1. Communication Links
Communication Link = Physical connection or Physical Medium
Types:
Wire Pair or Twisted Pair
Coaxial Cable
Fiber Optics
Bandwidth, Optical Fiber, Light as medium, Low noise susceptibility as compared to others
Micro Wave Transmission
Satellite Transmission
Transponder, Geosynchronous sat. 22,300 miles

3. Microwave and satellite transmission
Microwave and satellite transmission. (a) To relay microwave signals, dish-shaped antennas such as these are often located atop buildings, towers, and mountains. Microwave signals can follow a line-of-sight path only, so stations must relay this signal at regular intervals to avoid interference from the curvature of the earth. (b) In satellite transmission, a satellite acts as a relay station and can transmit data signals from one earth station to another. A signal is sent from an earth station to the relay satellite, which changes the signal frequency before transmitting it to the next earth station. Transponder

4. Mixing and Matching

5. Protocols
Set of rules for the exchange of data between a terminal and a computer or between two computer
or precommunication agreement about the form in which messages or data is to be sent and receipt acknowledged.
two devices must be able to ask each other questions (Are you ready to receive a message? Did you get my last message? Is there trouble at your end?) and to keep each other informed

6. Standard Protocol
software development can be a nightmare because different vendors use different protocols. Standards help
Communications standards exist and are constantly evolving and being updated for new communications forms
the most important protocol is the one that makes Internet universality possible called Transmission Control Protocol/ Internet Protocol (TCP/IP)

7. Network Topologies Physical Layout Node (any computer or component)
Types
Star
Hub computer
Message routed through hub computer
Ring
Unidirectional, one at a time
Bus
Possible collision, retry if collision

8. Kinds of Network WAN (wide area network)
MAN (Metropolitan area network)
Mainframe to PC connection
Terminal emulation software
Micro to mainframe
Host computer
File transfer software
Download, Upload

9. Kinds of Network LAN (local area network) Physical Medium
Twisted Pair, Co-Axial Cable, Fiber optics etc.
Wireless (using infra-red or radio waves) – Easy to install and configure but slow and of short range.
NIC (network interface card)
The card contains circuitry that handles sending, receiving, and error checking of transmitted data.

10. Networking Components
Bridge
Similar networks can be connected by a bridge, a hardware/software combination that recognizes the messages on a network and passes on those addressed to nodes in other networks
Router
A router is a special computer that directs communications traffic when several networks are connected together. If traffic is clogged on one path, the router can determine an alternative path
IP Switch
IP used as Protocol
routers are being replaced with IP switches, which are less expensive and, since no translation is needed, faster than routers

11. Networking Components
Gateway
A gateway is a collection of hardware and software resources that lets a node communicate with a computer on another dissimilar network
The main task of Gateway is Protocol conversion

12. Types of LAN Client Server Peer to Peer
Thin client: A computer that has no disk storage ability and is used basically to send input to the server for processing and then receive the output
Peer to Peer
All computers in a arrangement have equal status

13. LAN Protocols Ethernet Token Ring
the network protocol that dominates the industry
uses a high-speed network cable.
Ethernet uses a bus topology and is inexpensive and relatively simple to set up.
The transmission method used by Ethernet is know as: “carrier sense multiple access with collision detection” or CSMA/CD
Token Ring
Token needed
Token Ring Uses Ring topology

14. Work of Networking Office Automation E-mail Fax (Facsimile) Groupware
Teleconferencing
Video conferencing
EDI (electronic Data Interchange)
Electronic Fund Transfer: Instant Banking
ATM machines
Telecommuting
Online services
Weather, news, online ordering of food, clothing etc.