University of Pittsburgh: School of Information Sciences



University of Pittsburgh: School of Information Sciences

Graduate Program in Telecommunications and Networking

© Copyright 2000 Ryan Walsh, Patrick Dexter, and Joseph Kabara

Modified by Chih-kuang Lin at April/05/2007

Internetworks and Routing 1

IS 1071 Internetworks and Routing.

Version 1.0, Last edited 0.05.2007

Student’s name: ____________________________________

Group Members: ____________________________________

____________________________________

____________________________________

____________________________________

Date of the Experiment: ________________________

Part I: Objective.

The goal of this exercise is to construct a six node TCP/IP network and analyze the use of

RIP vs. OSPF as the active routing protocol.

Part II: Equipment List.

Routers: 3 Cisco 2500 series

2513, 2503, 2501

2 Cisco 7000 series, with Fast Ethernet and Serial boards

Switches: 1 Cisco Catalyst 2820 switch

Other: TFTP server

Terminal

Assorted cabling

Part III: Introduction and Background.

Much like the highway infrastructure, the backbone construction of the Internet presents

an interesting problem: How do you get around? How does packetized data travel from A

to B? Does it get lost? How does it know where is the best or quickest path?

The technological answer behind these questions is called routing. Routing is a

general term used to describe the workings of routers, particularly their manipulation of

packetized data in transit. Routers, combined with hubs and switches, take the traffic of

the Internet, data packets, and attempt to direct it in the most efficient way possible.

A router is a device or software that determines the next network node (or the end

node, meaning the destination machine) to which a packet should be forwarded. The

router is almost always connected to at least two networks. Routers work by forming

routing tables, general tables of information on how the traffic should be directed, and

sending out this information to other routers on the network. (The exact method of

sending is implementation-dependant.)

A hub is a place where data arrives from one or more directions and is forwarded

out in one or more other directions. A hub usually includes a switch of some kind, or the

switch could be housed as a separate unit. The distinction seems to be that in the switch

many can talk at once, all at the same speed, while in the hub, only one can speak at a

time. If more than one node is speaking at a time, collisions occur. When using

CSMA/CD, backoffs are a method for avoiding these collisions. After a collision is

detected, the one of the colliding systems “backs off” from sending for a length of time

(variable or fixed), while the other sender attempts to resend.

These devices all work together to form our picture of the Internet, and in this

experiment, you will be manipulating some of these components to implement your own

network and form conclusions about how routing works in relation to this network.

The hardware we will be using in this lab includes Cisco routers, both 7000 and

2500 series, and a Cisco catalyst 2820 switch. The Cisco 2500 series of Ethernet and

token ring routers provide connectivity and routing for smaller enterprises. Alternatively,

the Cisco 7000 provides a more expandable routing solution with removable boards of

interfaces. The 2820 switch connects the two, and any other networking components, via

software configurable virtual LANs on any of the ports on the switch.

The software we will be using in this lab includes the Cisco Internetwork

Operating System (IOS), which is the text-based operating system for Cisco routers. We

will be dealing with two flavors of the IOS, one for the routers, which has a Unix-like

command line, and one for the catalyst switch which utilizes a menu system for

configuration.

Part IV: Lab Procedures.

The goal of this lab is to construct a 6-node IP network that will utilize two methods of

routing, RIP and OSPF. RIP (routing information protocol) is a routing protocol that

utilizes regular broadcasts of the routing table to keep all routing nodes up to date.

Routing is determined by hop count. OSPF (open shortest path first) is a more

encompassing solution, which utilizes any number of conditions (called metrics) to

determine which path to destination is the “open shortest path.” Examples of metrics

include cost and line speed.

Before coming to lab you should first sketch a diagram of the network you will be

constructing. This is essential to a properly configured network, as planning is necessary

and primary. Our goals are two separate paths to the interface address 192.168.26.1. We

will go through the networks 192.168.50.0, 192.168.30.0, 192.168.24.0, 192.168.99.0,

and 192.168.20.0.

Configuring the interfaces

First, we must user router commands to setup our chosen routes. You will be interfacing

with each of the devices separately, and issuing commands that will establish routes on

our practice network, with each hop having a certain line speed, IP address, and port type

and number associated with it.

In order to see the difference between the RIP and OSPF routing protocols, we

will setup two paths: one having more hops but higher bandwidth, and the other having

less hops but smaller bandwidth.

Path 1

This path has more hops but higher bandwidth than Path 2. To setup the logical

links between the machines, a set of commands will be necessary for each side of each

link. Once you learn how to issue the commands to one device, it will be a simple matter

to repeat the steps on all the devices. The following sequence will walk you through steps

required to setup the connection of the first device:

1. Establish a connection with the Cisco router (exactly how this is done will vary

and should be given on an updates page or by the GSA responsible for this lab). Your

prompt should look something like this:

C>

2. Issue the following commands:

C>enable [CR]

C>password: password [CR]

C#configure terminal [CR]

C(config)#interface ethernet1 [CR]

C(config-if)#ip address 192.168.50.2 255.255.255.0 [CR]

C(config-if)#no shutdown

C(config-if)#[Ctrl-Z]

3. Now setup the rest of the links. The entries that come after the interface command

will change, as well as the IP address that comes after the ip address command, and so

these are given for each link to be created in the following table (note the link we just

setup is included for completeness):

[pic]

(note that cisco 2514 is not used in this lab so no need to configure that machine)

Since the Cisco 7000-2 and the Cisco 2513 routers are both plugged into a Catalyst

switch, we now want to put those two links on their own virtual LAN (VLAN) so that

they are logically linked and can reach one another. In this lab, use the VLAN 2 ports (9-16) on 2800-2 catalyst.

