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Back to basics : Networking - Part 1

Range of different classes of IP addresses:

Based on the range of first octet
Class A:  1-126
Class B:  128-191
Class C: 192-223

Private IP ranges

Class A: 10.0.0.0 to 10.255.255.255
Class B:172.16.0.0 to 172.31.255.255
Class C: 192.168.0.0 to 192.168.255.255

APIPA address: 169.254.0.0 to 169.254.255.255

MAC address:

Media access control addree is associated with a  network adapater, often known as hardware address

12 digit hexadecimal, 48 bits in length

Written in format- MM:MM:MM:SS:SS:SS

First half is address of the manufacturer and second half is serial number assigned to adapter by manufacturer

MAC address work at layer 2, Ip address at layer 3

OSI Model:(Open System Interconnection)

 Physical: Defines the physical media ie cables, connectors etc

Data Link: defines data format.Converts raw bits from physical layer to data frames for delivery to network layer. Common devices that work at this layer: Switch

Network layer: Addressing, determining routes,subnet traffic control etc. IP addresses are added at this point and data at this layer is called packet. Common device at this layer: Router

Transport layer: End-to-End message delivery. Reliable and sequential packet delivery through error recovery and flow control mechanisms. uses mechanisms like Cycle redundancy checks, windowing and acknowledgement: Eg: TCP  & UDP

Session Layer: manager user sessions and dialogues. Controls establishment and termination of logical links between users: Eg: Web browser make use of sessions layer to download various elements of a web page from a web server

Presentation layer: Encoding, decoding, compression, decompression, encryption, decryption etc happens at this layer: Eg: conversion of .wav to mp3

Application layer: Display data and images to human recognizable format. Eg: Telnet, FTP etc


Reference: http://www.inetdaemon.com/tutorials/basic_concepts/network_models/osi_model/osi_model_real_world_example.shtml


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