Open Systems Interconnection (OSI) Supplemental Material

Internetworking

Open Systems Interconnection (OSI) zDeveloped by the International Organization for Standardization (ISO) in 1984 zThe primary architectural model for intercomputer communications. zA conceptual model composed of seven layers, each specifying particular network functions. zDescribes how information from a software application in one computer moves through a network medium to a software application in another computer.

OSI Model Application layer Network layer Data Link layer Physical layer OSI Model F-D’s Model Application layer: http, telnet, snmp, smtp, nfs, ftp TCP, UDP Data Link Layer Physical layer Internet Model IPv4, IPv6 (HDLC)

OSI Model zNetwork layer yprovides routing and related functions zTransport layer yimplements reliable internetwork data transport services zSession layer yestablishes, manages and terminates communication sessions between presentation layer entities zPresentation layer yprovides a variety of coding and conversion functions zApplication layer yclosest to the end user

Protocols zProtocols fall into one of the following groups: yLAN protocols yWAN protocols yNetwork protocols yRouting protocols

Interaction between Layers A data link layer contact three other layers

Headers and Data

Physical-layer Implementation

OSI Data Link Layer IEEE has subdivided data link layer into two sub-layers.