Lab 4   Dynamic Routing with RIP

Due Dec 6,2007

topology.jpg


PART 1

 

Before you start, please reboot the PCs so that you don’t have old configuration issues. 
Be very careful to follow the directions in this writeup.  Do not change any of the passwords for any of the devices!  For all of the machines, MAKE NOTE OF THE CURRENT SETTINGS SO THAT AT THE END OF THE LAB YOU CAN RECONFIGURE THE MACHINES TO THEIR ORIGINAL VALUES!

In this lab we will configure the routers to use dynamic routing using the RIP protocol.  Connect the PCs and routers according to the figure above.   As usual, you can log into the PCs using root as the user name and netlab as the password.  Do not change the password!

Configure the PC interfaces with an appropriate IP address for the network the interface is attached (e.g. PC4 may be 10.0.4.1). Set up the interfaces as you did in the last lab by using the

PC4% ifconfig <int> <address/mask>

In addition, set the default route for each Linux box so that it knows what address to send packets that are destined for other networks. Since each box is attached to only one router, we can simply set a default route in the Linux box to send messages to the router address that is on its network.  To do this, you use the route command (do a man route to see details). The command is used as:

route add default gw <router_address>

Use the blue serial cable as last time to hook up each router to to a PC and configure the router.

Open up minicom on the appropriate PC and go to the enable mode to configure the router.

Router1>  enable
Password: cisco80211
Router1#

As in the last lab, you can enter a question mark to see what commands are available.

Some commands that you might use include:

Router1# configure terminal
Router1(config)#

Router1(config)# interface FastEthernet0/0 
Router1(config-if)#

To return from the interface configuration to the global configuration or from the global configuration to the Privileged EXEC mode, use the exit command.

Router1(config-if)# exit
Router1(config)# exit
Router1#

When you have finished configuring the interfaces, use the commands to assure that the configuration is correct.

Router1# show interfaces
Router1# show running-config

Now set the routers up to run the RIP protocol:

On Router1, this would be done as follows:

Router1# configure terminal

The no ip routing disables IP forwarding and resets the contents of the routing  table. The ip routing command enables ip forwarding on the route.

 Router1(config)# no ip routing                
Router1(config)# ip routing                       
Router1(config)# router rip                         //enables the RIP protocol and enters router-config mode

Router1(config-router)# version 2           //Sets RIP to use RIPv2
Router1(config-router)# network 10.0.0.0 

//Associates IP address with RIP.  RIP will send updates only on interfaces on which network address has been associated with RIP

Router1(config-router)# interface FastEthernet0/0
Router1(config-if)# no shutdown
Router1(config-if)# ip address 10.0.0.254 255.255.255.0

Configure the other interface similarly.

Then finish with:

Router1(config-if)# end
Router1# clear ip route *

Do the same with Router2 and Router 4

After you have configured the routers check the routing table at each router by typing

Router1# show ip route

Each router should have 4 entries in the routing table: two entries for directly connected networks and two other entries for remote networks that were added by RIP.  Attach the tables for Router2  and Router4 to your report  along with a brief explanation.

Confirm that you can successfully ping every Linux PC from each Linux PC.  Finally run a traceroute on PC1 to PC4

PC1% traceroute <PC4 address>

Save the results of your traceroute to a file and attach it to your report with an explanation.

Start wireshark on all of the PCs and capture packets.   (See if you can filter to capture only RIP packets).  Use the results of your capture to answer the following questions.  In your report, attach appropriate data to support your answer.

1.       What is the destination IP address of RIP packets?

2.       Do routers forward RIP packets? (e.g. does PC1 receive RIP  packets from PC4?)

3.       What types of routing RIP messages do you observe? The type is indicated by the value in the field command.  What role does each message type play?

4.       Describe the information that you find in a RIP message.  How many bytes does each routing table entry take? 

 

PART 2

 

Updating Routing Tables

On Router1, bring down the interface that is connected to 10.0.1.0/24.  Disconnect Router 1 from network 10.0.1.0/24 and connect it to network 10.0.4.0/24.  Reconfigure the interface for router1 and make sure that it is again running RIP.  Compare the routing tables of Router2and Router4 with the previous tables.  Explain any changes, or if there are no changes, explain why not. 

 

Finally change the gateway router for PC4 to be Router1 instead of Router4. 

 

Convergences after Link Failure

 

Start wireshark on PC3 and capture packets

Issue a ping command from PC4 to PC2 but do not terminate until instructed.

PC4% ping <PC2 address>

Save the ping data from the terminal screen.

 

Disconnect Router1 form the 10.0.2 network by unplugging the Ethernet cable from the router.

Wait until the ping command is successful again – that is when reply messages come back to PC4.

Stop the ping command with Ctrl-C. Estimate the amount of time it took before the routing tables were updated. (either by counting ping packets, ~1/second, or by use of the wireshark data)  Include your answer and how you determined it.

 

Return the lab to its original state and clear any files that you may have created.