The physical layer is responsible for the movement of individual bits from one hop (node) to the next

aliveboonevilleNetworking and Communications

Oct 28, 2013 (3 years and 7 months ago)

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OSI layers
-


1.

Physical


2.

Datalink


3.

Network


4.

Transport


5.

Session


6.

Presentation


7.

Application

Physical

Functions

Data is sent across physical media like wires and hubs. Responsible for encoding
scheme (like Manchester encoding) .

The physical layer is responsi
ble

for the movement of individual bits from one hop (node) to the next

Devices

Hubs, Repeaters, Amplifiers, Transceivers

Protocols

None

Datalink

Functions

Packets placed into frames at this layer. CRC is added at this layer. If CRC fails at
the receiving
computer, this layer will request retransmission. Mac addresses are
resolved at this layer.

Devices

Bridges, Switches.


Protocols

CSMA/CD

Network

Functions

Logical addressing, routing of message, determining the best route.

Devices

Routers.

Protocols

IP, I
PX, RIP, OSPF, ICMP, ARP, RARP, IGRP, BGP, EGRP

Transport

Functions

Sequencing, Error free delivery. Sliding window is at this layer.

The transport
layer is responsible for the delivery of a message from one process to
another

Devices

Gateways

Protocols

TC
P, UDP

Session

Functions

Responsible for opening, using and closing the session. Also places checkpoints
in the data flow, so that if the transmission fails, only the the data after the last
checkpoint needs to be retransmitted.

Devices

Gateways

Protocols

Network file system, SQL, RPC.
Remote Procedure Call

Presentation

Functions

Translating data into understandable format for transmission. Data compression
and encryption takes place at this layer. Redirector works at this layer.

Devices

Gateways

Protocols

J
PEG, MIDI, MPEG, (All kind of music, pictures and movie formats)

Application

Functions

Interface between the user and the computer. API incorporated in this layer.

Devices

Gateways

Protocols

SNMP, FTP, TELNET, WWW, HTTP, MIME