Network devices are physical hardware components that link computers, printers, fax machines, and other electronic devices to a network. These devices quickly, securely, and accurately transfer data over the same or separate networks. Network equipment can be either intra or inter-networked.
A NIC card or RJ45 connection is an installed device, whereas a router, switch, or another network device is a network component.
A computer may send and receive data through phone or cable lines with the help of a modem. In contrast to a telephone line or cable wire, which can only carry analog data, the data saved on a computer is digital.
The modem’s primary job is to transform digital signals between analog and digital and vice versa. Combining a modulator and a demodulator creates a modem. When digital data is sent by the computer, the modulator turns it into analog data. When analog data signals are received by the computer, they are demodulated into digital data.
Types of Modem
There are several different types of modems depending on the direction of data transmission:
Simplex − Using a simplex modem, data can only be transferred from a digital device to a network (modulator) or from a network to a digital device in one direction (demodulator).
Half duplex − While a half-duplex modem can transport data in both ways, it can do so only in one direction at a time.
Full duplex − A full duplex modem may simultaneously send data in both directions.
Hub:
Hubs work in the physical layer of the OSI model. A hub is a device for connecting multiple Ethernet devices and making them act as a single network segment. It has multiple inputs and output ports in which a signal introduced at the input of any port appears at the output of every port except the original incoming port.
A hub can be used with both digital and analog data. Hubs do not perform packet filtering or addressing function, they send the data packets to all the connected devices.
Demonstrate the functionality of a hub using Cisco Packet Tracer (CPT)
1. Open Cisco Packet Tracer
Launch Cisco Packet Tracer on your computer.
2. Create a New Project
Go to File > New to start a new project.
3. Add Devices to Your Workspace
From the bottom device toolbar, choose the following devices:
Hub: You can find this under the Network Devices tab > Hubs.
PCs: Select End Devices > PC.
Drag and drop one Hub and at least two PCs onto the workspace.
4. Connect the Devices
Choose the Connections icon (it looks like a lightning bolt).
Select the Copper Straight-Through cable.
5. Click on the first PC, choose the FastEthernet0 interface.
Connect it to one of the ports on the Hub.
Repeat this process for the second PC, connecting it to a different port on the Hub.
6. Configure IP Addresses for the PCs
Click on the first PC and then on the Desktop tab.
Select IP Configuration.
Assign an IP address and subnet mask (e.g., IP: 192.168.1.1, Subnet Mask: 255.255.255.0).
Repeat this for the second PC, assigning a different IP address but the same subnet mask (e.g., IP: 192.168.1.2, Subnet Mask: 255.255.255.0).
7. Verify Connectivity
On the first PC, go to Command Prompt under the Desktop tab.
Type ping 192.168.1.2 and press Enter.
You should see replies from the second PC if everything is set up correctly.
8. Observe the Hub’s Operation
To observe how the hub works, click on the Hub.
Go to the Physical tab and then select Power to turn it on.
Note that a hub is a Layer 1 device and doesn’t have advanced configuration options. It simply forwards packets to all connected devices.
9. Use Simulation Mode for Detailed Analysis
Switch to Simulation Mode by clicking the Simulation tab.
Set up a simple Ping simulation by adding an Event to the network.
Observe how the hub broadcasts the frame to all ports and how only the intended recipient responds.
10. Verify Frames Being Broadcast
In Simulation Mode, add the PCs and use the Add Simple PDU tool to send a message from one PC to another.
Watch how the hub sends the frame out of all ports, but only the destination PC will respond.
11. Save Your Project
Go to File > Save and choose a location to save your Packet Tracer file for future reference.
Repeater:
A repeater operates at the physical layer of the OSI model.A Repeater connects two segments of a network cable.Sometimes it regenerates the signals to proper amplitudes and sends them to the other segment.If the signal becomes weak, it can copy the signal bit by bit and regenerate it at the original strength.It is a 2-port device.
Demonstrate the functionality of a Repeater using Cisco Packet Tracer (CPT):
A repeater is used to extend the range of a network by amplifying signals, so this exercise will help you understand how a repeater works to maintain connectivity over greater distances.
