devices
Computer with Terminal emulation software e.g. PuTTY

IPv4 Address Table:

A. IPv4 Address Table:

Device Name	Interface ID	IP Address	Subnet-Mask
R1	Loopback0	1.1.1.1	255.255.255.255
R1	Se0/3/0	10.0.0.1	255.255.255.252
R1	Gig0/1	192.168.10.254	255.255.255.0
R1	Gig0/2	192.168.20.254	255.255.255.0

R2	Loopback0	2.2.2.2	255.255.255.255
R2	Se0/3/0	10.0.0.2	255.255.255.252
R2	Gig0/0	10.10.10.2	255.255.255.248

R3	Loopback0	3.3.3.3	255.255.255.255
R3	Gig0/0	10.10.10.3	255.255.255.248
R3	Gig0/1	192.168.30.254	255.255.255.0

R4	Loopback0	4.4.4.4	255.255.255.255
R4	Gig0/0	10.10.10.4	255.255.255.248
R4	Gig0/1	192.168.40.254	255.255.255.0

R5	Loopback0	5.5.5.5	255.255.255.255
R5	Gig0/0	10.10.10.5	255.255.255.248
R5	Gig0/1	192.168.50.254	255.255.255.0

B. Hosts IP Address Table:

Device Name	Interface ID	IPv4 Address/Subnet-Mask	Default Gateway
PC1	Fa0	192.168.10.1/24	192.168.10.254
PC2	Fa0	192.168.20.1/24	192.168.20.254
PC3	Fa0	192.168.30.1/24	192.168.30.254
PC4	Fa0	192.168.40.1/24	192.168.40.254
PC5	Fa0	192.168.50.1/24	192.168.50.254

List of Command Summary:

