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Transcript
ECE 4110 Internetwork Programming
Lab 7: Configuring a Network Using RIP Routing Protocol
Group Number: _________________________
Member Names: _________________________
_________________________
Date Issued: October 23, 2008
Date Due: October 29, 2008
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 do RIP use?
QP.3: How do RIP routers 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?
Lab Scenario
1
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
VLAN3
Switch 0/__
10.c.1.1
FastEthernet0
RIP1 Digi#__
Switch 0/__
Ethernet0
10.c.2.1
VLAN2
Ethernet1
Switch 0/__
10.c.3.1
Linux
Computer
(R3)
10.c.3.3 Switch 0/__
VLAN4
Switch 0/__
Ethernet0 10.c.2.2
10.c.3.2 Ethernet0/0
Switch 0/__
Switch 0/__
Switch 0/__
FastEthernet0
FastEthernet0/0
Network
Network
RIP2 Digi#__ RIP3 Digi# __
10.c.4.0
10.c.5.1
10.c.5.0
10.c.4.1
10.c.7.2
Switch 0/__
Ethernet1 10.c.6.2
Ethernet1/0
VLAN8
VLAN9
VLAN5
Switch 0/__
10.c.6.1 10.c.7.1
VLAN7
Switch 0/__
Switch 0/__
Ethernet1
Ethernet0
RIP4 Digi#___
FastEthernet0
Switch 0/__
10.c.8.1
VLAN6
Network 10.c.8.0
Switch Digi#_____
2
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
Reference the following table to see which devices you will be programming:
Switch
RIP1 Router
RIP2 Router
RIP3 Router
RIP4 Router
Playstation1
5
7
8
9
10
Playstation2
14
16
17
18
19
Playstation3
23
25
26
27
28
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
IP Address
RIP1 Ethernet0
RIP1 Ethernet1
RIP1 FastEthernet0
RIP2 Ethernet0
RIP2 Ethernet1
RIP2 FastEthernet0
RIP3 Ethernet0
RIP3 Ethernet1
RIP3 FastEthernet0
RIP4 Ethernet0
RIP4 Ethernet1
RIP4 FastEthernet0
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
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 RIPv2 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
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.
10.11.3.0 [110/12] via 10.1.2.2, Ethernet 0/0
10.11.3.0 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 12
10.1.2.2 is the IP address of the next-hop router. The next-hop router is the
router to which any packet destined for the network 10.1.3.0 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
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
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 255.255.255.0 <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
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




Interface Table
Router Configuration Files (RIP 1 ~ 4)
Ethereal output or screenshot showing the appropriate information
A one to two-page summary
10