Networks

CSCI-N 100

Dept. of Computer and Information Science

The Basics

Early years networks were scarce Early PCs worked as standalone Interaction limited to one person with software Engineers anticipated networking has

advantages Bob Metcalf, 1975, Ethernet

Network Classification

PAN – personal area network

NAN – neighborhood area network

LAN – local area network

MAN – metropolitan area network

WAN – wide area network

PAN – personal area network

Personal devices Usually within 30 feet No cables or wires

Example – wireless transmission of data from computer to PDA, cell phone, printer

NAN – neighborhood are network

Limited within a geographic area

Spread over several buildings

Example - local Starbucks

LAN – local area network

Limited to a very small geographic area

Usually one building Can be wired or wireless Type of network most

likely to work with in school, business, home

Example – school computer labs, home networks

MAN – metropolitan area network

Public High speed access Voice and data

transmission Range about 50 miles

Example – ISP, cable television, local telephone

LAN Standards

Standard by the Institute of Electrical and Electronic Engineers (IEEE)

Designation number refers to standard Helps to identify compatible network

technologies Ethernet, WiFi for home, business

Connections

Node – point on a network

Network interface card (NIC) – usually circuitry built in-

- Add on slot on system board, USB port, notebook PC slot

Client/Server – Why not both

Client– The user– Ask for information– Data sent to server

Server– Responds to the user

(client)– Application server– Print server

Sends back data

Network topology

StarRingBusMeshTreeHybrid

• Two types of topologies: Physical and Logical

•Physical topology of a network refers to the layout of cables, computers and other peripherals

•network cables coming out of every computer that is part of the network, then those cables plug into a hub or

switch

•Logical topology is the method used to pass the information between the computers

•the network works with all the computers talking (think of the computers generating traffic and packets of data going everywhere on the network)

•computers will be talking to each other and the direction of the traffic is controlled by the various protocols (like Ethernet)

Star

Reduces risk of failure. Expanding the network

is simple. Managing the network is

centralized. If the hub breaks down,

the system fails.

Ring

All clients have equal access to data.

This gives even performance under heavy demand conditions.

Difficult to add another host to the ring.

Bus

Simple, cheap, reliable, efficient use of cable.

Isolating problems is hard.

One error can halt the system.

Mesh

This redundancy allows the system to continue if some connections fail.

However, multiple connections are expensive.

Tree

Point-to-point wiring for individual segments.

Supported by several hardware and software venders

Overall length of each segment is limited by the type of cabling used.

If the backbone line breaks, the entire segment goes down.

More difficult to configure and wire than other topologies

Hybrid – Star and Bus

Network expansion is simple.

If one client fails, the entire network does not fail.

If one hub fails, all connections to that hub fail, although other hubs continue to function.

Devices

Any electronic device that broadcast network data Can include

– Hubs, links 2 or more nodes of wired network– Routers, ships data from one network to another– Switches, only sends data to specified destination– Gateways, used to join 2 networks using different protocols,

different address ranges– Bridges, connects 2 similar networks without regard to network

format– Repeaters

References

Slide 11– http://www.firewall.cx/topologies.php

Slides12, 13, 14– http://www.geocities.com/richard_leigh_bowles/theory/summaries/ntf/chap1.htm

Slide 15– http://chauncy-ict.pbwiki.com/Mesh%20Topology

Slide 16– http://fcit.usf.edu/Network/chap5/chap5.htm#TreeNetwork