Prerequisite – How ARP works?
To transfer a packet from source to destination, both MAC address and IP address of the destination should be known. If the destination MAC address is not present then ARP will resolve this issue first then the packet will be delivered to destination host.
To transfer a packet from source to destination, both MAC address and IP address of the destination should be known. If the destination MAC address is not present then ARP will resolve this issue first then the packet will be delivered to destination host.
There are simple rules for a packet flow in a network:
- If the destination host is present in the same network of the source host then the packet will be delivered directly to the destination host using MAC address.
- Within a network, the packet will be delivered on the basis of MAC address.
- MAC address never crosses its broadcast domain.
Now, first we have to take an idea about ARP.
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Address Resolution Protocol –
Address Resolution Protocol is a layer 2(Data link layer) protocol which is used to find MAC address of the known IP address.
Address Resolution Protocol is a layer 2(Data link layer) protocol which is used to find MAC address of the known IP address.
There are some important terms associated with ARP:
ARP cache is a table maintained by ARP which contains IP address with its associated MAC address and type. If MAC address is learned dynamically then the type will be dynamic and if MAC address is added manually then type will be static.
ARP request is a broadcast message generated by the source to find the destination MAC address if the ARP is not resolved initially.
ARP reply is a unicast message from destination to source device containing the destination MAC address.
Explanation –
The steps included in ARP process are as follows :-
When a source wants to send a packet to destination device then,
- The source ARP cache is check if the ARP is resolved or not. If the ARP is not resolved, it puts the packet on hold and generates an ARP request.If the ARP is already resolved then the packet will be delivered to destination host.
- The ARP request is broadcast all over the network to find out the device having destination IP address.
Note – If the destination is present in the same network then ARP will find out destination MAC address but if it is present in different network then ARP will find out default gateway MAC address. - When the device having the destination IP address receives the ARP request, it updates it’s own ARP cache.
- The destination host machine generates an ARP reply containing it’s own MAC address.
- Now,the device having the source IP address receives the ARP reply and update it’s ARP cache.
- Since,both source and destination IP address and MAC address are available now therefore the packet is delivered to the destination host.
Now, we have taken an idea about the ARP protocol. Let’s see about the packet flow.
Now we will understand how the packet is delivered to destination when the destination is present in same network(network of the source).
Here is the topology in which host A having IP address 192.168.1.1, host B having IP address 192.168.1.2 and the router having IP address 192.168.1.3 on interface fa0/0.
Now how source device will know that the destination is present in same or different network. Let us understand :-
AND operation is performed between source IP address, source subnet mask and destination IP address, source subnet mask. If the resultant of both is same then the destination is present in the same network otherwise in different network.
Let us try to ping host B from host A.
As you can see 2 packets are generated, one of ICMP and the other of ARP(green). ARP frame is generated because the host A has not yet communicated to host B i.e. the ARP has not been resolved i.e ARP will be resolved first so that host A have an entry for host B MAC address.
As already explained the ARP request will be broadcast first for the target IP address within the network because routers do not forward broadcast packet.The broadcast request is recieved by the switch as shown in the above figure.
The switch broadcast the ARP request as the entry in the ethernet header is FFFF.FFFF.FFFF (broadcast MAC address).
The request is recieved by host B as shown in the above figure.The host B generates an ARP reply immediately specifying its own MAC address.
Now the host B unicast the ARP reply to the host A which is recieved by the switch which in turn forward it to the host A as shown in the above 2 figures.
Note –
The switch is able to unicast the reply because the switch has put an entry for host A in it MAC table when the host A broadcast the ARP request.in the same way,switch has also put an entry for the host B when the switch recieves the ARP reply.
The switch is able to unicast the reply because the switch has put an entry for host A in it MAC table when the host A broadcast the ARP request.in the same way,switch has also put an entry for the host B when the switch recieves the ARP reply.
Now the ARP has been resolved and the ICMP will be unicast to the host B from host A(as shown above).
Now the ICMP akcnowledgement packet will be unicast from host B to host A i.e. host B is successfully ping from host A as shown in the above figures.
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How to Use Cisco Packet Tracer Step by Step? – Cisco Packet Tracer allows us to simulate network applications virtually on our PC. This program is mostly used by people working Cisco exams. It also uses people who want to improve themselves in the field of networking.
How to Use Cisco Packet Tracer Step by Step?
How to Use Cisco Packet Tracer Step by Step?