Since we want Path 1 has a higher bandwidth, we will manually set up the serial link

between C2503 and C7000-1 to have a clock rate of 64000 bps. This is done by issuing

the following command at the router C7000-1. Configure the serial1/2 port at C7000-1:

C7000-1(config-if) #clock rate 64000 [CR]

You do not need to configure the other side of the serial link.

Path 2

This path runs through fewer hops but over a slower line. The following table contains

the interfaces and IP addresses used for each link. The commands are issued in the same

way as was described above. The only difference here it that we will manually slow down

the serial links to having a clock rate of 9600 bps. That is done by first setting up the link

as described above the n issuing the following command at the proper prompt. Go to

C2511 serial0 port, configure it at the proper prompt:

C2511(config-if)#clock rate 9600 [CR]

Then go to C serial0 port, configure it at the proper prompt:

C2513(config-if)#clock rate 9600 [CR]

|Device |Interface |IP address |

|2511 |Serial1 |192.168.24.1/8 |

|2511 |Serial0 |192.168.26.2/8 |

|2511 |Ethernet0 |192.168.30.3/8 |

|2513 |Serial1 |192.168.26.1/8 |

|2513 |Serial0 |192.168.26.4/8 |

Configuring RIP Routing

Now we will enable RIP routing on each device we have just configured. To do this issue

the following commands:

C>enable password [CR]

C# show run

Browse the screen, and if you find a configuration of OSPF like the following:

OSPF xxx (xxx is the process id assigned to the OSPF),

then type the following commands at the prompt:

C#configure terminal [CR]

C(config)#no router ospf xxx

If no OSPF configuration is found, only issue the following command:

C#configure terminal [CR]

Then, go on to configure the RIP protocol.

C(config)#router rip [CR]

C(config-router)#network network-number [CR]

C(config-router)#network network-number [CR]

C(config-router)#network network-number [CR]

.

.

.

You can add as many networks as you want using this method. Now, go to each device

and add the networks that are given in the table below:

[pic]

[pic]

Afterwards, view the routing tables for the Cisco 2503 and Cisco 2513 devices by

executing the show IP route command, and fill in the following tables:

Cisco 2513:

|Destination IP address |interface |Source of information |Protocol |metric |

| | | | | |

| | | | | |

| | | | | |

Cisco 2503:

|Destination IP address |interface |Source of information |Protocol |metric |

| | | | | |

| | | | | |

| | | | | |

Now execute the traceroute command on the IP addresses of the end nodes to determine

transmit time and speed, and fill in the following tables. The syntax for this command is:

traceroute IP-address [CR]

[pic]

Confidence Interval Equation.

[pic]

Now, turn off RIP, turn on OSPF, configure, and view the routing table. The following

sequence of commands gives the proper syntax:

C#show process [CR] [pick a number (process- id) larger than the current

processes]

C#configure terminal [CR]

C(config)#no router rip [CR]

C(config)#router ospf process-id [CR]

C(config-router)#network network-number mask area area-id [CR]

C(config-router)#

The network-number identifies the network using ospf, the mask tells which bits to use

from the network-number, and the area-id is used for determining the different ‘areas’ in

an ospf configuration. (use: 0.0.0.0). Execute this sequence of commands at each device

using the settings given in the table below.

[pic]

From the Cisco and Cisco 2513 devices, issue the show ip route command and fill

in the following tables:

Cisco 2513:

|Destination IP address |interface |Source of information |Protocol |metric |

| | | | | |

| | | | | |

| | | | | |

Cisco2503 :

|Destination IP address |interface |Source of information |Protocol |metric |

| | | | | |

| | | | | |

| | | | | |

Now execute the traceroute command on the IP addresses of the end nodes to determine

transmit time and speed, and fill in the following tables.

Traceroutes IP-address

Traceroute 192.168.24.1

[pic]

Part V: Questions

1. Can you account for the differences between what you saw in the ping times when

RIP as opposed to OSPF was the active routing protocol?

2. Draw the network diagram to include both of path #1 and path #2.

Setup procedure

1. Connections.

a 2503: Connect ethernet0 to port 14 of catalyst 2820.

connect serial0 to serial1/2 of 7000-1.

b 7000-1: Connect fastethernet0/1 with fastethernet0/0 of 7000-2.

(via wall)

c 7000-2: Connect ethernet1/0 with port 12 of the catalyst.

d 2511: Connect ethernet0 with port 11 on the catalyst.

e 2513: Connect ethernet0 with port 10 on the catalyst.

Connect serial0 with 2511’s serial0.

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