Overview of computer networks

In computer technology, the computer network is one of the vital fields where it is used to transmit the data and allow internet access .However the network implementation relies on various conceptual models referred to as the OSI and the TCP/IP models.

These models uses various layers in the process of transmitting the data over the network where the OSI model is Logical model which is more of theoretical while the TCP/IP model is more physical and is used to implement the OSI model and enables the internet connectivity.

1.

The computer network is a very essential tool which is highly used during the communication of network devices which assist in establishing the connection between the devices and enable transmission of data.

The computer network however uses two networking reference models which facilitates the connection and transmission of data over the models layers ,these two models are OSI and TCP/IP model and both has different function as below.

Open Systems Interconnection(OSI) model: This is a type of network model that was designed by International Organization for Standardization and it comprises of seven layers starting with physical layer and ends with applications layer, however this model describes the way the various software and hardware items that are involved in the networks communications shares the labor and are able to interact with each other.

Transport control protocol and internet protocol(TCP/IP):This is type of network model that was established by U.S. Department of Defense which comprises of two types of  networks standards that mainly defines the internet ,the IP is used to give definition of how the computer in network gets data to one another through a network which is routed and interconnected while the TCP gives the good definition of the way applications do creates a channel of communication which is reliable through the network. Therefore the IP define the address and routes and the TCP define the network conversations over the network without garbling and loss of data.

The two type of network models have some similarities and also they differ in some cases as discussed below.

Comparison

1.The OIS model and the TCP/IP models has some common features as compared in the below similarities.

2.They both architectures which are in layers form.

3.The Layers in both models provides functions with similarity.

4.The both models have protocols stacks.

5.They are both type of the reference models.

6.The IP in the TCP/IP model do correspond with OSI Layer 3 which is called the network layer.

7.The TCP in the TCP/IP model do correspond with OSI Layer 4 which is transport layer and Layer 5which is session layer.

OSI model

Contrasts

However the two layers have some differences in both structure and the layering as discussed here below.

Diagram of the OSI and the TCP/IP models.

(William, 2014).

Differences between OSI and TCP/IP models.

The table below shows the major difference between the IOS and the TCP/IP network models.

OSI(Open System Interconnection)	TCP/IP(Transmission Control Protocol / Internet Protocol)
1. OSI is generic model, protocols independent standards, and acts like communications gateways from the networks and end users.	1. TCP/IP is a model which is based on standards protocol which is used to develop internet and is communications protocol that  allows the hosts to be connected in a network.
2. In OSI model packet is delivered through the transport layer.	2. In TCP/IP model the packet is not delivered through the transport layer since the TCP/IP model is reliable.
3.The OSI model uses the  vertical approach.	3. The TCP/IP model uses the horizontal approach.
4In  OSI model  the  Presentations and Sessions layers are both separated	4. In TCP/IP there is no separated presentations or sessions layer.
5. In OIS model the Transport Layer is connections oriented and responsible to establish connections.	5. In TCP/IP  the Transport Layer is both Connections Oriented and Connections  less.
6. In OIS model the Network Layer is both connections Oriented and connections less.	6. In TCP/IP  the Network Layer is connections less.
7. The OSI model act as a referencing model which is used to build networks and acts as guidance tools.	7.The TCP/IP model is used to implement the OSI model.
8. The OSI model Network layer is used in provision connections oriented and connections less services.	8. The TCP/IP model Network layer is used to provide connections less services.
9. The OSI model there is a challenge while fitting the protocols to the model.	9. In TCP/IP model there is no fitting of any protocol.
10. In the OSI model there are protocols which are hidden and are easy to replace in case the technology change.	10. In TCP/IP model it is quite hard to replace the protocols even if technology changes.
11. In the OSI model there are clear definition of service, interface, and the protocol and the model is protocols independent.	11. In TCP/IP model there is no clear separation between  service, interface and protocol and thus the model is protocols dependent.
12. The OSI model is made of 7 layers.	12. The TCP/IP is made of 4 layers.
13. The OSI model is type of conceptual models.	13. The TCP/IP type of a clients-servers model.
14. The OSI Model is not physically tangible	14. The TCP/IP Physical and also Tangible.
15. The OSI Model follow the bottom-up approaches.	15. The TCP/IP follows a top to bottom approaches.

Best model

In the network design the OSI model is used as the reference model which is logical and much of theoretical but the TCP/IP is used in the implementing this theoretical model and the internet transmission mainly occurs in this layer ,therefore the TCP/IP model is more better model since it is more physical than theoretical and is used in actual internet connectivity.

2.

Hands-On Project 2-3

1.Open browser.

3.Select IPV4 option

6.Close the browser.

Hands-On Project 2-5.

Open the browser.

Press enter key.

Record new values of

Subnet mask: 255.255.255.192
Subnet bits:2
Mask bits:26
Hosts per subnet:62
Host address range: 192.168.0.1-192.168.0.62
Broadcast address: 192.168.0.63

Select network class A radio button in the subnet calculator interface.

