 the TCP/IP model. application also controls the session and presentation of data when required. The terms like socket and port that are associated with the session layer in an OSI model are used to describe the path over which applications communi- cate in TCP/IP model. Some of the protocols in this layer are FTP, HTTP, SMTP, and SNMP. 2. Transport layer: This layer of TCP/IP model performs functions similar to the transport layer of an OSI model. There are two important transport layer protocols, the transmission control protocol (TCP) and user datagram protocol (UDP). While TCP guarantees that information is received as it is a connection-oriented protocol, the UDP works on a connectionless setup suit- able for intermittent networks and performs no end-to-end reliability checks. Flow control is also performed at this layer to ensure that a fast sender will not swamp the receiver with message packets. Internet layer: This layer of the TCP/IP model performs functions similar to the network layer of an OSI model. The Internet layer is suited for packet switching networks and is mostly a connectionless layer that allows hosts to insert packets into any network and delivers these packets independently to the destination. The work of the Internet layer is limited to delivery of packets and the higher layers perform the function to rearrange the packets in order to deliver them to the proper application in the destination. The Internet protocol defines the packet format for the Internet layer. Routing of packets to avoid congestion is also handled in the Internet layer. This is a key layer of the TCP/IP model and all data has to pass this layer before being sent to lower layers for transmission. 4. Network interface layer: The physical layer and data link layer of the OSI model are grouped into a single layer called network interface layer in the TCP/IP model. This layer is used by the TCP/IP protocols running at the Seven-Layer Communication Model upper layers to interface with the local network. The TCP/IP model do