Command	Command Description
enable	enters privileged EXEC mode.
configure terminal	enters global configuration mode from privileged EXEC mode.
hostname [hostname]	assign a device name to router.
show interfaces status	provides a summary of the current status of all interfaces on a Cisco switch. This command displays important information about each interface, including: Port: The interface identifier (e.g., Gi1/0/1). Name: The name or description assigned to the interface, if any. Status: The operational status of the interface (e.g., connected, notconnect, err-disabled). Vlan: The VLAN that the interface is assigned to. Duplex: The duplex mode of the interface (e.g., full, half, auto). Speed: The speed of the interface (e.g., 10, 100, 1000 Mbps, auto). Type: The type of interface (e.g., 10/100/1000BaseTX, SFP). This command is useful for quickly assessing the operational state and configuration details of all interfaces on the switch.
clear ip ospf process	used in Cisco IOS to reset or restart the OSPF (Open Shortest Path First) routing process on a router. This command forces the router to reset its OSPF neighbor relationships and rebuild the OSPF topology database, which can be useful for troubleshooting OSPF issues or after making significant configuration changes. Warning: This will temporarily disrupt routing on the OSPF network as the adjacencies are reformed. Be cautious when using this command in a production environment.
show ip ospf interface brief	used to display a summarized view of OSPF interfaces on the router, including key details about each interface’s participation in the OSPF process. This command is helpful for quickly checking the OSPF status of router interfaces without needing the detailed output of other OSPF interface commands.
ip ospf priority <priority_id>	used to set the OSPF (Open Shortest Path First) priority value for a specific interface on a router. This command is critical in influencing the Designated Router (DR) and Backup Designated Router (BDR) elections in OSPF multi-access networks, such as Ethernet.
network 0.0.0.0 255.255.255.255 area <area_id>	Using 0.0.0.0 255.255.255.255 allows for a quick way to enable OSPF on all interfaces without needing to specify each individual interface’s address and mask. All Interfaces Participation: This command is useful in scenarios where you want every OSPF-enabled interface on the router to participate in the OSPF routing process within a specific area.
show ip ospf database	used to display the OSPF link-state database (LSDB) for the router. The LSDB contains information about all OSPF routers and their links within a particular area
show ip ospf	used to display general OSPF information, such as the OSPF process ID, router ID, area configuration, and OSPF timers
router ospf [OSPF ID]	used in networking, specifically in the context of configuring Open Shortest Path First (OSPF) routing on a router
router-id [Router-ID]	used to manually assign a Router ID to a router or routing protocol instance (like OSPF or BGP) within a network
network [ip-address] [wildcard-mask] area [area-id]	This command specifies which interfaces will participate in OSPF and to which area they belong
ip ospf [ospf id] area [area id]	used to configure the OSPF routing protocol on an interface. It specifies which OSPF process (identified by the OSPF ID) will be associated with a particular OSPF area (identified by the area ID) for that interface.
show ip ospf neighbor	used to display information about OSPF neighbor relationships. It provides details about the routers with which an OSPF router has established an adjacency. This command is useful for troubleshooting OSPF neighbor issues and verifying that OSPF adjacencies are forming correctly
show ip ospf neighbor detail	provides more in-depth information about the OSPF neighbors than the basic show ip ospf neighbor command. It displays detailed information on OSPF neighbors and the state of OSPF adjacencies. This command is particularly useful for troubleshooting OSPF neighbor issues and gaining deeper insights into OSPF behavior on a per-neighbor basis.
show ip route	is used on Cisco routers and Layer 3 switches to display the current IP routing table. Here’s what this command provides and its significance: 1. Routing Table: The main purpose of show ip route is to show the IP routing table maintained by the device. This table contains information about networks and subnets that the device knows about and how to reach them. It includes entries for directly connected networks, routes learned dynamically through routing protocols (such as OSPF or EIGRP), and static routes configured manually. 2. Routing Information: Each entry in the routing table typically includes: a. Destination network or subnet (e.g., 192.168.1.0/24) b. Next-hop IP address or exit interface to reach the destination c. Administrative distance (a metric used to determine the reliability of the route) d. Route type (e.g., connected, static, or learned via a routing protocol) e. Metric or cost associated with the route 3. Routing Decisions: The show ip route command helps network administrators troubleshoot connectivity issues and verify the routing paths configured on the device. By examining the routing table, administrators can determine how traffic will be forwarded based on destination IP addresses and make adjustments as needed. 4. Dynamic Updates: If routing protocols are enabled on the device, such as OSPF (Open Shortest Path First) or EIGRP (Enhanced Interior Gateway Routing Protocol), show ip route will display routes learned dynamically from neighboring routers participating in the same routing domain.
description “DESCRIPTION OF SOME SORT”	used to assign a descriptive text label to a network interface on a device such as a router or switch. This description helps administrators to identify the purpose or details of the interface more easily when managing and troubleshooting the network.
show ip interface brief \| include lan	used on Cisco devices to display a summarized list of all IP interfaces configured on the device and filter the output to only show interfaces that contain the keyword “lan” in their configuration. This command is helpful for quickly identifying and troubleshooting interfaces related to LAN (Local Area Network) configurations within the device’s network environment
ipconfig /all	used in Windows operating systems to display detailed information about all network interfaces and their configurations.
no shutdown	enables an interface.
show running-config	save the running configuration to the startup-configuration file.
show running-config \| section interface GigabitEthernet0/*	used to display the configuration details of a specific GigabitEthernet interface (interface GigabitEthernet0/) within the running configuration of a Cisco device. This command allows you to view the configuration settings related to the specified interface only, filtering out other configuration sections. It provides a focused view of the configuration parameters associated with the specified interface, including its IP address, VLAN membership, trunking settings, and any other relevant configuration details. The asterisk (*) is a wildcard character that matches any character or sequence of characters. In this context, it is used to match any subinterface under GigabitEthernet0.
show running-config \| section interface FastEthernet0/1$	The “show running-config \| section interface FastEthernet0/1$” command is similar to the previous one, but it focuses specifically on the FastEthernet0/1 interface. The “$” symbol at the end of the interface name indicates that the command will match only the interface that ends with “FastEthernet0/1”. This command is helpful when you want to view the configuration details of a specific FastEthernet interface without displaying configurations for other interfaces.
copy running-config startup-config	used to save the currently running configuration (stored in the RAM) to the startup configuration (stored in the NVRAM)
end	exit configuration mode.
exit	exits one level in the menu structure command.

Lab Task:

