computer science - networks

networks

group of computer systems and hardware linked together

LAN

• Local Network Area

• covers a local area

• based on Ethernet - set of protocols for exchanging data

• devices can use a single Internet connection, share files with one another, print to shared printers, and be accessed and even controlled by one another

WAN

• Wide Area Network

• covers an area composed of LANs

• popular WAN is Internet

• enables a user or organization to connect with the world very easily and allows to exchange data and do business at global level

VLAN

• Virtual Local Area Network

• a logical group of workstations, servers, network devices (same as LAN)

• creates a stimulated environment

• improves performance

• tightens security

• eases administration

SAN

• Storage Area Network

• secures high-speed data transfer network

• accessible to multiple servers

• appear as attached drives

• introduces networking flexibility that enables one server, or many heterogeneous servers across multiple data centers, to share a common storage utility

WLAN

• Wireless Local Area Network

• wireless method of distributing data between devices

• allows users to move around

• often called Wi-Fi network (can include other)

• increases productivity and provide convenience

Internet

• globally connected network system

Extranet

• controlled private network

• a private part of a website

VPN

• Virtual Private Network

• allows establishment of an encrypted remote connection between two computers or networks

PAN

• Personal Area Network

• covers a very small area

• examples: Bluetooth, USB

P2P

• Peer-to-Peer

• network model in which exchange of files happens

OSI model for communication over networks

» Open Systems Interconnection (theoretical)

• physical layer - transmitting and receiving raw bitstream over a physical medium

• data link layer - reliable transfer of data on a network (responsible for errors)

• network layer - routing data between networks

• transport layer - communication between applications on different hosts

• session layer - manages the dialogue between applications

• application layer - provides application services to users

transmission media

» UTP (Unshielded Twisted Pair)

• secure

• quite reliable

• low cost per meter

• speed: 100Mbps - 1Gbps

» fiber-optic

• very secure

• not reliable

• costly per meter

• speed: 5-100G

» radio waves

• very unsecure

• quite reliable

• free

• speed: 5-200Mbps

wireless networks

» Wi-Fi (Wireless Fidelity)

• used in laptops

• slow data transmission

• backwards compatible

• small transmitting radius

» WiMAX

• large distance

• high speed internet access

• cheap

» 3G (Third Generation)

• fast

• primary way for mobile phones