In the previous article, we explained what is Cisco Packet Tracer Software before using Cisco Packet Tracer step by step. In this article, we will examine the basic Cisco Packet Tracer usage and configuration.
If you haven’t installed the Cisco Packet Tracer program on your computer, you can read how to install Cisco Packet Tracer 7 on Windows 10.
Once you have installed the Cisco Packet Tracer program on your computer, you can now design your network. But basically, it is essential to understand the good use of the program. So let’s do the Cisco Packet Tracer usage and configuration.
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Download Cisco Packet Tracer Software
Before you configure and use Cisco Packet Tracer step by step, you can download and install the appropriate version of Windows from the program.
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Cisco Packet Tracer Basic Configuration
By using Cisco Packet Tracer step by step, you can easily create a network topology. The usage and configuration of Cisco Packet Tracer include the desktop computer, laptop, server etc. You can add devices and create connections between them.
In order to use Cisco Packet Tracer step by step, follow the steps below.
Adding Computers in Cisco Packet Tracer
To add a computer in Cisco Packet Tracer, click on the [End Devices – Recent Devices] section as shown in the image below.
Drag and drop a desktop computer to the workspace.
As in real life, we can also turn on and off virtual machines in the use of Cisco Packet Tracer. Yellow light in the image below means that the computer is working.
Assign IP Address to Computer in Cisco Packet Tracer
In the process to use Cisco Packet Tracer, let’s take a look at that where do the Ip settings make from. Like a real computer, we can give IP addresses to the computers we add in this program.
Click on the Desktop tab in PC0’s properties, as shown in the following image. Then click on Ip Configuration.
After configuring the IP address setting of the computer, you need to assign the static Ip address to the computer if there is not DHCP Server in the network.
Enter PC0 IP address settings as follows.
Click (X) to check the PC0 IP address configuration from the CMD prompt. If you exit from the tab windows by pressing (X), the settings will save automatically.
From the PC0 properties, click on Command Prompt.
As in our actual computer, when we checked the PC0 Ip configuration with the ipconfig command, we successfully performed the Cisco Packet Tracer computer configuration step.
Adding a Switch to a Cisco Packet Tracer
Adding a Switch in Cisco Packet Tracer is also very simple. To add a Switch to the workspace, click on the section of Cisco Packet Tracer devices (Network Devices), then you can add it from Switches under the options under Network Devices.
Click on the network devices as shown below.
Under Network devices, click Switches.
We can from here add the Switch in Cisco Packet Tracer. Drag and drop the Switch to the work area, as shown in the following image.
Once you have added the switch to the workspace, click once to open the Switch0 properties.
The physical appearance of the switch in the Switch0 specification is as shown in the following image.
In the Switch0 features include Switch interfaces in the Config section.
Switch0 CLI tab is used to configure the Cisco Switch with commands.
Connecting Network Devices in Cisco Packet Tracer
We completed the process of adding a switch to the Cisco Packet Tracer. Now, we will connect the network devices on the Cisco Packet Tracer. To do this, click the wiring option as shown in the following image.
Then, click once on PC0.
Select the FastEthernet0 network card on PC0.
Do the same process on Switch0 and connect it to the FastEthernet0/1 interface.
As shown in the image below, the connection between the computer and the switch are established. We can understand that the devices linked up with each other thanks to green icon.
Let’s add one laptop to use the laptop on Cisco Packet Tracer.
This is how the network devices connect in Cisco Packet Tracer. Do the same process on the Laptop you added to the workspace as well.
Open the Laptop0 properties, click the Ip configuration option on the Desktop tab, and set the Laptop0’s IP address.
Using Ping in Cisco Packet Tracer
Pinging on the Cisco Packet Tracer is done by entering the command from the properties of the network device. To ping PC0 from Laptop0, execute the command ping 192.168.10.10 by opening a command prompt.
Pinging from Laptop0 to PC0 is successful.
When we ping from PC0 to Laptop0, you can see that the ping process is successful. As a result, the connection between the desktop computer and the Laptop computer provide.
In the process yo configure to use Cisco Packet Tracer, also, there is the PDU packet of the realtime according to the ping command. To use the PDU packet, click the PDU option in the right section as you see in the image below.
To expand this option, press the left arrow as shown below.
Then, click the Add Simple PDU option in the right pane.
After you click on ADD Simple PDU to ping from the program, you will see an envelope-like image. Click on the devices you want to ping as a source and destination.
By clicking once on PC0 and then clicking on Laptop0, we can perform the ping operation by specifying the source and target devices.