LAN Configurations:
1. On R1, R3, R4 and R5, configure the LAN interfaces with the appropriate IPv4 address settings, interface descriptions, and ensure the interfaces are enabled
2. Configure a virtual loopback interface (0) on each router with the appropriate IPv4 address.
3. Initiate a ping from each end device to its default gateway
4. Perform in-flight checks to verify connectivity
WAN Configuration:
1. On R1 and R2, configure the WAN interfaces with the appropriate IPv4 address settings, interface descriptions, and ensure the interfaces are enabled.
2. Initiate a ping from R1 to R2’s Serial interface IPv4 address. Is the ping successful? If not, troubleshoot and try again.
On R2, R3, R4, and R5 configure interface GigabitEthernet0/0 with the appropriate IPv4 address setting, interface description and enable the interface.
OSPFv2 Configurations:
1. On R1:
  1. Create a new OSPF process with Process ID 1
  2. Enable all interfaces to participate in the OSPF process and assign them to Area 0. Which command should you use?
2. On R2:
  1. Create a new OSPF process with Process ID 2
  2. Enable all interfaces to participate in the OSPF process and assign them to Area 0.
3. On R3:
  1. Create a new OSPF process with Process ID 3
  2. Enable all interfaces to participate in the OSPF process and assign them to Area 0.
4. On R4:
  1. Create a new OSPF process with Process ID 4
  2. Enable all interfaces to participate in the OSPF process and assign them to Area 0.
5. On R5:
  1. Create a new OSPF process with Process ID 5
  2. Enable all interfaces to participate in the OSPF process and assign them to Area 0.
6. Perform in-flight checks:
  1. Ensure that each router is adjacent with the appropriate Router.
  2. Ensure that all routes have been learned by all routers.
  3. Check who is the DR and BDR from the multi-access network.
7. Reset the OSPF process on R2, and confirm which Router is the DR and which Router is the BDR.
8. On each Router do the following:
  1. Issue the appropriate command to determine the state of the OSPF interface.
  2. Issue the appropriate command to verify the OSPF configuration.
Configure manually the Router ID for Router 2 and 3, please use the following Router IDs accordingly:
1. R2: 200.20.20.20
2. R3: 130.30.30.30
3. Perform in-flight checks and verify the OSPFv2 Router-ID on both routers.
Now reset the OSPF process and check which Router is the DR and which Router is the BDR.
Initiate connectivity tests between all end hosts. The ping should be successful. If not, troubleshoot the issue and try again.
Save your configurations.

Lab Solution:

1- LAN Configurations:
a. On R1, R3, R4 and R5, configure the LAN interfaces with the appropriate IPv4 address settings, interface descriptions, and ensure the interfaces are enabled
b. Configure a virtual loopback interface (0) on each router with the appropriate IPv4 address.

On R1:
R1>en
R1#configure terminal
R1(config)#interface gigabitEthernet 0/1
R1(config-if)#description “Link to SW1”
R1(config-if)#ip address 192.168.10.254 255.255.255.0
R1(config-if)#no shutdown

R1(config-if)#interface gigabitEthernet 0/2
R1(config-if)#description “Link to SW2”
R1(config-if)#ip address 192.168.20.254 255.255.255.0
R1(config-if)#no shutdown
R1(config-if)#exit

R1(config)#interface loopback 0
R1(config-if)#ip address 1.1.1.1 255.255.255.255
R1(config-if)#end
R1#

On R2:
R2>en
R2#configure terminal
R2(config)#interface loopback0
R2(config-if)#ip address 2.2.2.2 255.255.255.255
R2(config-if)#end
R2#

On R3:
R3>en
R3#configure terminal
R3(config)#interface gigabitEthernet 0/1
R3(config-if)#description “Link to SW3”
R3(config-if)#ip address 192.168.30.254 255.255.255.0
R3(config-if)#no shutdown
R3(config-if)#exit

R3(config)#interface loopback 0
R3(config-if)#ip address 3.3.3.3 255.255.255.255
R3(config-if)#end
R3#

On R4:
R4>en
R4#configure terminal
R4(config)#interface gigabitEthernet 0/1
R4(config-if)#description “Link to SW4”
R4(config-if)#ip address 192.168.40.254 255.255.255.0
R4(config-if)#no shutdown
R4(config-if)#end

R4(config)#interface loopback 0
R4(config-if)#ip address 4.4.4.4 255.255.255.255
R4(config-if)#end
R4#

On R5:
R5>en
R5#configure terminal
R5(config)#interface gigabitEthernet 0/1
R5(config-if)#description “Link to SW5”
R5(config-if)#ip address 192.168.50.254 255.255.255.0
R5(config-if)#no shutdown
R5(config-if)#exit
R5(config)#interface loopback 0
R5(config-if)#ip address 5.5.5.5 255.255.255.255
R5(config-if)#end
R5#

c. Initiate a ping from each end device to its default gateway

The ping to the default gateway from each device was successful:

d. Perform in-flight checks to verify connectivity

We can issue the “show ip interface brief”:

You can also look at the routing table by issuing the following command “show ip route”:

Please repeat the same commands across all other routers.

