Monavathia's Blog

CCNA 3 Labskill Chapter 6

Posted on: December 23, 2010

Lab 6.3.2 Configuring OSPF Summarization

Step 1: Connect the equipment

  1. Connect Router 1 to Routers 2 and 3 with serial cables. Connect Router 2 to Router 3 with a serial cable.
  2. Connect the Router 2 Fa0/0 interface to the Switch 2 Fa0/1 interface using a straight-through cable.
  3. Connect the Router 3 Fa0/0 interface to the Switch 3 Fa0/1 interface using a straight-through cable.
  4. Connect Host 2 to Switch 2 and Host 3 to Switch 3 to the Fa0/2 interface using straight-through cables.
  5. Connect Host 1 to the Router 1 Fa0/0 interface using a crossover cable.
  6. Connect a PC with a console cable to perform configurations on the routers and switches.

Step 2: Perform basic configurations on the routers

  1. Establish a console session with Router 1 and configure hostname, passwords, and interfaces as shown in the addressing table. Save the configuration.
  2. Establish a console session with Router 2. Configure hostname, passwords, and interfaces according to the addressing table. Save the configuration.
  3. Establish a console session with Router 3. Configure hostname, passwords, and interfaces according to the addressing table. Save the configuration.

Step 3: Perform basic configurations on the switches

  1. Establish a console session with Switch 2 and configure hostname and passwords according to the addressing table. Save the configuration.
  2. Perform a similar configuration on Switch 3, configuring the hostname and passwords as described for SW 2. Save the configuration.

Step 4: Configure the hosts with the proper IP address, subnet mask, and default gateway

  1. Configure each host with the proper IP address, subnet mask, and default gateway for the network on which it resides. Host 1 should be assigned the address 209.165.201.1/24. Host 2 and Host 3 should be assigned IP addresses in the 192.168.10.0/28 and 192.168.10.32/28 networks respectively. All three PCs use the Fa0/0 interface of their attached router as their default gateway.
  2. Each workstation should be able to ping the attached router. If the ping is not successful, troubleshoot as necessary. Check and verify that the workstation has been assigned the correct IP address and default gateway.

Step 5: Configure OSPF routing with default summarization

  1. On Border, configure OSPF as the routing protocol with a process ID of 1 and advertise the appropriate networks.
  2. Perform a similar configuration on R2, using the same process ID and advertising the appropriate networks. Remember to advertise the FastEthernet interface.
  3. On R3, perform a similar configuration, using the same process ID and advertising the appropriate networks.

Step 6: Configure and redistribute a default route for Internet access

  1. From the Border router to Host 1, the host simulating the Internet, create a static route to network 0.0.0.0 0.0.0.0, using the ip route command and the next hop interface. This will forward any unknown-destination address traffic to the PC simulating the Internet by setting a gateway of last resort on the Border router.
  2. Border will advertise this route to the other routers if this command is added to its OSPF configuration.

Border(config)#router ospf 1

Border(config-router)#default-information originate

Step 7: Verify the routing configuration

  1. View the routing table on Border.
  2. View the routing tables on R2 and R3.

How is the pathway for Internet traffic provided in their routing tables? There is a gateway of last resort leading to R3, and the default route shows up as a distributed OSPF route.

Step 8: Verify connectivity

  1. Simulate sending traffic to the Internet by pinging from the host PCs to 209.165.201.1.

Were the pings successful? __________ Yes.

Verify that hosts within the subnetted network can reach each other by pinging between Host 1 and Host 2.

Were the pings successful? __________ Yes.

Step 9: Configure OSPF summarization

  1. Compute a summary route for the corporate subnetworks. The networks have been assigned contiguously:
  2. Configure the summary route in router configuration mode, starting with area 0 range followed by the summary route and its mask.

Step 10: Recheck routing tables to verify the summarization

View the effects of summarization using the following commands: Think about your answers to the previous questions. What advantage do you see in using summarization in this network? Jawaban: This makes the job of the Border router simpler and easier, as it can represent the whole network with one route. The ISP does not care about individual subnets; its job is simply to provide Internet access to the area. Convergence will be improved, as Border will not have to issue updates on every problem on every subnet.

Step 11: Reflection

List three effects of using summarization within an OSPF area? Jawaban: smaller routing table, lower memory and processor requirements, fewer lookups needed.

Lab 6.3.1 Configuring and Propagating an OSPF Default Route

Step 1: Connect the equipment

Connect each of the routers, switches, and hosts as shown in the topology diagram.

