5-Application:
Provides network services to application processes (email, file transfer, etc.)
Interacts with operating system and interfaces with system (FTP, Telnet, SMTP)
Handles general network access, flow control, error recovery, and file transfer
Agreement procedures for error recovery and controls data integrity
Responsible for meaningful exchange of data
Ensures data is readable by receiver
Format of data/data structures
Negotiates data transfer syntax for application layer
Provides encryption, text compression, and reformatting? Support of connections between sessions, administrative tasks, and security
Control structure for communication between applications
Establishes, manages, and terminates connections between applications
Data expeditions, class of service, exception reporting
Inter-host communication
4-Transport:
Responsible for reliable, transparent transfer of data between end points
End-to-end error recovery and flow control
Packet handling, repackaging of messages, dividing messages into smaller packets, and error handling
Concerned with transportation issues between hosts
Establishing, maintaining, and terminating virtual circuits
Fault detection and recovery
Deals with segments
3-Network:
Responsible for addressing and control functions (routing)
Establishing, maintaining, and terminating connections (packet switching, routing, data congestion, reassembly of data, translation of logical addresses to physical addresses)
Provides connectivity and path selection between two end systems
Domain of routing
Deals with packets
2-Data Link:
Responsible for error-free transmission and establishing logical connections between stations
Packaging raw bits of data from physical into blocks of data (frames)
Sending frames with necessary synchronization, error control, and flow control
Physical addressing, network topology, and media access (interface to cable)
Reliable transfer of data, error notification, and flow control
1-Physical:
Responsible for the transmission of unstructured bit streams over physical media
Defines the mechanical, electrical, and procedural characteristics required to establish, maintain, and deactivate physical links of end systems
Describes the media
Wires, connectors, voltages, data rates, and binary transmission