• The TCP IP protocol was developed prior to the OSI model. The layers in the TCP/ IP protocol suite do not exactly match those in the OSI model. The original TCP/IP protocol suite was defined as having four layers: host-to-network, internet, transport, and application. However, when TCP/IP is compared to OSI, we can say that the TCP/IP protocol suite is made of five layers: physical, data link, network, transport, and application.
- TCP stands for Transfer control protocol.
- IP stands for internet protocol.
1. Physical and Data Link Layers
- The physical layer specifies the work and characteristic of computer hardware which is used for the network.
- The data link layer has two sublayers 1. logical link control (LLC) 2. media access control (MAC)
2. Network Layer
a. Internet protocol(IP)
- The Internetworking Protocol (IP) is the transmission mechanism used by the TCP/IP protocols.
- It is an unreliable and connectionless protocol-a best-effort delivery service.
b. Internet Control Message Protocol (ICMP)
- The Internet Control Message Protocol (ICMP) is a mechanism used by hosts and gateways to send notification of datagram problems back to the sender. ICMP sends query and error reporting messages.
c. Internet Group Multicast Protocol(IGMP)
- The Internet Group Message Protocol (IGMP) is used to facilitate the simultaneous transmission of a message to a group of recipients.
d. Address Resolution Protocol (ARP)
- The Address Resolution Protocol (ARP) is used to associate a logical address with a physical address. ARP is used to find the physical address of the node when its Internet address is known
e. Reverse Address Resolution Protocol (RARP)
- The Reverse Address Resolution Protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.
3. Transport Layer
- Transport layer was represented in TCP/IP by two protocols: TCP and UDP.
- Provides full transport-layer services to applications. TCP is a reliable stream transport protocol. The term stream, in this context, means connection-oriented:
- It is a process-to-process protocol that adds only port addresses, checksum error control, and length information to the data from the upper layer.
c. SCTP (Stream Control Transmission Protocol)
- SCTP provides support for newer applications such as voice over the Internet.
4. Application Layer
- It is equivalent to the combined session, presentation, and application layers in the OSI model.