List of Experiments Course Title: Computer Network Lab Course Code-ETE 332 Experiment No
Experiment Title
1
Orientation With Packet Tracer
2
Client Server Interaction
3
Topology Orientation and Building a Small Network
4
UDP and TCP port numbers
5
Observing TCP Session Establishment and TCP Session Termination
06
Router Packet Forwarding
07
Observing Dynamic Routing Protocol Updates
08
Simple Wireless LAN Model
09
Building a LAN LAN using a Category 5 Cable
ETE 332: Computer Network Lab Experiment No-01: Orientation with Packet Tracer Introduction: Packet Tracer is a network simulator that allows you create a simulated network, configure the devices in the network, test the network, and examine the traffic in the network. The first step in creating a simulated network in Packet Tracer is to place the devices in the logical workplace and connect them together. Packet Tracer uses the same symbols as are used throughout the curriculum. Match the icons in PT with the symbols in the symbol list.
Objectives: 1. Explore the PT interface • Locate the key components used to place device symbols in the logical workplace • Examine the devices that can be placed in the logical workplace and their symbols 2. Place and connect devices • Add device symbols to the logical workplace • Connecting devices in the logical workplace using auto connection
Task 1: Explore the PT interface Step 1 – Logical Workplace
When Packet Tracer starts, it presents a logical view of the network in real-time mode. The main part of the PT interface is the Logical Workplace. This is the large blank area where devices can be placed and connected. Step 2 – Device Symbols
The lower left portion of the PT interface, below the yellow bar, is the portion of the interface that you use to select and place devices into the logical workplace. The first box in the lower left contains symbols that represent groups of devices. As you move the mouse pointer over these symbols, the name of the group appears in the text box in the center. When you click on one of these symbols, the specific devices in the group appear in the box to the right. As you point to the specific devices, a description of the device appears in the text box below the specific devices. Click on each of the groups and study the various devices that are available and their symbols.
Task 2: Add devices to the logical workplace Step 1 – Selecting and placing devices
To add a device to the logical workplace click on the specific device symbol, point to where you want to place the device in the logical workplace (the pointer becomes a crosshair), and click. Locate and place the following devices in a horizontal row across the logical workplace, with about an inch between them, in order from left to right:
a server a 2960 switch an 1841 router a hub an IP phone a PC
Step 2 – Connect the devices using auto connect
Click on the connections group symbol. The specific connection symbols provide different cable types that can be used to connect devices. The first specific type, the gold lightning bolt, will automatically select the connection type based on the interfaces available on the devices. When you click on this symbol, the pointer resembles a cable connector. To connect two devices click the auto connection symbol, click the first device, and then click the second device. Starting with the server, connect each device to the device to its right using the auto connection symbol. Step 3 - Packet Tracer Scoring
Packet Tracer activities can be configured to score your work. To check your configuration, click the Check Results button below.
Experiment No-02 Client-Server Interaction Introduction: Clients, such as desktop PCs, request services from servers. The course lab environment, using actual PCs and servers, supports a full range of services. In a simulated environment, the number of services is limited. Packet Tracer allows the addition of simulated network servers that support DHCP, DNS, HTTP, and TFTP. Packet Tracer also supports the addition of simulated PCs that can request these services. This activity uses a simple network consisting of a PC connected directly to a server configured to supply DNS services and hosting a web page. The activity will track the flow of traffic when a web page is requested, the IP address of the web page is resolved and the web page is delivered.
Objectives: 1. Setup and run the simulation • Enter simulation mode • Set Event List Filters • Request a web page from the PC • Run the simulation 2. Examine the results • Access a specific PDU • Examine the contents of the PDU Information Window
Task 1: Setup and run the simulation Step 1 – Enter simulation mode
When Packet Tracer starts, it presents a logical view of the network in realtime mode. At the end of the yellow bar below the logical workplace is the Realtime tab. Behind and to the right of the Realtime tab is the Simulation tab. Click this tab to enter simulation mode. Step 2 – Set Event List Filters In simulation mode, the default is to capture all events supported by Packet Tracer. You can limit what is captured by setting event list filters. We want to capture only DNS and HTTP events. In the Event List Filters section, click the Edit Filters button. A list of available events is displayed with all of them selected. Click the check box to the left of Show All/None in the lower right. All of the checks are cleared. Click the check box to the left of DNS and HTTP to select only DNS and HTTP events. Click outside of the events window to close it. The Event List Filters shows DNS and HTTP as the only visible events.
