01 Introduction

Data Communication¶

Exchange of data b/w devices via transmission medium, where data is information presented in form agreed by involved parties. Termed from ‘telecommunication’ - communication at a distance

Components of Data Communication¶

• Message
• Sender
• Sending protocol
• Medium
• Receiver
• Receiving protocol

Node¶

Device capable of sending/receiving data to/from other notes on network

Network¶

Set of devices connected by communication links

Purpose¶

Share resourcces

• File sharing
• Hardware sharing
• Application sharing: Client/server apps
• Network graming
• User Commuication
• Voice over IP (VoIP): allows calls over traditional IP rather than by traditional PTSN

Distance-Based Classification¶

Parts of Network¶

Links between one/more routers should be a ‘dedicated link’

Transmission Modes & Media¶

Wireless can - Infrastructure-Based: Mobile Network - Infrastructure-less: Bluetooth

IDK¶

Transmission Modes¶

Line Configurations¶

Topology¶

Arrangement of nodes in a network

	Bus	Ring	Star	Mesh	Hybrid
Arrangement	Sequential	Each node connected to 2 adjacent nodes	Nodes directly connected to a central ‘controller’	Every device connected to every other device in point-point manner	Combination of star and bus
Working	Devices collectively help transfer data b/w points Terminators stop signals after reaching end of wire, to prevent signal bounce	Token-Passing (Token: Message which gives priority to a station to use ring) - Data hops from one device to another until it reaches its destination - Each device communicates its routing info to every other connected device - Each device then determines either passes/keep received data
Device Used	Tap Drop line	Repeater	Hub/Switch/Router
Advantage	Simple Cheap Easy installation Node failure does not affect others	Easier to manage Easier to locate defective node/cable problem Great for transmitting signals over long distances on a LAN Handles high-volume network traffic Enables reliable communication	- Good for modern networks - Low startup costs - Easy to manage - Easy to expand - Great availability of equipment - Scalable - High security	Highest redundancy Low failure chance Low traffic Easy fault identification Robust
Disadvantage	Not fault-tolerant Prone to congestion No security	Expensive Single point of failure Requires more cable & network equipment at start Fewer equipment options Fewer options for high-speed upgrades Only one station can send message Requires tokens Requires multiple repeaters No security	Single point of failure - If hub fails, everything fails Possible congestion at hub Requires more cables than bus	Expensive (Many cables, I/O port, connections)	Same as star
Method	Half-Duplex	Simplex	Duplex?
Example	Ethernet			Between ISP routers
Duplex/Half-Duplex links	1	0	\(n\)	\(\frac{n(n-1)}{2}\)
Simplex links	0	1	\(2n\)	\(n(n-1)\)
Diagram

Network Devices¶

Network Rules¶

Protocol¶

Consists rules for the following aspects

The Internet¶

Network of networks, consisting of

• Connected computing devices
• communication links
• Routers
• Protoctols
• Communication infrasture for distributed applications
• Communication services

Standard¶

Collection of protocols agreed by organizations, such as ITU, IEEE

For eg

• Wired LAN uses standard IEEE 802.3
• WiFi (WirelessFidelity) uses standard 802.11

Internet Standards¶

• Internet draft
• RFC (Request for Comment)

Models¶

Types of Services¶

Switching/Routing Mechanism¶

Resource Division¶

1. Frequency division
2. Time division
3. Code division

TDM¶

Time Division Multiplexing

Subnet Mask¶

This is the value to perform and operation

To get the value, just make the network bits of the IP address as 1s and host bits as 0s

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