2- WAN Configuration:
a. On R1 and R2, configure the WAN interfaces with the appropriate IPv4 address settings, interface descriptions, and ensure the interfaces are enabled.

On R1:
R1#
R1#configure terminal
R1(config)#interface serial 0/3/0
R1(config-if)#description “Link to R2”
R1(config-if)#ip address 10.0.0.1 255.255.255.252
R1(config-if)#end
R1#

On R2:
R2>en
R2#configure terminal
R2(config)#interface serial 0/3/0
R2(config-if)#description “Link to R1”
R2(config-if)#ip address 10.0.0.2 255.255.255.252
R2(config-if)#end
R2#

Perform in-flight checks:

You can see that a new network has been added to the routing table above. Please repeat the same step on R2 and verify your configuration.

b. Initiate a ping from R1 to R2’s Serial interface IPv4 address. Is the ping successful? If not, troubleshoot and try again.

On R1:

You can see that the ping was successful as expected.

3- On R2, R3, R4, and R5 configure interface GigabitEthernet0/0 with the appropriate IPv4 address setting, interface description and enable the interface.

On R2:

R2#
R2#configure terminal
R2(config)#interface gigabitEthernet 0/0
R2(config-if)#description “Link to SW6”
R2(config-if)#ip address 10.10.10.2 255.255.255.248
R2(config-if)#no shut
R2(config-if)#end
R2#

On R3:
R3>en
R3#configure terminal
R3(config-if)#
R3(config-if)#interface gigabitEthernet 0/0
R3(config-if)#description “Link to SW6”
R3(config-if)#ip address 10.10.10.3 255.255.255.248
R3(config-if)#no shut
R3(config-if)#end
R3#

On R4:
R4>en
R4#configure terminal
R4(config)#interface gigabitEthernet 0/0
R4(config-if)#description “Link to SW6”
R4(config-if)#ip address 10.10.10.4 255.255.255.248
R4(config-if)#no shutdown
R4(config-if)#end
R4#

On R5:
R5>en
R5#configure terminal
R5(config)#interface gigabitEthernet 0/0
R5(config-if)#description “Link to SW6”
R5(config-if)#ip address 10.10.10.5 255.255.255.248
R5(config-if)#no shutdown
R5(config-if)#end
R5#

Perform in-flight checks:

You can see from the output above that we are able to ping R3, R4 and R5 from R2.

4- OSPFv2 Configurations:
a. On R1:
1) Create a new OSPF process with Process ID 1
2) Enable all interfaces to participate in the OSPF process and assign them to Area 0. Which command should you use?

R1#
R1#configure ter
R1(config)#router ospf 1
R1(config-router)#network 0.0.0.0 255.255.255.255 area 0
R1(config-router)#end
R1#

b. On R2:
1) Create a new OSPF process with Process ID 2
2) Enable all interfaces to participate in the OSPF process and assign them to Area 0.

R2#
R2#configure terminal
R2(config)#router ospf 2
R2(config-router)#network 0.0.0.0 255.255.255.255 area 0
R2(config-router)#end
R2#

c. On R3:
1) Create a new OSPF process with Process ID 3
2) Enable all interfaces to participate in the OSPF process and assign them to Area 0.

R3#
R3(config)#router ospf 3
R3(config-router)#network 0.0.0.0 255.255.255.255 area 0
R3(config-router)#end
R3#

d. On R4:
1) Create a new OSPF process with Process ID 4
2) Enable all interfaces to participate in the OSPF process and assign them to Area 0.

R4#
R4#configure terminal
R4(config)#router ospf 4
R4(config-router)#network 0.0.0.0 255.255.255.255 area 0
R4(config-router)#end
R4#

e. On R5:
1) Create a new OSPF process with Process ID 5
2) Enable all interfaces to participate in the OSPF process and assign them to Area 0.

R5#
R5#configure terminal
R5(config)#router ospf 5
R5(config-router)#network 0.0.0.0 255.255.255.255 area 0
R5(config-router)#end
R5#

f. Perform in-flight checks:
1) Ensure that each router is adjacent with the appropriate Router.

On R1:

On R2:

On R3:

On R4:

On R5:

2) Ensure that all routes have been learned by all routers.

On R1 we can issue the “show ip route” command:

We can see from the output above that R1 has learnt all networks across the topology.

3) Check who is the DR and BDR from the multi-access network.

We can determine this by issuing the following command on the multi-access network between R2, R3, R4, and R5: show ip ospf interface gigabitEthernet 0/0”:

From the output above, we can see that the Designated Router is R2, as the RID is 2.2.2.2, which corresponds to R2’s loopback interface.

