ECE 4110 Internetwork Programming Lab 7: Configuring a Network Using RIP Routing Protocol. Prelab Questions

Transcription

1 ECE 4110 Internetwork Programming Lab 7: Configuring a Network Using RIP Routing Protocol Group Number: Member Names: Date Issued: March 26, 2013 Date Due: April 3, 2013 Last Edited: January 31, 2013 This lab requires that you use one of three setups. You must sign up in advance on the lab door. You may reserve one setup for no more than 1.5 hours at a time. You must use the same setup each time you work on this lab. You NEED your group hard drive for this lab. This is a very open ended lab, and you should start early to guarantee you have enough time to finish. Goal In this lab you will become familiar with the Cisco routers and switches in our lab. You will learn to program these routers to create a network, then you will experiment with the routing protocol RIP to observe how routers communicate to make the network functional. Prelab Questions QP.1: What are the differences between a distance vector and a link-state routing protocol? What kind of routing protocol is RIP? QP.2: What IP protocol and port number does RIP use? QP.3: How do RIP routers to exchange routing information? QP.4: What is the maximum number of routes that can be sent in a RIP update? QP.5: What is VLSM? Does RIP support it? Justify your answer. QP.6: What metric does RIP use? 1

2 Lab Scenario In this lab we will construct the network pictured below. (c is either 1, 2, or 3 and is the playstation number your using.) Network 10.c.1.0 Ethernet1 10.c.6.2 Ethernet0 10.c c.6.1 VLAN3 FastEthernet0 RIP1 Digi# Ethernet0 Ethernet1 10.c.2.1 VLAN2 10.c.3.1 VLAN4 Ethernet0 Ethernet0/0 10.c c.3.2 FastEthernet0 Network RIP2 Digi# RIP3 Digi# 10.c c c.7.2 VLAN8 VLAN7 Ethernet1/0 VLAN5 10.c.7.1 Ethernet1 RIP4 Digi# Linux Computer (R3) 10.c.3.3 FastEthernet0/0 10.c.5.1 Network 10.c.5.0 VLAN9 FastEthernet0 10.c.8.1 VLAN6 Network 10.c.8.0 Switch Digi# 2

3 Section 1: Playstation Setup For this lab we have three hardware setups. When you signed up for time in the lab you should have signed up for a particular setup: 1, 2, or 3 (corresponding to c in network diagram as shown in previous page). For the entirety of this lab, c denotes your lab setup number. You should have learned in Lab 5 how to login to the DigiConsole, and configure the Cisco 3550 Switch and 1760 Routers. You will need that knowledge in this since you will be creating the network topology shown in the figure on page 2. You will also need to know how to save your configuration files that you have created on the Switch/Routers. The instructions below describe this: You should have already installed and compiled the mnet_tools_v1.5 package on your group hard drive. If not, see Lab 5 on how to do this. You have the following script commands: # reset_p<number> where the number is the playstation number. will reset the setup. You will need this script at the beginning of this lab or in case you ever need to start over. # download_p<number> will download the current setup to your account hard drive. Run this script at the end of this lab, or if you ever have stop working on the lab. # upload_p<number> will upload your saved configurations to the specified playstation. Use this script if you had to stop working on the lab and wish to continue later on. BEFORE RUNNING ANY OF THESE SCRIPTS MAKE SURE THAT NO OTHER GROUP IS USING THAT SETUP!!! All of these scripts are intended as tools to help you with this lab. Although we have tested them heavily, we are not completely certain that they will function properly every time. We apologize for any problems you may encounter and welcome your input on changes. If you receive ANY messages such as Failed to connect to console manager, run the script again. If a problem persists, contact a TA. Make sure that no one else is using your setup, and then run the reset script. This may take several minutes as we must reset all of our routers. 3

4 Reference the following table to see which devices you will be programming: Playstation1 Playstation2 Playstation3 Switch RIP1 Router RIP2 Router RIP3 Router RIP4 Router By typing the appropriate number, you gain access the router. To log out, type an invalid option, such as q. Go to the router rack at the back of the classroom. The numbers on the console manager and the above table correspond to the numbers posted to the left of the physical routers in this rack. These are the devices you will be configuring. Now by referring to the image on page 2 and the directions you followed in Lab 5, you need to setup the Cisco Router and Switches. You need to create the VLANS, define the Switch interfaces, and configure each router interface. NOTE: DO NOT add static routing like you did in Section 5 of lab 5. This document does not have explicit instructions on how to set this topology up as you learned everything you need to know in Lab 5. The following table should be filled out with information about your setup. Playstation Number: Router Interface VLAN Switch Interface Number RIP1 Ethernet0 RIP1 Ethernet1 RIP1 FastEthernet0 RIP2 Ethernet0 RIP2 Ethernet1 RIP2 FastEthernet0 RIP3 Ethernet0 RIP3 Ethernet1 RIP3 FastEthernet0 RIP4 Ethernet0 RIP4 Ethernet1 RIP4 FastEthernet0 IP Address Table 2.1: Router Interface Table After you are done configuring the switch and routers through the DigiConsole, you will also need to manually configure the networking cables so each router interface plugs into the proper switch ports you have defined. 4