1. Open Cisco Packet Tracer
Launch Cisco Packet Tracer on your computer.
2. Create a New Project
Go to File > New to start a new project.
3. Add Devices to Your Workspace
From the bottom device toolbar, choose the following devices:
Repeater: You can find this under the Network Devices tab > Hubs.
PCs: Select End Devices > PC.
Drag and drop one Repeater and at least two PCs onto the workspace.
4. Connect the Devices
Choose the Connections icon (it looks like a lightning bolt).
Select the Copper Straight-Through cable.
Connect one PC to the first port of the Repeater.
Connect the Repeater’s second port to another PC.
Note: Ensure the distance between the PCs is sufficient to show the benefit of the repeater. You may want to place the repeater in between to visually represent its function.
5. Configure IP Addresses for the PCs
Click on the first PC and then on the Desktop tab.
Select IP Configuration.
Assign an IP address and subnet mask (e.g., IP: 192.168.1.1, Subnet Mask: 255.255.255.0).
Repeat this for the second PC, assigning a different IP address but the same subnet mask (e.g., IP: 192.168.1.2, Subnet Mask: 255.255.255.0).
6. Verify Connectivity
On the first PC, go to Command Prompt under the Desktop tab.
Type ping 192.168.1.2 and press Enter.
You should see replies from the second PC if everything is set up correctly.
7. Observe the Repeater’s Operation
To observe the repeater's operation, you can use the Physical tab to view the repeater's connections and ensure it’s powered on.
The repeater doesn’t have advanced settings; it simply forwards electrical signals to extend the network range.
8. Use Simulation Mode for Detailed Analysis
Switch to Simulation Mode by clicking the Simulation tab.
Set up a simple Ping simulation by adding an Event to the network.
Observe how the signal from one PC travels through the repeater to the other PC.
9. Verify Signal Transmission
In Simulation Mode, add the PCs and use the Add Simple PDU tool to send a message from one PC to another.
Watch how the repeater amplifies the signal to ensure it reaches the other PC.
10. Save Your Project
Go to File > Save and choose a location to save your Packet Tracer file for future reference.
Switch
Switches may operate at one or more layers of the OSI model. They may operate in the data link layer and network layer; a device that operates simultaneously at more than one of these layers is known as a multilayer switch.
A Switch can check the errors before forwarding the data, which makes it more efficient and improves its performance. A switch is the better version of a hub. It is a multi-port bridge device.
Demonstrate the functionality of a switch using Cisco Packet Tracer (CPT): Fundamental role of a switch in forwarding traffic efficiently within a network. Here’s a step-by-step guide to illustrate the operation of a switch:
1. Open Cisco Packet Tracer
Launch Cisco Packet Tracer on your computer.
2. Create a New Project
Go to File > New to start a new project.
3. Add Devices to Your Workspace
From the bottom device toolbar, choose the following devices:
Switch: You can find this under the Network Devices tab > Switches.
PCs: Select End Devices > PC.
Drag and drop one Switch and at least two PCs onto the workspace.
4. Connect the Devices
Choose the Connections icon (it looks like a lightning bolt).
Select the Copper Straight-Through cable.
Connect one PC to one of the ports on the Switch.
Connect the second PC to another port on the Switch.
Repeat this process if you want to add more PCs to the Switch.
5. Configure IP Addresses for the PCs
Click on the first PC and then on the Desktop tab.
Select IP Configuration.
Assign an IP address and subnet mask (e.g., IP: 192.168.1.1, Subnet Mask: 255.255.255.0).
Repeat this for the second PC, assigning a different IP address but within the same subnet (e.g., IP: 192.168.1.2, Subnet Mask: 255.255.255.0).
6. Verify Connectivity
On the first PC, go to Command Prompt under the Desktop tab.
Type ping 192.168.1.2 and press Enter.
You should see replies from the second PC if everything is set up correctly.
7. Observe the Switch’s Operation
To observe the switch’s operation, click on the Switch.
Go to the CLI tab to access the command-line interface.
Use basic commands like show mac address-table to view the MAC address table of the switch.