Open the subnet mask dropdown list and change mask  to 255.255.0.0.
Write down values for:
Subnet bits:8
Maximum subnets:256
Mask bits:16
Hosts per subnet:65534
Host address range:10.0.0.1-10.0.255.254
Broadcast address10.0.255.255

While comparing the two cases the subnet bits , Hosts per subnet and Maximum subnets values are higher in the second scenario while Mask bits is smaller in the second scenario compared with first scenario.

Closing the browser after comparison.

3.

The Address Resolution Protocol (ARP)  that was discovered in 1982 by RFC internet standards are types of communications protocols  that are used to discover the linking layer addresses ,which includes the MAC addresses which is a hardware’s addresses and is obtained from the IP addresses which has associations with the respective networks layer addresses and mainly IPV4 addresses.

This protocol works using some two types of messages which includes:

1. ARP requests-This message broadcasts to the devices that are connected in the network.
2. ARP reply-This is the message that is uni-casted to the device that requested a message.

Purpose of the ARP Cache

In the ARP there is the ARP cache that is a form of table that mainly used to store the correlated MAC addresses and the respective IP addresses that corresponds to it.

4.

The Foreshore IT Solutions is a growing organization that had expanded to total of six sites and in these sites there are number of computers that are connected in the network where the computers in each sites were as follows  in the  finance office 260 ,IT call centre 520 ,Research and development office 120,marketing department 40 ,information technology  130 and head office 60 computers (Tom , 2015).

In order to come up with the entire network system there will be designing of the network subnets for each site in the network and they will be connected to the other subnets through the routers as the network devices.

TCP/IP model

In the design of the respective network subnets the private address 10.0.0.0 is the one which is going to be used and the subnets designed will be able to allow expansion of the network in near future and they will be able to accommodate the respective number of hosts.

However after full implementation of the entire network subnets the whole network will be having a total of 1200 hosts and the subnets will be able to accommodate more in case the organization expands in future.

Below is the network diagram of the proposed organization network.

Detailed  design of a simple addressing solution

Network diagram.

Subnet IP address calculation.

Each of the network subnet has will be utilizing the private network ip address 10.0.0.0 where the subnet derived will be having the Network ID, ip address ,subnet mask address, and the gateways (Forouzan, 2014).

Subnet1:Finance Office – 260 workstations 

step 1: calculate the ip address of subnet 1

Number  of hosts=260 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 260 hosts in subnet 1 therefore  2^x-2=260.

2^x=260+2.

2^x=262

Therefore x=9 since 262<(2⁹=512)

step 2: calculate the network prefix (/p) of subnet 1

since mask length = 32 bits,

Network  prefix (p) is  calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network  prefix is 32-9=23.

Therefore since the Network ID for subnet1 is 10.0.0.0 and the network prefix is /23 then the ip address of the subnet1 is 10.0.0.0/23.

step 3: calculate the subnet mask for subnet 1.

Given the ip address of subnet1 is 10.0.0.0/23.

The subnet mask of subnet1 is

 1111 1111. 1111 1111. 1111 1110.0000 0000 or 255.255.254.0.

step 4: summary of the subnet1 ip addresses.

Network ID	Ip address	Subnet mask address	Ip addrees range
10.0.0.0	10.0.0.0/23	255.255.254.0	10.0.0.1 to 10.0.0.512

Subnet2:IT Call Centre – 520 workstations .

step 1: calculate the ip address of subnet2.

Number  of hosts=520 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 520  hosts in subnet 2 therefore  2^x-2=520.

2^x=520+2.

2^x=522

Therefore x=10 since 522<(2¹⁰=1024)

step 2: calculate the network prefix (/p) of subnet2.

Since mask length = 32 bits,

Network prefix (p) is calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network prefix is 32-10=22.

Therefore since the Network ID for subnet1 is 10.0.1.0 and the network prefix is /22 then the ip address of the subnet2 is 10.0.1.0/22.

Comparison of OSI and TCP/IP models

step 3: calculate the subnet mask for subnet2.

Given the ip address of subnet2 is 10.0.1.0/22.

The subnet mask of subnet2  is

 1111 1111. 1111 1111. 1111 1100.0000 0000 or 255.255.252.0.

step 4: summary of the subnet2 ip addresses.

Network ID	Ip address	Subnet mask address	Ip address range
10.0.1.0	10.0.1.0/23	255.255.252.0	10.0.1.1 to 10.0.0.1024

Subnet3:Research and Development Office – 120 workstations 

step 1: calculate the ip address of subnet3.

Number  of hosts=120 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 120  hosts in subnet 3 therefore  2^x-2=120.

2^x=120+2.

2^x=122

Therefore x=7 since 122<(2⁷=128)

step 2: calculate the network prefix (/p) of subnet3.

Since mask length = 32 bits,

Network prefix (p) is calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network prefix is 32-7=25.

Therefore since the Network ID for subnet3 is 10.0.2.0 and the network prefix is /25 then the ip address of the subnet3 is 10.0.2.0/25.

step 3: calculate the subnet mask for subnet3.

Given the ip address of subnet3 is 10.0.2.0/25.