Step 3 – Request a web page from the PC
Packet Tracer provides simulated services on devices. You will open a simulated web browser on the PC and request a web page from the server. Click on the PC in the logical workplace. Click the Desktop tab and click the Web Browser button. A simulated web browser opens. Type www.example.com into the URL box and click the Go button to the right. Minimize the simulated browser window. Step 4 – Run the simulation
In the Play Controls section of the Simulation Panel, click the Auto Capture / Play button. The exchange between the PC and the server is animated and the events are added to the Event List. These events represent the PCs request to resolve the URL to an IP address, the server providing the IP address, the PC's request for web page, the server sending the web page in two segments, and the PC acknowledging the web page. A dialog box appears indicating there are no more events and providing information on the timing of the simulation. Click OK to close it.
Task 2: Examine the results Step 1 - Access a specific PDU
Restore the simulated browser window. Notice there is a web page displayed. Minimize the simulated browser window. In the Simulation Panel Event List section, the last column contains a colored box that provides access to detailed information about an event. Click the colored box in the last column for the first event. The PDU Information window opens. Step 2 - Examine the contents of the PDU Information Window
The first tab in the PDU Information window contains information about the inbound and outbound PDU as it relates to the OSI model. Click the Next Layer >> button repeatedly to cycle through the inbound and outbound layers and read the description in the box below the layers to get an overview of how the exchange works. Examine the PDU information for the other events to get an overview of the entire exchange process.
Experiment No-03: Topology Orientation and Building a Small Network Objectives: Upon completion of this lab, you will be able to: • Correctly identify cables for use in the network. • Physically cable a peer -to-peer and switched network. • Verify basic connectivity on each network.
Task 1: Create a Peer-to-Peer Network: Step 1: Connect two workstations. Using the correct Ethernet cable, connect two workstations together. Connect one end of the cable to the NIC port on PC1 and the other end of the cable to PC2. Step 2: Use the following chart to apply a Layer 3 address to the workstations. PC Name
IP Address
Subnet Mask
PC1
192.168.1.2
255.255.255.0
PC2
192.168.1.3
255.255.255.0
Task 2: Verify connectivity. Step 1: Use the ping command to verify that PC1 can reach PC2 and PC2 can reach PC1. From the PC1 command prompt, type ping 192.168.1.3.
Experiment No-04: UDP and TCP Port Numbers Introduction: UDP and TCP are TCP/IP Protocols that correspond to OSI Layer 4, the Transport layer. The PDUs for UDP and TCP differ substantially, but they share the notion of port numbers. Segments contain port numbers that identify the service the client is requesting from the server and port numbers generated by the client to which the server should reply. In addition to port numbers, the TCP segment also contains sequence numbers. Sequence numbers provide reliability by identifying missing segments and allowing the reassembly of the application data by putting the segments back together in the proper order.
Objectives: 1. Setup and run the simulation • Enter simulation mode • Set Event List Filters • Request a web page from the PC • Run the simulation 2. Examine the results • Access specific PDUs • Examine the contents of the PDU Information Window
Task 1: Setup and run the simulation Step 1 – Enter simulation mode
Click the Simulation tab to enter simulation mode. Step 2 – Set Event List Filters
We want to capture only DNS and HTTP events. In the Event List Filters section, click the Edit Filters button and make sure only DNS and HTTP events are selected.
Step 3 – From the PC, request a web page from the Server
Click on the PC in the logical workplace. Open the Web Browser on the Desktop. Type udptcpexample.com into the URL box and click the Go button. Minimize the simulated browser window. Step 4 – Run the simulation
Click the Auto Capture / Play button. The exchange between the PC and the server is animated and the events are added to the Event List. These events represent the client PC's request for DNS service, followed by the request for a web page. The server sends the web page in two segments, and the PC acknowledges the web page. A dialog box appears indicating there are no more events to be captured. Click OK to close it.
Task 2: Examine the results Step 1 - Access specific PDUs
In the Simulation Panel Event List section, the last column contains a colored box that provides access to detailed information about an event. Click the colored box in the last column for the first event. The PDU Information window opens. Step 2 - Examine the contents of the PDU Information Window
In this activity, we will focus only on event information only at Layers 4 and 7. The first tab in the PDU Information window contains information about the inbound and outbound PDU as it relates to the OSI model. Click the Layer 4: and Layer 7: boxes for both the inbound and outbound layers and read the content of the box and description in the box below the layers. Note that DNS uses UDP and HTTP uses TCP. Pay attention to the port numbers. Port 53 represents DNS, the application protocol that associates domain names with IP addresses. Port 80 represents HTTP the application protocol that supports web pages. The other port is generated by the client PC from the range of port numbers greater than 1023. Click the Outbound PDU Details tab. In the TCP segment, note the initial sequence number. Examine the PDU information for the other events in the same fashion. Note the change to the source and destination port numbers (for both UDP and TCP) and the change in the sequence number (for TCP only) as the next segment is delivered. Note that if you use the Reset Simulation button, you must also return to the browser window and press Enter again to re-issue the web page request. This will allow you to re-capture and animate the DNS and HTTP-generated packets.