Example CLI Commands:
show mac address-table: Displays the MAC address table, showing which MAC addresses are associated with which switch ports.
commands to show MAC address using CLI
Switch>enable
Switch#show mac-address-table
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
1 0000.0cc0.6a7d DYNAMIC Fa0/2
1 0002.4ab0.2786 DYNAMIC Fa0/1
1 0004.9ab0.85da DYNAMIC Fa0/3
8. Use Simulation Mode for Detailed Analysis
Switch to Simulation Mode by clicking the Simulation tab.
Add a simple Ping simulation by using the Add Simple PDU tool to send a message from one PC to another.
Observe how the switch learns the MAC addresses and forwards the frame only to the port where the destination PC is connected.
9. Verify Frame Forwarding
In Simulation Mode, observe how the switch uses its MAC address table to forward the frame from one PC to another.
Note that the switch only sends the frame to the port associated with the destination MAC address, unlike a hub, which would broadcast the frame to all ports.
10. Save Your Project
Go to File > Save and choose a location to save your Packet Tracer file for future reference.
Bridge
A bridge operates at the data link layer of the OSI model. It can read only the outmost hardware address of the packet but cannot read the IP address. It reads the outmost section of the data packet to tell where the message is going. It reduces the traffic on other network segments. It does not send all the packets. So, a bridge can be programmed to reject packets from a particular network.
Note:
1. Bridge is a layer 2 device which is used to connect the same protocols used for 2 different LANS
2. Router is a layer 3 device which is used to connect the Different protocols used for 2 different LANS
Steps to Observe MAC Address Functionality:
Setup a Simple Network:
Create a basic network topology with devices such as PCs, switches (bridges), and routers.
For example, connect two PCs (PC1 and PC2) to a switch.
Configure IP Addresses:
Assign IP addresses to the PCs to ensure they can communicate with each other.
E.g., assign 192.168.1.1/24 to PC1 and 192.168.1.2/24 to PC2.
Access the Switch (Bridge):
Click on the switch in the Packet Tracer workspace to open the switch's configuration menu.
Access the CLI (Command Line Interface) of the switch.
Send Traffic Between PCs:
Use one of the PCs (e.g., PC1) to send a ping to the other PC (e.g., PC2).
This will generate traffic that the switch needs to forward, prompting it to learn the MAC addresses.
View the MAC Address Table:
On the switch's CLI, enter the command show mac address-table or show mac-address-table.
This command will display the MAC addresses that the switch has learned and the corresponding ports.
Switch> enable
Switch# show mac-address-table
Analyze the MAC Address Table:
The MAC address table will show you the MAC addresses of the devices connected to the switch and the port numbers they are associated with.
Each entry in the MAC address table indicates that the switch has learned the MAC address of a device on a specific port.
Router
Routers are small physical devices that operate at the network layer to join multiple networks together.A router is a device like a switch that routes data packets based on their IP addresses.
Routers normally connect LANs and WANs and have a dynamically updating routing table based on which they make decisions on routing the data packets.
A Router divides the broadcast domains of hosts connected through it.
Routers perform the traffic directing functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination code.
Routers may also be used to connect two or more logical groups of computer devices known as subnets, each with a different subnetwork address. The subnet addresses recorded in a router do not necessarily map directly to the physical interface connections.
Demonstrate the functionality of a Router using Cisco Packet Tracer (CPT):
1: Setup the Network Topology
Open Cisco Packet Tracer.
Add Devices to the Workspace:
Drag and drop the following devices onto the workspace:
1 Router (e.g., Router0)
2 Switches (e.g., Switch0, Switch1)
4 PCs (e.g., PC0, PC1, PC2, PC3)
Connect Devices:
Use the Copper Straight-Through cable to connect:
PC0 to Switch0
PC1 to Switch0
PC2 to Switch1
PC3 to Switch1
Use the Copper Straight-Through cable to connect:
Switch0 to Router0 on the GigabitEthernet 0/0 interface
Switch1 to Router0 on the GigabitEthernet 0/1 interface
2: Configure IP Addresses on PCs
Configure PC0 and PC1 (Subnet 1):
Click on PC0, go to the Desktop tab, and select IP Configuration.