Step 2: Perform basic configurations on the routers

  1. Connect a PC to the console port of the router to perform configurations using a terminal emulation program.
  2. On Routers 1, 2, and 3, configure the hostname, console, Telnet, privileged passwords, and message-of-the-day banner and disable DNS lookups according to the addressing table and topology diagram.

Step 3: Configure the ISP router

  1. Configure serial and loopback interfaces on Router 3.
  2. On Router 3, configure a default route to both the 192.168.0.0 and the 192.168.1.0 networks.

Step 4: Configure the Area 0 OSPF routers

  1. Configure loopback, FastEthernet, and serial interfaces on Router 1 and Router 2.
  2. Save the running configuration to the NVRAM of each router.

Step 5: Configure the hosts with the proper IP address, subnet mask, and default gateway

Each workstation should be able to ping the attached router. Troubleshoot as necessary. Remember to assign a specific IP address and default gateway to the workstation. At this point, the workstations will not be able to communicate with each other.

Step 6: Verify connectivity

Ping from R2 to both the ISP and R1 routers. Were the pings successful? Jawaban: yes

Step 7: Configure OSPF routing on both Area 0 routers

  1. Configure OSPF routing on each router. Use OSPF process number 1 and ensure that all networks are in Area 0.

Step 8: Test network connectivity

Ping the R1 host from the R2 host. Was it successful? Jawaban: yes

Step 9: Observe OSPF traffic

  1. At the privileged EXEC mode, enter the command debug ip ospf events and observe the output. You may have to wait at least 40 seconds for the hello packet to be sent before observations can be recorded
  2. Turn off debugging by entering no debug ip ospf events or undebug all.

Step 10: Create a default route to the ISP

On R2 only, enter a static default route.

R2(config)#ip route 0.0.0.0 0.0.0.0 200.20.20.1

Step 11: Verify the default static route

Verify the default static route by looking at the R2 routing table.

Step 12: Verify connectivity from the R2 router

  1. Verify connectivity from R2 by pinging the ISP Serial 0/0/1 interface from the R2 router.

Is the ping successful? __________ yes

  1. Next, on the host attached to R2, open a command prompt and ping the Serial 1 interface on the ISP router.

Is the ping successful? __________ yes

  1. This time, ping the loopback interface address of the ISP router, which represents the ISP connection to the Internet.

Step 13: Verify connectivity from the R1 router.

Verify the connection between the ISP and R1 by pinging the Serial 0/0/1 interface of the ISP router on R2.

Step 14: Redistribute the static default route

Propagate the gateway of last resort to the other routers in the OSPF domain. At the configure router prompt on R2, enter default-information originate.

R2(config-router)#default-information originate

Step 15: Reflection

  1. How does OSPF reach networks outside of the domain? Jawaban: OSPF must know about the network or OSPF must have a default route.
  2. What does a router use to generate a gateway of last resort? Jawaban: Default route.

Lab 6.2.4 Part B: Configuring and Verifying Multi-access OSPF

Step 1: Connect the equipment

Connect the Fa0/0 interface of each router to the switch using a straight-through cable. Three routers are sharing a common Ethernet multi-access network, 192.168.1.0/24. Each router will be configured with an IP address on the FastEthernet interface and a loopback address for the router ID.

Step 2: Perform basic configurations on the routers

Step 3: Configure and activate Ethernet and Loopback addresses

Step 4: Verify IP addressing and interfaces

  1. Use the show ip interface brief or the show protocols command to verify that the IP addressing is correct and that the interfaces are active.
  2. After all interfaces are verified, be sure to save the running configuration to the NVRAM of the router.

Step 5: Configure OSPF on the DR router

The DR and BDR election process takes place as soon as the first router has its interface enabled for OSPF on the multi-access network. If OSPF is already configured for an interface, this can happen as the routers are powered on.

Step 6: Configure OSPF on the BDR router

  1. Configure the OSPF process on the router with the second highest router ID to ensure that this router becomes the BDR. Use the router ospf command in global configuration mode to enable OSPF on the R2 router.  What console message was displayed as a result of the OSPF commands on R2 and what does this mean? Jawaban: An OSPF adjacency message displayed indicating an adjacency was formed with the R3 router (Nbr 192,168.31.33). When the hello packet is received, the neighbor relationship is formed.

00:08:51: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.31.33 on

FastEthernet0/0 from LOADING to FULL, Loading Done

  1. Use the show ip ospf interface command to verify that the OSPF has been configured correctly and that R2 is the BDR.

Step 7: Configure OSPF on the DRother router

  1. Configure the OSPF process on the router with the lowest router ID last. This router will be designated as DRother instead of DR or BDR. Use the router ospf command in global configuration mode to enable OSPF on the R1 router
  2. Use the show ip ospf interface command to verify that the OSPF has been configured correctly and that R1 is a DRother.

