TCP/IP Protocol Suite


OSI is a reference model it is not actually a implemented model. TCP/IP is actually implemented the model. TCP/IP refer to a suite of data communication protocols. TCP/IP have two zones protocol that composes the suite.

Here in this gate study material for computer science we will study about different protocols used at different layers of TCP/IP model. We will also study their functionality at the corresponding layer.



TCP/IP Model



TCP/IP protocol suite has five layers as shown in the figure. Different types of protocols used at different  layers of TCP/IP Protocol suite as shown in the figure are explained as follows:

1.      Protocols for physical and  Data Link Layer

At physical and data link layer TCP/IP protocol suite does not define any specific protocol. It supports all standard protocols. A network in TCP/IP interwork can be a LAN( local area network ) or a wide area network.

2.      Protocols used at Network Layer

At the network layer or internetwork layer, TCP/IP protocol support Internetworking Protocols(IP) . which provides basic packet delivery services for all the TCP/IP networks.

 Since the basic functionalities of Internetworking Protocol (IP)  are as follows

a.       It defines the datagram which is the basic unit of the data transmission on the internet.  IP support the data in the packet each of which is known as datagram and it is transported separately.

b.      The datagram can travel along the different route and arrive out of sequence. And even datagram may be received duplicated.

c.       IP protocol does not keep the track of the route or reordering the datagram.

                d.      IP protocol defines the internet addressing scheme which is system of logical host addresses

E.     IP protocol is responsible for moving the data between the network layer and host to host transport layer.

f.       Internet protocol route the datagram to the remote host.

g.      IP protocol is also responsible for fragment and reassembles the datagram.

                     Internetworking protocol also contain four supporting protocols named as ARP, RARP,   IGMP and ICMP.

a)      Address resolution protocol (ARP)

Address resolution protocol is used to associate an IP address with a  Physical address. ARP is used to find the physical address of a node when the logical address is known.

b)      Reverse address resolution protocol (RARP)

RARP reverse address resolution protocol is used to find the internet address or logical address of a host when its physical address is known. It is generally used when a computer is connected first time to the network.

c)      Internet control message protocol( ICMP)

ICMP protocol proved a mechanism by which is used by a host and gateway to send notification of datagram related problem back to the sender. ICMP send query and error reporting message

d)     Internet group management protocol (IGMP)

The internet group management protocol is a  protocol which is used by a host and its adjacent routers on IP Network to establish multicast group membership.

3.      Protocols at Transport Layers

Transport layer provides two protocols in TCP/IP suite. These protocols are TCP and UDP. UDP and TCP are the protocols which are responsible for delivery of the entire message from a process to another process.

(a) Transmission  Control Protocol

TCP is a reliable stream transport protocol. In this context, the meaning of the term stream is connection oriented. A connection must be established between both end of transmission before either end can transmit the data. At the sending end of each transmission, TCP divides a stream of data into a smaller unit which is known as the segment.

Each segment has a sequence number for reordering at the receiver side.

Segments are carried across the internet inside the IP datagram.

At receiving end TCP collect each datagram as it comes in and reorders the transmission based on sequence numbers.

(b) User Datagram Protocol

  • User datagram protocol is an alternative to TCP protocol.  Unlike TCP UDP is connectionless.  UDP does not acknowledge or guarantee delivery and does not provide sequencing of the packet.
  • The application itself must process any error and check for reliable delivery.
  • UDP is specially used for real-time audio and video where packets are simply ignored. Because there is time to retransmit.


4.      Protocol used in Application Layer

       The most widely used and implemented transport layer protocols are

a)      File Transfer Protocol (FTP): it performs basic interactive file transfer between the protocol.

b)      Telnet: Telnet enables users to execute terminate the session between remote host. It provides remote login facility.

c)      Simple Mail Transfer protocol(SMTP) : It support basic email delivery services.

d)     Hypertext transfer protocol: It supports the low overhead transport of files which consist a mixture of text and image.

e)      Domain Name Service( DNS):  it is also known as name services. This basically maps the IP address to the name assigned to the device.

f)       Routing Information Protocol(RIP): It is used by the network device to exchange routing information.

g)      Simple Network Management Protocol (SNMP): This is a protocol which is used to collect the management information from the network devices.

h)      Network File System (NFS):  It is system developed by the Sun Microsystems that  enable the computer to mount drive on remote host and operate them as if they are on local drives.

Later we will study these protocols in more details. I hope this Computer Science Study Material for Gate will be beneficial for you dear gate aspirants. 


All the Best !


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