The Backup Designated Router is R3, as the RID for the BDR is 3.3.3.3, which we know belongs to R3’s loopback interface.

g. Reset the OSPF process on R2, and confirm which Router is the DR and which Router is the BDR.

We should use this command to reset the OSPF process, which will trigger the OSPF election process for the DR and BDR:
“clear ip ospf process”

h. On each Router do the following:
1) Issue the appropriate command to determine the state of the OSPF interface.

We can determine from R2 whether each router has formed an adjacency with the appropriate router.

We can also see from the output above that, after resetting the OSPF process, R3 is now the DR, and R5 is the BDR.

2) Issue the appropriate command to verify the OSPF configuration.

We can issue this command for verification:
“show running-config | section router”

5- Configure manually the Router ID for Router 2 and 3, please use the following Router IDs accordingly:
a. R2: 200.20.20.20

R2#
R2#configure terminal
R2(config)#router ospf 2
R2(config-router)#router-id 200.20.20.20
R2(config-router)#end
R2#

b. R3: 130.30.30.30

R3>en
R3#configure terminal
R3(config)#router ospf 3
R3(config-router)#router-id 130.30.30.30
R3(config-router)#end
R3#

c. Perform in-flight checks and verify the OSPFv2 Router-ID on both routers.

We need to issue this command “show ip ospf 2” on R2 to determine the current RID:

On R3 we need to issue this command “show ip ospf 3”:

We can see that even though we changed the RID for both routers, nothing has changed. We must reset the OSPF process for the changes to take effect on both routers.

6- Now reset the OSPF process and check which Router is the DR and which Router is the BDR.

“clear ip ospf process” this command will be issued on R2 and R3:

We can see the RID has changed on R2 as shown below:

The current DR is R2 and the BDR is R3:

7- Initiate connectivity tests between all end hosts. The ping should be successful. If not, troubleshoot the issue and try again.

8- Save your configurations.

Troubleshooting steps:

Here’s a comprehensive list of troubleshooting steps for the lab titled:

LAN Configuration Troubleshooting:
- Check interface status:
  - Use show ip interface brief to ensure that LAN interfaces are up and assigned the correct IP addresses.
  - Ensure that the interface description is set properly with show running-config.
- Verify connectivity between devices:
  - Use ping from the routers and end devices to check connectivity to the default gateway.
  - If a ping fails, check for misconfigured IP addresses or incorrect subnet masks with the show ip interface command.
- Ensure interfaces are enabled:
  - If interfaces are down, use the no shutdown command to enable them.
  - Use show interface to verify the operational status of the interfaces.
WAN Configuration Troubleshooting:
- Verify Serial interface status:
  - Use show ip interface brief to ensure that WAN interfaces are up with the correct IP addresses.
  - Check the encapsulation type with show running-config (typically should be PPP or HDLC). If not configured, use encapsulation ppp or encapsulation hdlc.
- Check clock rate on serial interfaces:
  - Use the show controllers serial command to ensure the clock rate is set on the DCE side. Use clock rate to set the clock rate if required.
- Ping tests:
  - Ping between routers’ serial interfaces to ensure Layer 3 connectivity.
  - If the ping fails, check for any IP address or subnet mask misconfigurations. Correct with ip address .
- Check route entries:
  - Use show ip route to ensure that the routing table includes the connected networks.
OSPF Configuration Troubleshooting:
- Check OSPF Process:
  - Use show ip ospf to ensure that OSPF is running on the router.
  - Ensure that the correct OSPF Process ID is configured with router ospf .
- Verify OSPF Neighbor Relationships:
  - Use show ip ospf neighbor to check if routers have established OSPF neighbor relationships.
  - If a neighbor is missing, check if interfaces are participating in OSPF with show ip ospf interface.
  - Ensure that OSPF is enabled on the correct interfaces and that they are assigned to the appropriate area (e.g., Area 0) with the network command under OSPF configuration.
  - If OSPF adjacencies are not forming, check MTU mismatches with the show interface command.
- Authentication issues:
  - If OSPF authentication is configured, ensure the correct keys are being used. Use show running-config to verify, and set the correct key with ip ospf authentication-key .
Designated Router (DR) and Backup Designated Router (BDR) Troubleshooting:
- Check current DR/BDR status:
  - Use show ip ospf neighbor to check which routers are the DR and BDR.
- Influence DR/BDR election:
  - Ensure the OSPF priority is set correctly on interfaces with ip ospf priority . Higher priority will influence which router becomes the DR.
  - If you need to force an election after configuring the priority, reset the OSPF process with clear ip ospf process.
- Verify DR/BDR election:
  - After resetting the OSPF process, use show ip ospf neighbor to verify the new DR and BDR roles.
Routing Table Verification:
- Check for OSPF routes:
  - Use show ip route ospf to ensure OSPF routes are appearing in the routing table.
  - If routes are missing, ensure that the networks are correctly advertised under OSPF with the network command.
OSPF Neighbor Troubleshooting:
- Ensure interface participation in OSPF:
  - Use show ip ospf interface to check if interfaces are correctly participating in OSPF.
- Check Hello and Dead intervals:
  - Use show ip ospf interface to check if Hello and Dead intervals match on neighboring routers.
  - Use the ip ospf hello-interval and ip ospf dead-interval commands to fix any discrepancies.
Connectivity Tests Troubleshooting:
- Ping test across the network:
  - Use ping to test end-to-end connectivity between end devices. If the ping fails:
    - Check Layer 3 reachability with show ip route.
    - Verify that OSPF is propagating routes properly by using show ip ospf database.
    - Ensure the default gateway is set correctly on the end devices.
- Traceroute test:
  - Use traceroute to ensure the correct path is being taken between devices.
Additional Troubleshooting Commands:
- Debug OSPF:
  - Use debug ip ospf events and debug ip ospf adj to track OSPF event logs and troubleshoot adjacency formation issues.
- Interface verification:
  - Use show interfaces to ensure there are no input/output errors or collisions that might be affecting connectivity.
- Check ACLs:
  - Use show access-lists to check if any ACLs are inadvertently blocking OSPF traffic or ICMP pings.
Restarting OSPF Process:
- If making significant changes to OSPF (like adjusting priorities), it’s often necessary to restart the OSPF process using clear ip ospf process.
Save Configurations:
- Use the write memory or copy running-config startup-config command to ensure all configurations are saved.