Step 8: Use the OSPF priority to determine the DR and BDR

  1. Use the ip ospf priority interface command to change the OSPF priority of the R1 router to 255. This is the highest possible priority.
  2. Use the ip ospf priority interface command to change the OSPF priority of the R3 router to 100.
  3. Use the ip ospf priority interface command to change the OSPF priority of the R2 router to 0. A priority of 0 causes the router to be ineligible to participate in an OSPF election and become a DR or BDR.
  4. Shut down and re-enable the FastEthernet0/0 interfaces to force an OSPF election. As the interfaces are shut down, the OSPF adjacencies are lost.

Step 9: Reflection

  1. When the OSPF process starts, what happens if there is no active interface on the router? Jawaban: OSPF will not start.
  2. What can be done to ensure there will be an active interface on a router? Jawaban: Configure a loopback interface.
  3. How are the DR and BDR elected in an OSPF network? Jawaban: The DR is chosen with the highest OSPF priority value. The BDR is chosen with the second highest priority value. If the priority is the same, the OSPF election for DR is decided on the highest Router ID.
  4. What OSPF interface priority value prevents a router from being elected as a DR? jawaban: 0

Lab 6.2.4 Part A: Configuring and Verifying Point-to-Point OSPF

Step 1: Connect the equipment

  1. Connect the Fa0/0 interface of each router to the Fa0/1 interface of each switch using a straightthrough cable.
  2. Connect each host to the Fa0/2 switch port of each switch using a straight-through cable.
  3. Connect serial cables from each router to the other router as shown in the topology.

Step 2: Perform basic configurations on the routers

  1. Connect a PC to the console port of the router to perform configurations using a terminal emulation program.
  2. On all routers, configure the hostname, passwords, and message-of-the-day banner and disable DNS lookups according to the addressing table and topology diagram.

Step 3: Configure the router interfaces

Step 4: Verify IP addressing and interfaces

  1. Use the show ip interface brief or the show protocols command to verify that the IP addressing is correct and that the interfaces are active.
  2. After all interfaces are verified, be sure to save the running configuration to the NVRAM of the router.

Step 5: Configure Ethernet interfaces of PC1, PC2, and PC3

  1. Configure the Ethernet interfaces of PC1, PC2, and PC3 with the IP addresses and default gateways from the addressing table.
  2. Test the PC configuration by pinging the default gateway from each PC.

Step 6: Configure OSPF on Router 1

  1. Configure OSPF on the R1 router. Enter a process ID of 1 for the process-ID parameter. R1(config)#router ospf 1
  2. Configure the network statement for the LAN. When you are in the Router OSPF configuration submode, configure the LAN 172.16.1.16/28 to be included in the OSPF updates that are sent out of R1. Use an area ID of 0 for the OSPF area-id parameter. Zero will be used for the OSPF area ID in all network statements in this topology.

R1(config-router)#network 172.16.1.16 0.0.0.15 area 0

  1. Configure the router to advertise the 192.168.10.0/30 network attached to the Serial 0/0/0 interface.

R1(config-router)#network 192.168.10.0 0.0.0.3 area 0

  1. Configure the router to advertise the 192.168.10.4/30 network attached to the Serial 0/0/1 interface. R1(config-router)#network 192.168.10.4 0.0.0.3 area 0
  2. Return to privileged EXEC mode and save the configuration.

Step 7: Configure OSPF on the R2 router

  1. Enable OSPF routing on the R2 router using the router ospf command. Use a process ID of 1.

R2(config)#router ospf 1

  1. 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

Step 8: Configure OSPF on the R3 router

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.

Step 9: Configure OSPF router IDs

  1. 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:
  2. Examine the current router IDs in the topology.
  3. The router ID can also be seen in the output of the show ip protocols, show ip ospf, and show ip ospf interfaces commands.

Step 10: Verify OSPF operation

  1. On the R1 router, use the show ip ospf neighbor command to view the information about the
  2. On the R1 router, use the show ip protocols command to view information about the routing protocol operation.

Step 11: 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.

Step 12: Configure OSPF cost

  1. Use the show ip route command on the R1 router to view the OSPF cost to reach the 10.10.10.0/24 network.
  2. Use the show interfaces serial0/0/0 command on the R1 router to view the bandwidth of the Serial 0/0/0 interface.

Step 13: Reflection

What are some advantages of using OSPF as a routing protocol? Jawaban: supports VLSM and CIDR, uses cost metrics to choose the best path, and each router has a complete picture of the entire network.

 

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