TCP/IP means Transmission Control Protocol and Internet Protocol. It is the network model used in the current Internet architecture as well. Protocols are set of rules which govern every possible communication over a network. These protocols describe the movement of data between the source and destination or the internet. These protocols offer simple naming and addressing schemes.

• Description of different TCP/IP protocols

  Layer 1: Host-to-network Layer

  i. Lowest layer of the all.

  ii. Protocol is used to connect to the host, so that the packets can be sent over it.

  iii. Varies from host to host and network to network.

  Layer 2: Internet Layer

  i. Selection of a packet switching network which is based on a connectionless internetwork layer is called a internet layer.

  ii. It is the layer which holds the whole architecture together.

  iii. It helps the packet to travel independently to the destination.

  iv. Order in which packets are received is different from the way they are sent.

  v. IP (Internet Protocol) is used in this layer.

  Layer 3: Transport Layer

  i. It decides if data transmission should be on parallel path or single path.

  ii. Functions such as multiplexing, segmenting or splitting on the data is done by transport layer.

  iii. The applications can read and write to the transport layer.

  iv. Transport layer adds header information to the data.

  Layer 4: Application Layer

  i. The TCP/IP specifications described a lot of applications that were at the top of the protocol stack. Some of them were TELNET, FTP, SMTP, DNS etc.

  ii. TELNET is a two-way communication protocol which allows connecting to a remote machine and run applications on it.

  iii. FTP(File Transfer Protocol) is a protocol, that allows File transfer amongst computer users connected over a network. It is reliable, simple and efficient.

  iv. SMTP(Simple Mail Transport Protocol) is a protocol, which is used to transport electronic mail between a source and destination, directed via a route.

  v. DNS(Domain Name Server) resolves an IP address into a textual address for Hosts connected over a network

  Merits of TCP/IP model

1. It operated independently.
2. It is scalable.
3. Client/server architecture.
4. Supports a number of routing protocols.
5. Can be used to establish a connection between two computers.

Demerits of TCP/IP

1. In this, the transport layer does not guarantee delivery of packets.
2. The model cannot be used in any other application.
3. Replacing protocol is not easy.
4. It has not clearly separated its services, interfaces and protocols.