Experiment No-05 Observing TCP Session Establishment and TCP Session Termination Introduction: TCP is a connection-oriented protocol. Before information, such as a web page, can be exchanged, the peers must establish a connection. A connection is established by a three-way handshake where the initial sequence numbers for both peers are sent and acknowledged. When the exchange is complete, the peers exchange TCP segments to terminate the session properly. The previous activity focused on the actual exchange of TCP segments. This activity will focus on connection establishment before the exchange and session termination following the exchange.
Objectives: 1. Setup and run the simulation • Enter simulation mode • Set Event List Filters • Request a web page from the PC • Run the simulation 2. Examine the results • Access specific PDUs • Examine the contents of the PDU Information Window
Task 1: Setup and run the simulation Step 1 – Enter simulation mode
To verify the connection, click on the PC in the logical workplace. Open the Web Browser on the Desktop. Type192.168.1.2 into the URL box and click the Go button. The web page should appear. Click the Simulation tab to enter simulation mode. Step 2 – Set Event List Filters
We want to capture only TCP events. In the Event List Filterssection, click the Edit Filters button. Select only TCP events. TCP events include TCP based application protocols like HTTP and Telnet.
Step 3 – Request a web page from the PC
Restore the web browser window. In the Web Browser , click the Go button to request that the web page be resent. Minimize the simulated browser window. Step 4 – Run the simulation
Click the Auto Capture / Play button. The exchange between the PC and the server is animated and the events are added to the Event List. These events represent the establishment of the TCP session, the PC's request for web page, the server sending the web page in two segments, the PC acknowledging the web page, and the termination of the TCP session. A dialog box appears indicating there are no more events. Click OK to close it.
Task 2: Examine the results Step 1 - Access specific PDUs
In the Simulation Panel Event List section, the last column contains a colored box that provides access to detailed information about an event. Click the colored box in the last column for the first event. The PDU Information window opens. Step 2 - Examine the contents of the PDU Information Window
In this activity, we will focus only on event information only at Layer 4. The first tab in the PDU Information window contains information about the inbound and outbound PDU as it relates to the OSI model. Click the Layer 4: boxes for both the inbound and outbound layers and read the content of the box and description in the box below the layers. Pay attention to the type of TCP segment. Click the Outbound PDU Details tab. In the TCP segment, note the initial sequence number. Examine the PDU information for the first four TCP events in the same fashion. These events show the three-way handshake that establishes the session. Note the type of TCP segment and the change in the sequence number. Examine the PDU information for the TCP events that follow the main HTTP exchange in the same fashion. These events show the session termination. Note the type of TCP segment and the change in the sequence number. Note that if you use the Reset Simulation button in the Event List window, you will need to return to the web browser URL line and press enter to re-initiate the process.
Experiment No-6 Router Packet Forwarding Introduction: IP packets are forwarded between networks by routers that check their IP routing tables to find the next hop to the destination network. If there is an entry for the destination network in the routing table, the router will forward the packet out the interface indicated in the routing table. If there is no entry for the destination network in the routing table but there is a default route, the router will forward the packet out the interface indicated in the routing table for the default route. If there is no entry for the destination network in the routing table and there is no default route, the router will drop the packet. This activity will use a configuration containing three routers, connecting three LANs. The first LAN is 10.1.1.0/24 that contains PC_A. The second LAN is 10.1.2.0/24 that contains PC_B. The last LAN 10.1.3.0/24 that contains PC_C. Router0 has a route to 10.1.2.0/24 and Router2 has a route to 10.1.1.0/24. So a ping from PC_A will reach PC_B and the reply will reach PC_A. Router0 has no route to 10.1.3.0/24 but has a default route out interface S0/0/1 (toward Router1). Router1 has no route to 10.1.1.0/24 and no default route. So a ping from PC_A will reach PC_C but the reply will be dropped by Router1.
Objectives: 1. Examine how routers forward packets in three cases: • When a route to the destination exists in the routing table • When no specific route exists, but a default route has been configured • When neither a specific route nor a default route exists
Task 1: Run the Simulation using Scenario 0, from PC_A to PC_B. Step 1 – Enter Simulation mode and send the packet. The file loads with Scenario 0, which has a predefined packet from PC_A to PC_B, listed in the User Created PDU window at the lower right. Double click on the Fire button once in Realtime mode that will populate the ARP tables and make interpreting the routing behavior more clear. Click the Simulation tab to enter Simulation mode. The test packet will appear in both the Event List and on the logical topology. Use the Inspect Tool(the magnifying glass on the far right) to open up the routing tables for Router0, Router1, and Router2. Inspect the packet by clicking on the colored square in the Info column of the Event List.
Step 2 – Trace the packet. Use the Capture / Forward button to move the packet through the network. Inspect the packet at each step, particularly at the routers. Compare the OSI Model tab explanations of the packet's processing with the displayed routing table. Note that both the ICMP echo request from PC_A to PC_B and the ICMP echo reply from PC_B back to PC_A can complete their journey because of the specific entries in the routing table.
