Communication and Internet Technology

Isolated Networks

#  Requirement for Network communication:

  1. Sender
  2. Receiver
  3. Transmission Medium
  4. Protocol
  5. Message

Network Topology:

There are several possible ways for computers to have a local network. These are;

a. P2P Network (A point-to-point network)

  1. Direct communication with one computer to another computer.
  2. Connected with the end-point system.
  3. A dedicated link between two networks.

b. Bus Network

  1. Different computers connected by a single line of cable.
  2. Indirect connection between computers in between end-point system.
  3. The main single cable receives and sends message from one node to another node.

c. Ring Topology

  1. In this topology, each computer is connected to its adjacent two computers.
  2. The connection is in the formation of a ring, where each computer is connected with another.
  3. Communication between any two computers goes through a same direction.

d. Star Topology

  1. The computers in this topology are point-to-point connected with a central device.
  2. Communication channel between two computers goes through the central device, where it can also act as a ring topology if properly installed.
  3. Dominant configuration as it allows to communicate with other networks.

Key points:

  • Bus and Ring typologies were the earliest network configuration, where connected computers would have been workstation and others would be servers.
  • Mesh topology (where each and every computer is connected with each other) would be difficult to implement because of the number of cables required to install.
  • Most widely used network system nowadays would be Star Topology as it is easier to communicate with other networks.  

Protocol Suite

A protocol is a set of rules set that the sender and receiver have to follow for communication. In the communication network, generally, there are two types of protocol, i.e. TCP/ IP protocol for the internet activity.

TCP/ IP suite includes the following protocols, they are;

  1. Application Layer: HTTP, SMTP, DNS< FTP, POP3
  2. Transport Layer: TCP, UDP, SCTP
  3. Network Layer: IP, IGMP, ICMP, ARP

How does protocol work?

  1. A sender sends message through an application protocol which is then delivered to transport protocol on the same system.
  2. Transport protocol then identifies the same protocol on the receiver end on the application level.
  3. Then the application protocol receives the identical message from the transport protocol in the receiver end.

TCP (Transmission Control Protocol)

  1. TCP is a connection-oriented model system that only functions only after stable connection is established between sender and receiver.
  2. Initially, an end-system sends an initial sequence of packets to the network side. Once the connection is established it sends other packets to the receiver-end in sequential manner.
  3. TCP protocol sends information in smaller packets so that the data has enough space to be stored for guarantee safety of delivery.
  4. When data is stored in packets, it contains a (header and user data). The header includes the sequential number and port number in order to decode and re-assemble the user data in the receiver-end.
  5. After sending the data, it receives a response for acceptance. This allows us to identify any missing packets to resend.

IP Protocol (Internet Protocol)

  1. Internet Protocol is includes in network layer, after data is received from transport layer, it is then added a further header.
  2. This header includes the IP address of the sender and receiver. For the transmission of data to the receiver end, DNS system is used that match to the user link.
  3. Data in IP is send in packets to transport layer, which is then assembled again to the receiver-end.
  4. After the data packets are sent to the transport layer, IP has no further responsibility. If any data packets is remaining from previous data transmission, it sends it to TCP or transport layer.

 Application layer service:

A DNS (Domain Name Service) is given to the name that is associated with the IP address that is the identity of a site. Among the application protocols, there are generally five protocols given in the list below.

  1. HTTP (Hyper-Text Transfer Protocol):

Considered important protocol in application layer protocol to access the website through a browser.

How HTTP works

a. A server receives a lot of requests from different computers, then for identifying the specific services such as DNS, web-services, servers use well-known ports. For example, for using the web services such as HTTP service, port number 80 is used.

b. HTTP sends a request message to the TCP because HTTP is not a reliable protocol itself, therefore it uses TCP to use the functionality of sending packets.

c. TCP makes smaller packets to the IP address of the web page for the establishment of the connection.

d. The server of the webpage receives a lot of requests from different computers, then for identifying the specific services such as DNS, web-services, servers use well-known ports. For example, for using the web services such as HTTP service, then the port number 80 is used.