5 Section 2: Configuring RIP on Routers At this point in time, all of our interfaces should be established and running. From RIP4, attempt to ping 10.c.7.1. If you can do this, you can access your own interface. Now attempt to ping 10.c.7.2. This should also be successful; you can now access RIP3 across our functional VLAN! Now try to ping 10.c.3.1. Although a functional link exists between RIP4 and RIP3 and another exists between RIP3 and RIP1, this ping should fail. Routing has not yet been setup on any of our routers, so no router can reach any interface that isn t directly connected! Type show ip route to see what networks your router can currently access. Q2.1: What is the output of this command? What information does this provide? Reenter configuration mode. To enable RIPv4 routing, type: # router rip # version 2 RIP now requires that we tell it to which network it is routing, and to what other routers we are directly connected. Type: # network 10.c.0.0 to advise RIP to route to our entire network. Next configure the neighboring routers by typing: # neighbor 10.c.7.2 # neighbor 10.c.6.2 These are the IP addresses of the directly connected network interfaces of our neighboring routers (see the network diagram). Type exit to leave RIP configuration. Repeat these steps using the appropriate neighbor IPs to configure all four of your RIP routers. Finally our network is configured. After a few minutes the RIP messages will propagate to create all network routes, our network should be fully functional. You may wish to log onto each RIP machine and ping each of the nine router interfaces in order to guarantee that your network is configured properly. If you cannot ping, you may have configured one or more routers incorrectly, and you should fix this problem before moving on to the next section. When troubleshooting, you may want to make use of the show ip route command in order to see which interfaces are not functioning correctly. Log back onto RIP4 and type show ip route again. Q2.2: How has the output changed since you set up RIP? What do these changes mean? 5

6 At this point you need the TA to check off that you can ping various locations on the network. TA CHECK OFF: DATE: Disconnect from the digiconsole. On your Linux machine run the download script on your setup number. Verify that all four configurations were saved to your hard drive. Section 3: Observing RIP Now that we have setup our network, we will look specifically at how RIP responds to changes in the network. Connect to RIP1 and observe the output to the following commands. show ip protocol Q3.1 The output lists several timer values that are associated with RIP. What are these timers? What are their values? What are they used for? show ip route Q3.2.a: Are all the networks indicated in the diagram in the routing table? Q3.2.b: How many routes are there for the network 10.c.8.0/24? Why? Below is an example line from the output of the show ip route command on a different setup. This setup was not using RIP, so your results will be different [110/12] via , Ethernet 0/ is the network for the route [110/12] represents the administrative distance and metric for the route. In this case the administrative distance is 110 and metric is is the IP address of the next-hop router. The next-hop router is the router to which any packet destined for the network should be sent Ethernet 0/0 is the output interface used to send to the next-hop router. Administrative Distance is the trustworthiness of a routing protocol. It is used when there are multiple routing protocols running on a router and 2 or more of them have a route to the same network (same network and mask). The router then chooses the route from the routing protocol that has the lowest administrative distance. 6

7 Q3.2.c: What value is the administrative distance for RIP? Why do you think this is important? Type traceroute 10.c.8.1 When there are multiple routes with the same cost to a destination, routers often use a technique called "equal cost load-balancing". The Cisco routers are configured to alternate which equal cost route is used to send packets. For example, if you send 3 packets and there are 2 equal cost routes, the first packet would go out the first interface, the second packet would go out the second interface, and then the third packet would go out the first interface. Q3.3: Copy your traceroute output below. What path(s) are taken? Include both IPs and the names of the routers. Explain why the output appears as it does. Connect to RIP3, then shutdown the interface Ethernet0/0: #interface Ethernet 0/0 #shutdown Keep track of when you typed shutdown (start a stopwatch if you have one). Because you have changed the network topology, the RIP process on RIP3 will send out an immediate flash update. Note that you have simulated a network failure: interface 10.c.3.2 on RIP3 no longer works. Connect to RIP1, and look at the routing table by typing show ip route. Now type ping 10.c.7.1. You are trying to contact 10.c.7.1 (RIP4) which is on the other side of the shutdown interface of RIP3. Q3.4: Do you get a response? Why/Why not? How long should it take RIP1 to flush its routing tables? Type show ip route on RIP1 again. Q3.5: What routes do you see? Is the routing table different from before? If so, how? If your routing table is unchanged, keep trying until it does change. If you surpass 7 minutes, ask a TA for help. Q3.6: How long did it take the routing table of RIP 1 to change? Why? Type ping 10.c.7.1. Q3.7: Do you now see a response? Why or why not? 7

