FREE online courses on Internet Network of Networks - What is a Protocol - DoD Four-Layer Model

The Department of Defence Four-Layer Model was developed in the 1970s for the DARPA Internetwork Project that eventually grew into the Internet. The core Internet protocols adhere to this model, although the OSI Seven Layer Model is preferred for new designs. The DoD Four-Layer Model has been shown in Figure below.

 

Process                                                         

TELNET  FTP  SMTP

Host-to Host

TCP UDP

Internet

Network Access

Ethernet ARP  FDDI

Figure  DoD Four Layer Model

 

The four layers in the DoD model, from bottom to top, are:

1.  The Network Access Layer is responsible for delivering data over the particular hardware media in use. Different protocols are selected from this layer, depending on the type of the physical network.

2.  The Internet Layer is responsible for delivering data across a series of different physical networks that interconnect a source and destination machine. Routing protocols are most closely associated with this layer, as is the IP Protocol, the Internets fundamental protocol.

3.  The Host-to-Host Layer handles connection  basics, flow control, re-transmission of lost data, and other generic data flow management. The mutually   exclusive TCP and UDP protocols are this layers most important members.

4.  The Process Layer contains protocols that implement user-level functions, such as mail delivery, file transfer and remote login.