Lan Network Design For College Computer Science Essay

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In computer science, collection of interconnected computers that can share data, applications, and resources, such as printers. Computers in a LAN are separated by distances of up to a few kilometers and are typically used in offices or across university campuses. Wide Area Network, a computer network that is meant to cover a wide geographic area, usually over telephone lines, as compared to a local area network that operates in a single company or institution. The Internet is an interconnected web of wide area networks. In this project report we will develop a LAN for the it department and the connection with the University using WAN.

To develop a local area network for it department of 5 floors we have to select a suitable topology for our network. Connecting individual computers to each other creates networks. The Internet is a series of interconnected networks. Personal computers and workstations are connected to a Local Area Network (LAN) by either a dial-up connection through a modem and standard phone line or by being directly wired into the LAN. Other modes of data transmission that allow for connection to a network include T-1 connections and dedicated lines. Bridges and hubs link multiple networks to each other. Routers transmit data through networks and determine the best path of transmission. The first three octets of an IP address should be the same for all computers in the LAN. For example, if a total of 128 hosts exist in a single LAN, the IP addresses could be assigned starting with 192.248.248.x, where x represents a number in the range of 1 to 128. You could create consecutive LANs within the same company in a similar manner consisting of up to another 128 computers. Of course, you are not limited to 128 computers, as there are other ranges of IP addresses that allow you to build even larger networks.

Address ranges and LAN sizes:

There are three different classes of networks that determine the size and total possible unique IP addresses of any given LAN. For example, a class A LAN can have over 16 million unique IP addresses. A class B LAN can have over 65,000 unique IP addresses. The size of your LAN depends on which reserved address range you use and the subnet mask associated with that range.

Address range

Subnet mask


Addresses per LAN -

1 class A LAN

16,777,216 -

16 class B LANs

65,536 -

256 class C LANs


For our faculty network we will chose class c because we will need a lot of systems as subnets and we need more IP address so we will chose that class which can generates more IP addresses.

Network and broadcast addresses

Another important aspect of building a LAN is that the addresses at the two extreme ends of the address range are reserved for use as the LAN's network address and broadcast address. The network address is used by an application to represent the overall network. The broadcast address is used by an application to send the same message to all other hosts in the network simultaneously.

For example, we are using addresses in the range of to for our faculty network, the first address ( is reserved as the network address, and the last address ( is reserved as the broadcast address. Therefore, we only assign individual computers on the LAN IP addresses in the range of to

Network address:

Individual hosts: to

Broadcast address:

Subnet masks, Domain name and Hostnames:

Each host in a LAN has a subnet mask. The subnet mask is an octet that uses the number 255 to represent the network address portion of the IP address and a zero to identify the host portion of the address. For example, the subnet mask is used by each host to determine which LAN or class it belongs to. The zero at the end of the subnet mask represents a unique host within that network.

The domain name, or network name, is a unique name followed by a standard Internet suffixes such as .com, .org, .mil, .net, etc. You can give any name to your LAN if it has a simple dial-up connection and your LAN is not a server providing some type of service to other hosts directly. In addition, our faculty network is considered private since it uses IP addresses in the range of 192.248.248.x . Most importantly, the domain name of choice should not be accessible from the Internet if the above constraints are strictly enforced. Lastly, to obtain an "official" domain name you could register through InterNIC, Network Solutions or

Another important step in setting up a LAN is assigning a unique hostname to each computer in the LAN. A hostname is simply a unique name that can be made up and is used to identify a unique computer in the LAN. Also, the name should not contain any blank spaces or punctuation. For example, the following are valid hostnames that could be assigned to each computer in a LAN consisting of 5 hosts: hostname 1 - Aalam; hostname 2 - Adam; hostname 3 - Kamran; hostname 4 - Lindo; and hostname 5 - Nouman; hostname. Each of these hostnames conforms to the requirement that no blank spaces or punctuation marks are present. We have used short hostnames to eliminate excessive typing, and choose a name that is easy to remember.

Every host in the LAN has the same network address, broadcast address, subnet mask, and domain name because those addresses identify the network in its entirety. Each computer in the LAN has a hostname and IP address that uniquely identifies that particular host. The network address is / 24, and the broadcast address is Therefore, each host in the LAN must have an IP address between to 192.255.255.

There are two ways to assign IP addresses in a LAN. You can manually assign a static IP address to each computer in the LAN, or you can use a special type of server that automatically assigns a dynamic IP address to each computer as it logs into the network.

