Osi Network Layers Review

OSI Layer Review

OSI Layer Review The following table compares the functions performed at each OSI model layer. Layer

Description and Keywords

Protocols z

z

Application z

Provides an interface for a service to operate Communication partner identification

z z z z

z

Presentation

z z z

Session

z

z

Transport

z z z

z

Network

z z z

Logical Link Control (LLC) Data Link

z z

Media Access Control (MAC)

z z z z z

Physical

z z

Data format (file formats) Encryption, translation, and compression Data format and exchange Keeps data streams separate (session identification) Set up, maintain, and tear down communication sessions Reliable (connection-oriented) and unreliable (connectionless) communications End-to-end flow control Port and socket numbers Segmentation, sequencing, and combination Logical addresses (host and network) Path determination (identification and selection) Routing packets Convert bits into bytes and bytes into frames MAC address, a.k.a. burned in address (BIA), hardware address Logical network topology Media access Host-to-host flow control Parity and CRC Move bits across the media Cables, connectors, pin positions Electrical signals (voltage, bit synchronization) Physical topology (network layout)

z z z z

z z

z z

z z z

z

z

z z z z

HTTP Telnet FTP TFTP SNMP JPEG, BMP, TIFF, PICT MPEG, WMV, AVI ASCII, EBCDIC MIDI, WAV Network File System (NFS) Apple Session Protocol (ASP)

TCP (connection-oriented) UDP (connectionless)

IP IPX AppleTalk

LAN protocols: 802.2 (LLC), 802.3 (Ethernet), 802.5 (Token Ring), 802.11 (Wireless) WAN protocols: PPP, Frame Relay, ISDN

EIA/TIA 232 (serial signaling) V.35 (modem signaling) Cat5 RJ45