Task 2: Run the simulation using Scenario 1, from PC_A to PC_C. Step 1 - Move to Scenario 1 Once you are done with Scenario 0, change to Scenario 1. You will still be in Simulation mode, so switch to Realtime mode long enough to allow the ping from PC_A to PC_C to show "Failed" in the Last Status column. This will populate the ARP tables and simplify the interpretation of the routing behavior. Switch back to Simulation mode. Inspect the packet by clicking on the colored square in the Info column of the Event List.
Step 2 - Trace the packet. Use the Capture / Forward button to move the packet through the network UNTIL it gets to PC_C (then pause). Inspect the packet at each step until PC_C, particularly at Router0 and Router1. Compare the OSI Model tab explanations of the packet's processing with the displayed routing tables. Note that the ICMP echo request from PC_A to PC_C can complete its journey because a default static route exists on Router0 and the destination network is directly connected to Router1. However, these routes do not "point" in both directions.
Task 3: Continue running the simulation Using Scenario 1, From PC_C to PC_A. Step 1 - Trace the packet. Use the Capture / Forward button to move the packet through the network. Inspect the packet at each step, in particular at Router1. Compare the OSI Model Tab explanations of the packet's processing with the routing table of Router1, and note what happens to the ICMP echo reply packet from PC_C to PC_A.
Experiment No-07 Observing Dynamic Routing Protocol Updates Introduction: Routers can learn about routes from other routers by using dynamic routing protocols. In such protocols, which may run according to timers or triggering events or both, routers have been configured to exchange information. RIP version 1 is a simple dynamic routing protocol that has been configured on Routers A, B, and C.
Objectives: 1. Examine the behavior of a dynamic routing protocol, RIP v1 • Visualize the process of dynamic routing. • Examine the routing update packets.
Task 1: Run the simulation. Step 1 – Enter Simulation mode Click the Simulation tab to enter Simulation mode. Also, use the Inspect Tool (magnifying glass) to display the routing tables for each router.
Step 2 - Step through the simulation. Click the Capture / Forward button; the routers will send update packets. There are several special features of how these routers have been configured. Note that Router A is not sending any update packets, Router B is sending updates to both Router A and Router C, and Router C has been configured not to send routing updates to the LANs to which it is connected. If you encounter a "No More Events" message, just click the OK button and continue clicking the Capture / Forward button. Note also that even though no user data traffic (no web page requests, no pings) is being sent across the network, the network is still "alive" with communications so that the routers have an up-to-date picture of the how to forward packets to their destination.
Task 2: Examine the routing update packets As you are clicking the Capture / Forward button, routing update packets are observed. By clicking on either the packet envelope, or the colored square in the Info column of theEvent List, examine these routing update packets by opening the PDU information window. Use both the OSI Model tab view and the Inbound/Oubound PDU Details tabs views to explore the routing updates. You will learn much more about routing protocols and how to configure routers in future courses.
Experiment No-08 Simple Wireless LAN Model Introduction: Wireless LANs are an increasingly important technology. They will be covered in more depth in later courses. What is presented here is a simple model of a wireless LAN setup that might be found in a home or small business.
Objectives: 1. Examine the Wireless LAN network. • Open the various devices and examine their configurations. • Verify connectivity in Realtime mode by opening a web page. 2. Run the simulation. • Start the simulation. • Examine a ping packet at each step from the Home PC to the web se rver and back.
Task 1: Examine the Wireless network. Step 1 – Open the various devices and examine their configurations.
Examine the devices that make up the wireless network using both the Physical and the Config tabs. Note especially the following:
Both the PC and the printer have a Linksys wireless adapter installed. Also click the PC Wireless button on the PC's Desktop tab. On the wireless router, also examine the contents of the GUI tab. The "Model of ISP" device is a Packet Tracer cluster. Click on it to open it and display the devices that it contains. When finished examining the devices, click the Root=> button on the yellow bar in the upper left to close it.
Step 2 – Verify connectivity in Realtime mode by opening a web page. While in Realtime mode, open the Web Browser from the Desktop of the Home PC. Type myispweb.com into the URL and press the Enter key. The web page should be retrieved. This process helps populate tables so you can focus on just the ICMP packets.
Task 2: Run the simulation. Step 1 – Start the simulation. Switch to Simulation mode. We want to capture only ICMP events. In the Event List Filters section, verify that only ICMP events are selected. The packet at the Home PC is a single ICMP echo request that will be sent to the ISP's web server through the wireless network.
Step 2 – Examine a ping packet at each step from the Home PC to the web server and back.
Examine the packet at the Home PC. Then click Capture / Forward again and again, opening the packet for examination at each step in the process.