The subnet mask of subnet3  is

 1111 1111. 1111 1111. 1111 1111.1000 0000 or 255.255.255.128.

step 4: summary of the subnet3 ip addresses.

Network ID	Ip address	Subnet mask address	Ip address range
10.0.2.0	10.0.2.0/25	255.255.255.128	10.0.2.1 to 10.0.2.128

Subnet4: Marketing Department – 40 workstations 

step 1: calculate the ip address of subnet4.

Number  of hosts=40 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 40  hosts in subnet 3 therefore  2^x-2=40.

2^x=40+2.

2^x=42

Therefore x=6 since 42<(2⁶=64)

step 2: calculate the network prefix (/p) of subnet4.

Since mask length = 32 bits,

Network prefix (p) is calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network prefix is 32-6=26.

Therefore since the Network ID for subnet4 is 10.0.3.0 and the network prefix is /26 then the ip address of the subnet4 is 10.0.3.0/26 (Douglas, 2017).

step 3: calculate the subnet mask for subnet4.

Given the ip address of subnet4 is 10.0.3.0/26.

The subnet mask of subnet4  is

 1111 1111. 1111 1111. 1111 1111.1100 0000 or 255.255.255.192.

step 4: summary of the subnet3 ip addresses.

Network ID	Ip address	Subnet mask address	Ip address range
10.0.3.0	10.0.3.0/26	255.255.255.192	10.0.3.1 to 10.0.3.64

Subnet5: Information technology – 130 workstations .

step 1: calculate the ip address of subnet5.

Number  of hosts=130 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 130  hosts in subnet 5 therefore  2^x-2=130.

2^x=130+2.

2^x=132

Therefore x=8 since 132<(2⁸=256)

step 2: calculate the network prefix (/p) of subnet5.

Network design and implementation

Since mask length = 32 bits,

Network prefix (p) is calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network prefix is 32-8=24.

Therefore since the Network ID for subnet4 is 10.0.4.0 and the network prefix is /24 then the ip address of the subnet5 is 10.0.4.0/24.

step 3: calculate the subnet mask for subnet5.

Given the ip address of subnet5 is 10.0.4.0/24.

The subnet mask of subnet5  is

 1111 1111. 1111 1111. 1111 1111.0000 0000 or 255.255.255.0.

step 4: summary of the subnet5 ip addresses.

Network ID	Ip address	Subnet mask address	Ip address range
10.0.4.0	10.0.4.0/24	255.255.255.0	10.0.4.1 to 10.0.4.256

Subnet6: Head Office – 60 workstations.

step 1: calculate the ip address of subnet6.

Number  of hosts=60 hosts.

Private ip address =10.0.0.0

Formula  :2^x-2=number of hosts

X is the value of host bits length.

We require 130  hosts in subnet 6 therefore  2^x-2=60.

2^x=60+2.

2^x=62

Therefore x=6 since 62<(2⁶=64)

(Behrouz , 2016)

step 2: calculate the network prefix (/p) of subnet6.

Since mask length = 32 bits,

Network prefix (p) is calculated as follows:

32-x=p, where x is the host value length and p is the network prefix.

The Network prefix is 32-6=26.

Therefore since the Network ID for subnet6 is 10.0.5.0 and the network prefix is /26 then the ip address of the subnet6 is 10.0.5.0/26.

step 3: calculate the subnet mask for subnet6.

Given the ip address of subnet6 is 10.0.5.0/26.

The subnet mask of subnet6  is

 1111 1111. 1111 1111. 1111 1111.1100 0000 or 255.255.255.192.

step 4: summary of the subnet6 ip addresses.

Network ID	Ip address	Subnet mask address	Ip address range
10.0.5.0	10.0.5.0/26	255.255.255.192	10.0.5.1-10.0.5.64

What happens to design if hosts number per network jumps to over 1,024.

In the case of the host per building happens to exceed 1024 hosts the only solution is to change the subnet mask address to another subnet address that will be able to accommodate those devices, however in the connection one will require to use more connection devices like the number of switches will be increased as well (Andrew , 2015).

Conclusion

The computer network is a field that is essential in data transmission and it highly rely on the two main conceptual models which includes OSI and the TCP/IP model which provides the logical and physical network designs.

In the area of network design where there are various branches of network the network require to be split into small network units called the Subnets ,the subnets utilizes common private network and they require to be designed well to accommodate all hosts and allow area of expansion without wasting any address .

References

Andrew ,S(2015).Computer Networks. New York:

Prentice Hall.

Behrouz ,A.(2016).Data Communication and Networking.New York:

McGraw-Hill Education.

Douglas,C(2017).Internetworking with TCP/IP, Volume 1. California:

Addison-Wesley Professional.

Forouzan,I.(2014). Computer Networks: A Top – Down Approach.

New York: McGraw-Hill .

Tom ,C.(2015).IPv6 Address Planning: Designing an Address Plan for the Future.

San Francisco: O’Reilly Media

William,S.(2014). Data and Computer Communication. New Delhi:

Tata McGraw Hill.