Assign the following IP details:
IP Address: 192.168.1.2
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.1
Repeat the same for PC1, but with an IP Address of 192.168.1.3.
Configure PC2 and PC3 (Subnet 2):
Click on PC2, go to the Desktop tab, and select IP Configuration.
Assign the following IP details:
IP Address: 192.168.2.2
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.2.1
Repeat the same for PC3, but with an IP Address of 192.168.2.3.
3: Configure IP Addresses on Router Interfaces
Access Router CLI:
Click on the Router0 and go to the CLI tab.
Configure Router Interfaces:
Enter the following commands to configure the IP addresses for the router’s interfaces:
shell
Copy code
Router> enable
Router# configure terminal
Router(config)# interface gigabitEthernet 0/0
Router(config-if)# ip address 192.168.1.1 255.255.255.0
Router(config-if)# no shutdown
Router(config-if)# exit
Router(config)# interface gigabitEthernet 0/1
Router(config-if)# ip address 192.168.2.1 255.255.255.0
Router(config-if)# no shutdown
Router(config-if)# exit
Router(config)# end
Router# write memory
This sets up the router to be in the same subnet as the PCs on their respective networks.
4: Test Connectivity Between PCs
Ping within the Same Subnet:
Go to PC0, open the Command Prompt, and type the following command:
shell
Copy code
ping 192.168.1.3
This tests connectivity between PC0 and PC1 on the same subnet.
Ping Across Different Subnets:
From PC0, ping PC2 using the command:
shell
Copy code
ping 192.168.2.2
If successful, this shows that the router is correctly routing packets between different subnets.
Two types of routers −
Static routers – Static routers are configured manually and route data packets based on the information in a router table.
Dynamic routers – Dynamic routers use adaptive routing which is a process where a router can forward data by a different route
Gateway
A gateway is an internetworking capable of joining together two networks that use different base protocols.
A network gateway can be implemented completely in software, hardware, or a combination of both, depending on the types of protocols they support.
A network gateway can operate at any level of the OSI model. A broadband router typically serves as the network gateway, although ordinary computers can also be configured to perform equivalent functions.
A gateway is a router or proxy server that routes between networks.
A gateway belongs to the same subnet to which the PC belongs.
Steps to Configure and Use a Gateway in Cisco Packet Tracer
Create a Basic Network Topology:
Place at least one PC, one switch, and one router on the workspace.
Connect the PC to the switch using a copper straight-through cable.
Connect the switch to the router using another copper straight-through cable.
Assign IP Addresses:
Assign an IP address to the PC.
Click on the PC, go to the Desktop tab, and select IP Configuration.
Assign an IP address (e.g., 192.168.1.2) and a subnet mask (e.g., 255.255.255.0).
Set the default gateway to the router's IP address on the same network (e.g., 192.168.1.1).
Configure the router's interface:
Click on the router, go to the CLI or Config tab.
Select the interface connected to the switch (e.g., GigabitEthernet0/0).
Assign an IP address (e.g., 192.168.1.1) and subnet mask (255.255.255.0) to the router's interface.
Enable the interface with the no shutdown command if using the CLI.
Example configuration for the router:
Router> enable
Router# configure terminal
Router(config)# interface GigabitEthernet0/0
Router(config-if)# ip address 192.168.1.1 255.255.255.0
Router(config-if)# no shutdown
Configure the PC's Default Gateway:
The PC's default gateway should be the IP address of the router's interface connected to the switch (e.g., 192.168.1.1).
This tells the PC where to send packets destined for outside the local network.
Test Connectivity:
You can test connectivity by pinging the router's IP address from the PC.
Open the command prompt on the PC (Desktop > Command Prompt) and type:
ping 192.168.1.1
If everything is configured correctly, you should receive replies, indicating that the PC can communicate with the router (gateway).
Routing Beyond the Gateway (Optional):
If your router is connected to another network (e.g., a simulated internet), you can configure routing on the router to forward traffic to that network.
For example, you can set up a static route or use a dynamic routing protocol to enable communication between different networks.
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