OSI model refers to open system interconnection which implements seven layers define in a network framework. The first four (1-4) lower layers majorly deals with data by transmitting from one point to another whereas the last three (5-7) upper layers is where it holds application-level data. Data operates from one layer to the other.
| Layers | Application program |
| Layer 7 | Application Layer |
| Layer 6 | Presentation Layer |
| Layer 5 | Session Layer |
| Layer 4 | Transport Layer |
| Layer 3 | Network Layer |
| Layer 2 | Link Layer |
| Layer 1 | Physical Layer |
| Cabling |
The layers shown above depicts how data is exchanged between the protocols.
Below is a brief description of each layer.
In this protocol file or message are divided into packets. These packets are transmitted over the internet which after that assembly as soon as they arrive in their destination. Addressing the packets on the internet is specifically done by internet protocol. It has the following layers which serve different purposes.
| layer | Application program |
| Layer 4 | Application |
| Layer 3 | Transport |
| Layer 2 | Internet |
| Layer 1 | Datalink |
License agreement need to be agreed upon for the installation process to proceed
Will installing the Wireshark, there is an additional task you can add which is shown above
In the installation, there is an option to include winpcap version as well as you can skip.
From the pop-up, the USBPcap is already installed
After running the Wireshark the above analysis is shown
This is the default installation directory of the Wireshark
These are the components you can include in the Wireshark setup
The above is the WIFI analyzer at which the interconnect network is shown
Wireshark conversations show the amount of packet and data flow in the WIFI network
This is the protocol hierarchy in the WIFI. Questions asked are as follows:
Which packet size is most common in your trace buffer?
Data
Can you identify the type of communications seen in the trace buffer?
Yes
This is the IO graph of the WIFI. On the y axis are packets per second and the x-axis period (time). It shows the flow of the internet with specific time
ARP is a protocol used to translate the logical network address into the MAC physical link-layer address. The ARP plays an important role in ensuring that a local address is converted to a physical address and also provides the reverse of the process.
The ARP cache keeps static and dynamic ARP addresses. Every time a device in the network sends a message its IP address is kept in an ARP cache that can also be used to check for the performance of the network. A static address does change with time but is an address assigned to the devices by the network administrator. The dynamic address is normally assigned by the network devices such as the router. They normally last for a shorter time then they are reassigned. The ARP cache keeps all these addresses in
CMD command arp –a display of the internal and physical address of IP in the network. There is both static and dynamic IP address in the cache as shown in the screenshot.
when the arp-d command is run the cache deletes all the address that is currently in the cache as shown in the screenshot.
After deleting the ARP cache, a few IP addresses will be displayed as shown in the screenshot. One dynamic address and two static addresses will be displayed.
Pinging the local IP address will indicate success
The Wagga office requires 300 working stations, and we will use a class C subnet with a subnet mask of 255.255.254.0. To calculate the number of hosts, it will support us to use the formula 2n-2 where n is the number of zeros after converting the subnet mask to binary. The binary form is 11111111.11111111.11111110. 00000000.
29-2=510
The total number of hosts is 510, but since the workstations will be 300, the remaining will be used for future expansions because as time grows, the organisation grows. The IP address of the router will be 10.0.1.1, and the remaining workstations will get IP addresses from a pool of ranges within the subnet.
To be able to connect to the internet then the external IP address of the router will have to be in the same network as the IP address of the ISP router. In our case, our external IP will be 192.168.1.2.
The Junee office will use a class C subnet mask of 255.255.255.0, and we will calculate the number of hosts by converting it to binary which becomes 11111111.11111111.11111111. 00000000. Then the formula 2n-1 is used to calculate the number of hosts supported by this network.
28-2=254
Here we have 254 hosts in total supported, and since there are 130 workstations, for now, the remaining will be used for future expansions. The IP address to be assigned to the router will be 10.0.2.1. The remaining devices on the network will use the address range from 10.0.2.10 to 10.0.2.140.
To be able to connect to the internet then the external IP address of the router will have to be in the same network as the IP address of the ISP router. In our case, our external IP will be 192.168.1.3.
The Albury office has 125 workstations which will be accommodated by a class C subnet mask of 255.255.255.128. The number of hosts supported by this subnet is calculated by converting this subnet mask to binary which becomes 11111111.11111111.11111111.10000000.
27-2=126
The total number of hosts supported here is 126 and will be used by the devices in the network. The router will be assigned the IP address of 10.0.3.1, and the remaining devices will be assigned the IP addresses from the pool starting from 10.0.3.2 to 10.0.3.126.
To be able to connect to the internet then the external IP address of the router will have to be in the same network as the IP address of the ISP router. In our case, our external IP will be 192.168.1.4.
This office will require 120 workstations, and therefore we will use a subnet mask of 255.255.255.128 which is a class C subnet. We can then calculate the number of hosts supported by this subnet using the formula 2n-2.
The next thing is to convert the subnet mask to binary which becomes 11111111.11111111.11111111.10000000 and then count the number of zeros and substitute the value of n with the total number of zeros.
27-2=126
The number of hosts supported by this network is 126, and since we have 120 workstations, the remaining will be used to expand the network in future. The range from which the workstation will get IP address is 10.0.4.1 – 10.0.4.120. The IP address of the router will be 10.0.4.1.
To be able to connect to the internet then the external IP address of the router will have to be in the same network as the IP address of the ISP router. In our case, our external IP will be 192.168.1.5.
The subnet that will be used in this office is class C with the subnet mask of 255.255.255.0. To find the total number of hosts required on the network, we convert this subnet mask to binary which becomes 11111111.11111111.11111111. 00000000, and then we count the number of zeros. The formula used is 2n-2 where we n is the number of zeros we counted above.
28-2=254
The total number of hosts supported by this network is 254, and we have 215 working stations. Thus addresses not used will be reserved for future expansions. The IP addresses will range from 10.0.5.1 to 10.0.5.120, and the IP address for the router will be 10.0.5.1.
To be able to connect to the internet then the external IP address of the router will have to be in the same network as the IP address of the ISP router. In our case, our external IP will be 192.168.1.6.
The class C subnet is used with the subnet mask of 255.255.255.0 will be used to calculate the number of hosts to accommodate the workstations in this office. The subnet mask is converted to binary and becomes 11111111.11111111.11111111. 00000000. We then use the formula 2n-2 to calculate.
28-2=254
In this working station, we have only 140 devices on the network, and since the total supported is 254, then the remaining is reserved for future expansions. The IP addresses will range from 10.0.6.1 to 10.0.6.140, and the IP address for the router will be 10.0.6.1.
To be able to connect to the internet then the external IP address of the router will have to be in the same network with the IP address of the ISP router. In our case, our external IP will be 192.168.1.7.
If the number of hosts per network exceeds 1024, then the IP addresses will be exhausted. Hence the network will not expand. The design will have to be changed to use a different subnet that will accommodate more hosts. The solution to this problem can be super netting where a room for more addresses is created by using the bits of the next class if the eighth bits have been exhausted.
Carrell, J. L., Chappell, L., Tittel, E., & Pyles, J. (2013). Guide to TCP/Ip. Cengage Learning.
Neumann, J. C. (2015). The book of GNS3: Build virtual network labs using Cisco, Juniper, and more. San Francisco: No Starch Press.
S., G., K., S., K., & I. (2016, January 11). More than 255 Computers In My Network Networking. Retrieved from http://www.tomshardware.com/forum/28007-42-more -computers-network
The OSI Reference Model. (2018). Retrieved from https://www.erg.abdn.ac.uk/users/gorry/course/intro-pages/osi.html
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