IP addresses for our LAN with 127 interconnected computer

IP address



Network address / 24

Same for all hosts

Domain name

Same for all hosts

Broadcast address

Same for all hosts

Subnet mask

Same for all hosts


Any name

Unique to each host

Host addresses


x must be unique to each host

Subnet Diagram for 5 Floors:

Floor IP Address

1st TO

2nd TO

3rd TO

4th TO

5th TO

We have to get a new range of IP address because we got more than 255 hosts in our domain.

Static IP addressing

In this type of address assigning technique a unique IP address is assignied to each and every computer in the local area Network. The first three octets must be the same for each host, and the last digit must be a unique number for each host. Furthermore, we also need to assign a unique hostname to each computer in our LAN. Each host in the LAN will have the same network address (, broadcast address (, subnet mask (, and domain name ( It's a good idea to start by visiting each computer in the LAN and jotting down the hostname and IP address for future reference.

Dynamic IP addressing

We can also use Dynamic IP addressing. We can do Dynamic IP addressing is using a server or host called DHCP (Dynamic Host Configuration Program) that automatically assigns a unique IP address to each computer as it connects to the LAN. There is also another server called BootP can also automatically assign unique IP addresses to each host in the network. The DHCP/ BootP service is a program that will act as a host with a unique IP address. An example of a DHCP device is a router that acts as an Ethernet hub (a communications device that allows multiple host to be connected via an Ethernet jack and a specific port) on one end and allows a connection to the Internet on the opposite end. Furthermore, the DHCP server will also assign the network and broadcast addresses. If we use dynamic addressing scheme we will not be required to manually assign hostnames and domain names.

The LAN hardware

If there we have not connected all computer together using any kind of hardware there will no use of assigning IP addresses to the hosts. We can connect the computers through different schemes such as Ethernet, Token Ring, FDDI, Token Bus, etc. Mostly Ethernet scheme is used to connect the hardware, we will also use this scheme for our network. Ethernet is available from several different computer vendors, and it is relatively inexpensive. Ethernet is a 10-Mbps baseband LAN specification developed by Xerox, Intel, and Digital Equipment. In order to build an Ethernet hub you need the following: an Ethernet Network Interface Card (NIC) for each computer, an Ethernet compatible hub with at least the same number of ports as there will be computers in the LAN, and Ethernet cables to connect each computer's NIC to the Ethernet hub.

We should also make sure that the hardware of choice is compatible with the Red Hat Linux operating system. This hardware/software compatibility information is usually found in the Requirements section on the back of the box of each product. Alternatively, we could ask a computer sales person about hardware/software requirements. We can usually save money by purchasing LAN cards as a package vs. purchasing them individually.

When choosing an Ethernet hub to ensure that it contains at least as many ports as there are computers that will participate in the LAN. We should choose such a hub which has additional ports to allow the future development. If we plan to use all of the computers in the LAN to access the Internet via a local Internet Service Provider (ISP), for this purpose we should use Router or Ethernet combo. The router or Ethernet unit is normally configured using any computer that is connected to the LAN. Assuming that all computers in the LAN will be running the Red Hat Linux operating system, a router will be required that can be configured using a Linux configuration program such as LinuxConf. For the future development we should choose the large Ethernet cable. Most of the Ethernet networks ese 10 base t cables with rj45 jacks. We should purchase cables which are double sized than the required length if we need the change in the LAN we could have enough cable for further development.

Hardware Installation:

Assuming that all LAN hardware is available, the next step is to install it. First turn off all the computers that will participate in the LAN. Next, open the case on each computer and install each NIC in the appropriate slot on the motherboard, being careful to follow the manufacturer's instructions.

Find a convenient but safe location for the Ethernet hub, preferably a centralized location in the same building or room along with the computers. Next, run the cable from the NIC in each computer to the Ethernet hub ensuring all cables are out of the way of users who will need physical access to each computer in the LAN. Moreover, make sure you follow all instructions provided with the LAN hardware before starting up any of the computers that will participate in the LAN.

We have used router to connect the LAN to the Internet or using a DHCP server, we have to do some configuration as required by the user's manual. Lastly, assuming all computers are attached to the Ethernet hub via the NIC and a specific port on the hub, we can now begin the software configuration process using the Red Hat operating system.

Network Diagram: