APPLICATION LAYER

LAYER 7 THIS LAYER INTERFACES DIRECTLY TO THE APPLICATION AND PERFORMS COMMON APPLICATION SERVICES FOR THE APPLICATION PROCESSES.

NO PROTOCOLS

PRESENTATION LAYER

LAYER 6

THE PRESENTATION LAYER RELIEVES THE APPLICATION LAYER OF CONCERN REGARDING SYNTACTICAL DIFFERENCES IN DATA REPRESENTATION WITHIN THE END-USER SYSTEM.

PROTOCOLS: POP,SMPT,DNS,FTP,Telnet,ARP

SESSION LAYER

LAYER 5. THE SESSION LAYER PROVIDES THE MECHANISM FOR MANAGING THE DIALOGUE BETWEEN END-USER APPLICATION PROCESSES. THE SESSION LAYER HOLDS THE CHANNEL OPEN.

PROTOCOL: NetBIOS

TRANSPORT LAYER

LAYER 4. THIS LAYER PROVIDES END-TO-END COMMUNICATION CONTROL. IT IS A VIRTUAL CIRCUIT.

PROTOCOL: TCP

NETWORK LAYER

LAYER 3. THIS LAYER ROUTES THE INFORMATION IN THE NETWORK.

PROTOCOL: IP, ICMP

DATA LINK LAYER

LAYER 2.  THIS LAYER DESCRIBES THE LOGICAL ORGANIZATION OF DATA BITS TRANSMITTED ON A PARTICULAR MEDIUM. DATA LINK IS DIVIDED INTO TWO SUBLAYERS: THE MEDIA ACCESS CONTROL LAYER(MAC) AND THE LOGICAL LINK CONTROL LAYER(LLC).

PROTOCOLS: SLIP, PPP

PHYSICAL LAYER

LAYER 1.  THIS LAYER DESCRIBES THE PHYSICAL PROPERTIES OF THE VARIOUS COMMUNICATIONS MEDIA, AS WELL AS THE ELECTRICAL PROPERTIES AND INTERPRETATION OF THE EXCHANGED SIGNALS. THE PHYSICAL LAYER IS THE ACTUAL NIC, ETHERNET CABLE, AND SO FORTH.

PROTOCOLS: NONE

OSI MODEL

THE OPEN SYSTEMS INTERCONNECT MODEL.

THIS MODEL IS A DESCRIPTION OF HOW THE NETWORKS COMMUNICATE. IT DESCRIBES THE VARIOUS PROTOCOLS AND ACTIVITIES, AND DELINEATES HOW THE PROTOCOLS AND ACTIVITIES RELATES TO EACH OTHER.