NETWORK FUNDAMENTALS

NETWORK FUNDAMENTALS

NETWORK FUNDAMENTALS

➲ Network Topology

➲ Network Cable

➲ OSI Model

➲ Network Hardware

Network topology

➲ Bus Topology

➲ Ring Topology

➲ Star Topology

➲ Tree Topology

➲ Mash Topology

Bus Topologie

➲ Uses a common backbone to connect all the network devices

➲ A single cable(backbone) operates as the shared communication medium for all the connected devices

➲ For example: 10Base2 10Base5

Backbone

Bus Topology

➲ Advantages computers can be detached without effect other computers its cheap only a single cable is used

➲ Disadvantages if the backbone Cable is broken, the entire network go down all the traffic is send to every station bad performance if more then 15 computers are added to the

network It is slower then other topologies Cable must be terminated

Ring Topology

➲ each Computer connects to exactly two other Computers

➲ all the communication messages travel in the same direction (clockwise, anti clockwise)

➲ each node handle every packet➲ example: Token Ring

Ring Topology

➲ Advantages no kollision in the network all stations work as repeater Large networks possible

➲ Disadvantages if one computer or cable fails the network will breakdown hard to Implement Expensive components

Star Topology

➲ one of the most common computer network topologies

➲ all computers are connected with a point to point connection to a central device

➲ examples: telephone networks, modern ethernet Networks

Central Device (Switch,Hub)

Star Topology

➲ Advantages if a cable is broken only the computer wich is connected to the

cable can no longer communicate with the network if a computer fails then the other computers are not affected easy extensible high transmission rate

➲ Disadvantages if the central device fails the whole network will brakdown Network size is limited by the number of ports on the central

device

Tree Topology

➲ central 'root' node is connected to one or more other nodes that are one level lower in the hierarchy (second level)

➲ each second level node will also have one or more other nodes connected to it

➲ the nodes are connected via a point to point link

Root nodeSecond level node

Tree Topology

➲ Advantages if a computer fails then the other computers are not affected

➲ Disadvantages if a node fails all computer wich are connected to the node are

no longer reachable If the rootnode fails the whole network is down

Mash Topology

➲ Every computer will be connected to one ore more other computers.

➲ If every computer is connected to every other computer, the network will be called “complete meshed network“

➲ Example: internet, big networksComplete mashed network

Mash Topology

➲ Advantages Is the best topology, because it is the most secured one if one computer faill the communication is still possible because

the data will be redirected

➲ Disadvantages very hard to install much cable is necessary expensive

Network Cable

➲ Thicknet (Yellow Cable)

➲ BNC (cheapernet)

➲ Twisted Pair

Thicknet (Yellow Cable)

➲ is a RG-8/U coaxial cable➲ It is used in 10Base5 networks➲ to connect a network device a mau is needed➲ the cable ends must be terminated ➲ maximum length is 500 metres➲ transmission speed is 10Mbit/s➲ maximum count of computer is 100➲ Expensive

Yellow Cable

MAUMedium Attachment unit

Thinet (cheapernet)

➲ is a RG-58 coaxial cable➲ It is used in 10Base2 networks➲ the cable ends must be terminated ➲ maximum length is 185 metres➲ transmission speed is 10Mbit/s➲ maximum count of computer is 30➲ Network devices is connected using a

t-connecter

Terminator

T-Connector

Coaxial Cable structure

Twisted Pair

➲ It is used in modern networks➲ Maximum length is 100Metre➲ Transmission speed is 10-10000Mbit/s➲ There are serveral Standards for this cable

called Categories (Cat-5,Cat-6)➲ A typical cable contains 4 pairs➲ A pair consist of 2 twisted conductors

PairPlastic Jacket

Twisted Pair

Category Used for Speed FrequnecyCat 1 Analog speech transmission - -Cat 2 Token ring,isdn 4 Mbit/s -Cat 3 Ethernet 10 Mbit/s 16MhzCat 4 Token ring 16-20Mbit/s 20MhzCat 5 Ethernet 100Mbit/s 100MhzCat 5e Ethernet 100-1000Mbit/s 100MhzCat 6 Ethernet 1000Mbit/s 250MhzCat 6a Ethernet 10000Mbit/s 500MhzCat 7 Ethernet 10000Mbit/s 600MHzCat 8 Video transmission,Ethernet ???? 1500Mhz

Standards

OSI Model

➲ Is a abbrevation of Open System Interconnection model

➲ defines a networking framework for implementing protocols in seven layers

➲ The upper layer represents software that implements network services like encryotion

➲ The lower layer implements hardware-oriented functions like routing, addressing,

OSI Model

Layer Function

U

pper

Lay

er Layer 7: Application Layer Network processLayer 6: Presentation LayerData representation and encryptionLayer 5: Session Layer controls the connections between computersLayer 4: Transport Layer End-to-end connections and reliability

Low

er la

yer Layer 3: Network Layer Path determination and logical addressing

Layer 2: Data Link Layer Physical addressingLayer 1: Physical Layer Signal transmission

Nezwork Hardware

➲ Hub

➲ Switch

Hub

➲ work on layer 1 of the OSI model➲ Do not read any of the data passing trough

them➲ Broadcast the recivied packets to all

network devices➲ 3 types of hubs

passive Hubs con only send and recieve packets

active Hubs are passive hubs wich amplify the signals

Intelligent Hubs add extra functions like monitoring to an active hub

Switch➲ do the same as hubs but have more

intelligence➲ Can read the data packets to determine the

source and destination address➲ The packets will only send to the device

which have the same destination adress as the packet

➲ 2 types pf switches Unmanaged switches: have no configuration

interface,no monitoring and are cheap Managed switches: have a configuration

interface and provide functions like monitoring ➲ Switch work on serveral Layer

Switch

Type DescriptionLayer 1 switch A simple hubLayer 2 switch Most common switchesLayer 3 switch switch with router functionalityLayer 4 switch with firewall, vpn functionalityLayer 7 switch With proxy functionality