8 Now try to ping RIP1 from RIP3. On router RIP3 type ping 10.c.3.1. Q3.8: Do you see a response? Why or why not? If it does not work repeat until it does or ask a TA for help. If you did not see a response immediately, how long after you shutdown RIP3 did it take before you could? Why? Re-enable Ethernet0/0 with the no shutdown command. Section 4: Observing RIP Traffic In this section of the lab, you will use Ethereal to examine the updates that are sent between routers. Looking at the network diagram, notice that there is a Linux machine on the subnet between RIP1 and RIP3 labeled Linux Computer (R3). The Linux Computer you will be using is R3, located on the right-most rack by the door. Make sure no other groups are using it. To the left of it you will see a monitor with a pull-out keyboard. This is the terminal you will use to access R3. Above the monitor is a KVM, which is used to share one monitor, keyboard, and mouse among many computers. Push the button labeled R3 to access the box. The network cable from R3 has been run to port 32 of the patch panel at the top of the right-most rack. Coming out of the port labeled 32 should be a long Ethernet cable; this cable is connected to R3 s network card, and is what you will plug into the switch in a port of your choosing. Now, configure that Ethernet port to access VLAN 4 by connecting to the switch and doing the commands: SwitchA# configure terminal <ENTER> SwitchA(config)# interface fastethernet <interface_number> <ENTER> SwitchA(config-if)# switchport mode access <ENTER> SwitchA(config-if)# switchport access vlan 4 <ENTER> Now, open a terminal window on R3. Set the IP of R3 by typing in the terminal: [Prompt]# ifconfig eth0 10.c.3.3 netmask <ENTER> [Prompt]# route add default gw 10.c.3.1 Now, on R3 open Ethereal. Under Display Options enable Automatic scrolling in live capture and disable all three Enable name resolutions. Start capturing packets in promiscuous mode. Let ethereal run for about 2 minutes and then stop capturing packets. Ignore the ARP and TFTP traffic. To save the data captured by Ethereal, you may need to use the procedure as the following: Click File->Print 8

9 Choose "Format" as Plain Text ( PostScript is OK too, if you want to view it with GSview...). Choose "Print to" as File. Type a file name. Choose the style as you need to print. You can save the file in your floppy disk, then open it later with any text editor on another computer. If you have Ethereal in your own PC, simply save the data in a file, then open it with Ethereal. You should see packets originating from two sources, 10.c.3.1 (RIP1) and 10.c.3.2 (RIP3). These are the router updates that are sent from one router to all neighbors. Click on one of the packets originating from 10.c.3.1 and look at the contents of the packet. Answer the following: Q4.1: What is the destination address of IP multicast? What s the significance of this address? Q4.2: What protocol (of transport layer) is used to send RIP updates? Q4.3: What is the source port number? Q4.4: Open the field marked Routing Information Protocol. Do you see where the router s routing table is being sent? Copy what you see under this field and explain what s here. Q4.5: When you look at the ethereal output, the entire routing table is not being sent from RIP1 to RIP3. Why not? Save or take a screenshot of your Ethereal output. Download the playstation configuration to your hard drive again to make sure you have it. Now reset the playstation by running the appropriate reset script. Also, you need to disconnect the network cables you connected earlier. Turn-In Checklist Answer all of the bold questions in this lab, including the prelab questions and the interface table. Print the configurations of your four routers and switch as well as your Ethereal output or screenshot. Take all the information you collected today and write a one to two-page summary (e.g., what did you do, what problems you faced, what did you learn, how do you relate this exercise to the real world, etc). Make sure you justify all of your answers with relevant information from the routers. Here is a check list to help you in the process. Prelab questions and answers. All lab questions and answers (Need to include routing tables) 9

10 Interface Table Router Configuration Files (RIP 1 ~ 4) Ethereal output or screenshot showing the appropriate information A one to two-page summary 10