Explain the architecture of the TCP/IP protocol suite.

The TCP/IP protocol suite also known as a DARPA model was named  after the U.S. government agency that initially developed TCP/IP. There are four different layers in the TCP/IP reference model:

• ·        Application
• ·        Transport
• ·        Internetwork
• ·        Network Interface and Hardware

Network Interface layer :

The Network Interface layer (also called the Network Access Layer) sends TCP/IP packets on the network medium and receives TCP/IP packets off the network medium. TCP/IP was designed to be independent of the network access method, frame format, and medium. Therefore, you can use TCP/IP to communicate across differing network types that use LAN technologies such as Ethernet and 802.11 wireless LAN and WAN technologies such as Frame Relay and Asynchronous Transfer Mode (ATM).

Internet Layer:

The Internet layer responsibilities include addressing, packaging, and routing functions. The Internet layer is analogous to the Network layer of the OSI model. The internet layer provides a datagram service. Datagram is a packet of information that comprises a header, data, and a trailer. The header contains destination address, source address and security labels. The trailers contain a checksum value, which is used to ensure that the data is not modified in transit. The Internet layer protocols pack the message in a datagram and sent it off. For each message to be transmitted using the datagram services must specify destination address and data. A datagram service does not support for a connection oriented services.

The core protocols for the IPv4 Internet layer consist of the following:

·        Address Resolution Protocol (ARP)

·        The Internet Protocol (IP)

·        The Internet Control Message Protocol (ICMP)

·        The Internet Group Management Protocol (IGMP)

Transport Layer:

The Transport layer (also known as the Host-to-Host Transport layer) provides the Application layer with session and datagram communication services. The Transport layer encompasses the responsibilities of the OSI Transport layer. The core protocols of the Transport layer are TCP and UDP. TCP provides a one-to-one, connection-oriented, reliable communications service. TCP establishes connections, sequences and acknowledges packets sent, and recovers packets lost during transmission. In contrast to TCP, UDP provides a one-to-one or one-to-many, connectionless, unreliable communications service.

Application Layer:

The Application layer allows applications to access the services of the other layers, and it defines the protocols that applications use to exchange data. The Application layer contains many protocols, and more are always being developed. The most widely known Application layer protocols help users exchange information:

• 
  
• ·        Hypertext Transfer Protocol (HTTP)
• ·        File Transfer Protocol (FTP)
• ·        Simple Mail Transfer Protocol (SMTP)
• ·        Domain Name System (DNS)
• ·        Routing Information Protocol (RIP)
• ·        Simple Network Management Protocol (SNMP)