TCP/IP Model

, , 

* Was created by the Department of Defense in the 1970s
* Is a reduced version of the OSI Model
* Is based on and around the TCP/IP Protocol suite.
  • TCP/IP Model has four layers :
    • Application Layer
    • Transport Layer
    • Internet Layer
    • Network access or network interface layer
  • All TCP/IP protocols are located on the top three layers.
  • Protocols located on bottom layer are not part of the TCP/IP suite.
  • Each layer corresponds to one or more OSI model layers.

Common TCP-IP Protocols

Layer 1 - Application Layer

1
2
* Defines protocols, services, and processes that allow programs and users to interface with the network
* Defines how programs interface with the Transport Layer services to use the network

Common Application Layer Protocols :

  • HTTP
  • Telnet
  • FTP
  • TFTP
  • SNMP
  • DNS
  • SMTP
  • DHCP
  • …

Layer 2 - Transport Layer

1
2
* Provides communications session management between host computers
* Defines level of service and status of connections used when transporting data

Common Transport Layer Protocols :

  • TCP
  • UDP
  • RTP
  • …

Layer 3 - Internet Layer

1
2
3
4
* Internet layer packages data into IP datagrams called packets
* Header of packet contains Source and Destination information
* Internet Layer uses this information to forward packets between hosts across the network
* It performs routing of IP packets

Common Internet Layer Protocols :

  • IP
  • ICMP
  • ARP
  • RARP
  • …

Layer 4 - Network Interface Layer

1
2
3
4
5
* Sometimes called Network Access Layer.
* Specifies how data is physically sent through a network.
* Specifies how bits are electrically signaled by hardware.
* Defines how hardware devices interface with network medium.
* Example : Coaxial cable, optical cable, and twisted pair cable.

Standards Defined by This Layer :

  • Ethernet
  • Token Ring
  • FDDI
  • X.25
  • Frame Relay
  • RS-232
  • V.35
  • …