Hints and Tips:

Ensure Proper OSPF Area Configuration:
1. All routers participating in OSPF must be in the same area (in this lab, it’s likely to be Area 0, the backbone area).
2. Verify that all routers have the correct OSPF area assigned to their interfaces using the network command.
Check Interface IP Addresses:
1. Ensure that the correct IP addresses are assigned to each router interface. Incorrect IPs can prevent OSPF adjacencies from forming.
2. Use show ip interface brief to verify the interfaces’ IP addresses and status.
Wildcard Mask Configuration:
1. When adding networks to the OSPF process, remember that OSPF uses wildcard masks, which are the inverse of subnet masks. For example, a subnet mask of 255.255.255.0 will have a wildcard mask of 0.0.0.255.
Router IDs Must Be Unique:
1. OSPF Router IDs (RID) must be unique across the network to form adjacencies. If necessary, set the RID manually with the router-id command in OSPF configuration mode.
Check for Mismatched OSPF Timers:
1. Ensure that OSPF hello and dead timers are consistent across adjacent routers. You can check the timer values with show ip ospf interface. If timers are mismatched, OSPF adjacencies won’t form.
OSPF Neighbor State:
1. Verify OSPF adjacencies using show ip ospf neighbor. The state should be FULL for successful adjacencies.
Point-to-Point vs. Broadcast Networks:
1. Make sure OSPF network types are correctly configured based on the topology. For point-to-point links, manually set the network type using the ip ospf network point-to-point command, if necessary.
Ensure No Passive Interfaces:
1. OSPF will not send hello packets on passive interfaces. Check for any interfaces set as passive using the show ip ospf interface command. If needed, remove the passive setting with no passive-interface under OSPF configuration mode.

Conclusion:

In this lab, you have learned how to configure and verify the OSPFv2 Router ID, a critical component for identifying routers within an OSPF domain.

By manually configuring the Router ID, you ensure that OSPF processes can uniquely identify routers and exchange routing information effectively. You also gained experience troubleshooting common OSPF issues related to Router IDs, such as duplicate IDs or adjacency formation problems.

This lab reinforces key OSPF configuration skills that are essential for success in the CCNA 200-301 certification exam.

Packet Tracer Lab (Pre/Post configuration):

Download the file below and open the word document to access the Packet Tracer labs.

CCNA 200-301 Lab Chapter 3 IP Connectivity Lab 035 Configure & Verify OSPFv2 Router ID – Pre and Post Labs Download