Immediately after you leave the envelope on Laptop 0, you will see a message on the Realtime tab that the ping is successful. The successful message means success. You can also see that it is used the ICMPprotocol in the Realtime section.
Configuring Wireless Router in Cisco Packet Tracer
On the Cisco Packet Tracer, before you configure the wireless modem, click the WRT300N wireless modem in the workspace by following the wireless devices option from the network devices.
When the wireless modem is active, you can drop it at the location you want to add to the workspace.
Once added the WRT300N to the workspace, click once on it.
To connect the wireless modem to Switch0, first, click on the cable from the bottom and connect to the GigabitEthernet0/1 interface.
Then select the Ethernet1 port by clicking on the wireless modem.
Once you have completed wiring between the wireless modem and Switch0, click on the GUI tab of the wireless modem properties.
To set the wireless modem LAN settings, enter the wireless LAN local network IP address in the Network Setup option. We had made the default gateway IP address 192.168.10.1 the Ip configuration in other the network devices. For the Modem interface Ip address, enter 192.168.10.1 Ip address.
Then, leave the DHCP setting active.
The point to be noted here is that you do not press (X) immediately. You can’t automatically save the settings on the wireless modem. So, you have to go down a bit and save the settings.
Save the settings by pressing the Save Settings button.
If we ping from PC0 to the Wireless Router, we can see that the connection established successfully.
In the processes to configure and use Cisco Packet Tracer, I add one smartphone to the program’s workspace. To add a smartphone in the Cisco Packet Tracer, click on the last devices and click on the Smart Device Phone in the right part.
Once you’ve selected your smartphone, click where you want to add it.
Our smartphone is added to the workspace and connected to the wireless modem. For this reason, we should leave the DHCP setting on the wireless modem enabled.
Go to the Desktop tab from the smartphone features.
After clicking on the Ip configuration option, we can see that the IP address obtained from the DHCP server of the wireless modem.
Pinging is successful from the SmartPhone to the Wireless Router.
Adding to Workspace Notes in Cisco Packet Tracer
While we use Cisco Packet Tracer program, we add clarifications to design the network topologies properly. Adding clarifications such as IP address, computer name, server service name, Switch name, and Router name to the workspace increases clarity. By this way, you can make a nice and neat network map.
Click on the note (Place Note) on the right side of the program to add descriptions to the Cisco Packet Tracer workspace. Then click on the workspace.
When you click on the workspace, the text box will open. Type in descriptions according to topology into the box.
You can add descriptions to network devices as shown in the following image.
The Use of Shapes in Cisco Packet Tracer
The use of shapes on the Cisco Packet Tracer ensures that the generated topology is much more descriptive than the network topology.
To work with Cisco Packet Tracer shapes, you can select the shape you want to draw from the window that opens by clicking the down arrow next to the red circle on the right side of the program.
Once you click on the red circle, the Palette Dialog window will open. We select the shape we want to draw and then let’s configure it with the Color buttons. There are 2 options here;
1. No Fill
This option will not fill the shape drawn with the color.
2. Fill Color
This option fills the color scheme we choose.
As an example, I colored the circle shape as in the image below.
Now draw the shape on the workspace.
As another example, we can add a colorless rectangle. The Cisco Packet Tracer provides the easier understanding of the work done with the use of shapes. You can see this from the image below.
Resizing Shapes in Cisco Packet Tracer
Once you have created the shapes in the Cisco Packet Tracer, if you want to resize it, we can do it with the Resize Shape feature on the right.
Click Resize Shape.
After clicking on the Resize Shape, a red dot will appear on the edges of the shapes. We can resize the shapes we made with red dots.
After resizing the shapes, press the Select (or Esc) key.
And the created shape is resized.
Deleting a Cisco Packet Tracer Device or Shapes
The process of deleting Cisco Packet Tracer devices and shapes deletion means that all devices or shapes remove from the workspace.
While we use Cisco Packet Tracer, to delete devices or shapes in the workspace, we use the X key as shown in the following image.
Then click on the device or shape you want to delete and click once with the left mouse button.
The rectangular shaped cylinder removed from the workspace. Do the same process for other circle shapes.
Delete the smartphone connected to the wireless mode to remove it from the workspace.
The smartphone has also successfully deleted from the workspace.
How to Cisco Packet Tracer Step by Step? ⇒ Video
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Final Word
How to Use Cisco Packet Tracer Step by Step? – In this article, we have configured the basic network setup of Cisco Packet Tracer. We have studied Packet Tracer usage step by step.
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