NETWORK DEVICES

• Gain a knowledge about network devices.

• Discuss what network devices are required to create a basic

network

• Draw a bespoke network drawing using Visio

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AIMS

• In order to setup a network a variety of devices are required.

• The network devices differ according to what network you intend to

setup.

• A network segment is a portion of a computer network where every

device communicates using the same physical layer.

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NETWORK DEVICES

• A simple network can be created between two computers (peer to

peer).

• In order to create this connection each computer must have an NIC network

interface card.

• A Network card, Network Adapter, LAN Adapter or NIC (network interface

card) is a piece of computer hardware designed to allow computers to

communicate over a computer network.

BASIC NETWORK

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NETWORK DEVICES

In terms of hardware, and excluding connection media, the most common network devices are:

• Servers

• A number of different types of server could be placed on a network.

These might include:

• Mail server for processing email (electronic mail) requests.

• Web server for processing HTTP (Hypertext Transfer Protocol) requests for HTML(Hypertext Markup

Language) files and associated assets (images, video, sound etc.).

• File server for managing access to shared network drives and folders.

• Print server for managing print queues to network printing facilities.

LAYOUT

• Application server for providing applications that can be shared with

client workstations; they may even split some of the processing

responsibility (especially for thin clients).

• Proxy server for providing an intermediary link between (typically)

the internet and client workstations on the network. For a web proxy

server, it may be that a client’s request is served from a cached copy

on the proxy rather than downloading duplicated material again from

the internet.

• Workstations – these are simple client computer systems connected to

the network, these could be:

a) Thick client – a traditional workstation that has installed applications

and is responsible for processing all of its own data. The only

significant network communication may be generated by login

authentication, remote file storage requests, email and accessing

shared resources such as printers and internet access.

b) Thin client – a newer style workstation, which may be diskless, boot

via the network and typically run applications from a centralised

application server. Sometimes referred to as a Network Computer

(NC) or Net PC. Citrix Presentation Server is a good example of a

thin client system.

THICK CLIENT

+ User experience is usually richer.

+ Less stress on servers (so less expensive servers required).

– Difficult to standardise NOS application software across all workstations.

– Expensive as processing achieved by local resources so these costs are

duplicated to each workstation.

THIN CLIENT

+ Easy to secure, fewer configurable boot options means less trouble.

+ Easy to maintain as can be server-controlled.

+ Inexpensive as processing power is required at server end (i.e. not on every

client) only.

– Reliant on good and robust network to achieve processing.

DEVICES

• Interconnection devices such as bridges, hubs, switches and routers.

• Network interface cards (NICs), which could use standard wired media, fibre optic or

wireless transmission (e.g. Wi-fi or Bluetooth).

• Vendor specific hardware (e.g. network monitor box).

• Many network specialist organisations such as Cisco, 3Com and D-Link may manufacture

proprietary network-aware devices for monitoring or controlling hardware functions.

• An example of such specialised equipment is the Mutiny appliance server.

• When the Mutiny server is connected to a network, it can perform networking mapping

and diagnostic functions on each network node it discovers (through SNMP polling).

• There are a variety

of different network devices that are

available, each of which has a specific role

within the network.

• Switch

• Hub

• Router

• Bridge

• Gateway

• Repeaters

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OTHER NETWORK DEVICES

• Switch

• Hub

• Router

• Bridge

• Gateway

• Repeaters

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OTHER NETWORK DEVICES

Investigate the following.

Provide a example where

one of these devices would

be used, If more than one

device could be used suggest

why the one you have chosen

is more suitable.

TYPES OF SWITCHES

• An unmanaged switch works right out of the box. It's not designed to be

configured, so you don't have to worry about installing or setting it up

correctly. Unmanaged switches have less network capacity than managed

switches. You'll usually find unmanaged switches in home networking

equipment.

• A managed network switch is configurable, offering greater flexibility and

capacity than an unmanaged switch. You can monitor and adjust a managed

switch locally or remotely, to give you greater network control.

• A network switch connects

network segments.

• A switch is intelligent,

it can recognise what cable

has been inserted into it and adapt to allow the network to communicate.

• It maintains a table of destination address and its port.

• When the switch receives a packet:

• It reads the destination address from the header information in the packet

• Establishes a temporary connection between the source and destination ports

• Sends the packet on its way, and then terminates the connection.

MANAGED SWITCH

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• A network hub is a device for

connecting multiple devices together,

making them act as a single network

segment.

• When a hub receives a packet at

one of its ports from a PC on the

network, it transmits (repeats) the

packet to ALL of its ports

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HUBS

• A bridge is a device that connects two networks so that they act as if

they’re one network.

• A key feature of a bridge is to enable a large network to be

partition into two smaller, more efficient networks.

• A bridge directs frames according to hardware assigned MAC

addresses while a router makes its decisions according to assigned

IP Addresses.

• Bridges work best in networks that are highly segregated.

• A bridge directs frames based on hardware assigned MAC

addresses while a router uses IP Addresses. 15

BRIDGE

• A gateway converts protocols between different

communications networks.

• A gateway can accept a packet formatted

for one protocol (e.g. AppleTalk) and convert it to a

packet formatted for another protocol

(e.g. TCP/IP) before forwarding it.

• A gateway can be implemented in hardware, software or

both, but they are usually implemented by software

installed within

a router.

GATEWAY

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• Asymmetric Digital Subscriber Line (ADSL) is a form of DSL.

• A data communications technology that enables faster data transmission over

copper telephone lines than a conventional voice band modem can provide.

• Utilizing frequencies that are not used by a voice telephone call.

• A splitter - or micro filter - allows a single telephone connection to be used for

both ADSL service and voice calls at the same time.

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ASDL

• DSL or xDSL, is a family of technologies that provide digital

data transmission over the wires of a local telephone network.

• DSL originally stood for digital subscriber loop, although in

recent years, the term digital subscriber line has been widely

adopted as a more marketing-friendly term for ADSL.

• DSL uses high frequency, while regular telephone uses low

frequency on the same telephone line.

• DSL is the most popular version of consumer-ready DSL.

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DSL

• Bandwidth is the amount of data that can be transmitted within a fixed time

period.

• Bandwidth is measured in bits per second and is usually denoted by the

following:

•bps - bits per second

•Kbps - kilobits per second

•Mbps - megabits per second

• Latency is the amount of time it takes data to travel from source to destination.

• Data is transmitted in one of three modes:

• Simplex (Unidirectional transmission) is a single, one-way transmission.

• Half-duplex allows data to flow in one direction at a time.

• Full-duplex allows data to flow in both directions at the same time. 19

BANDWIDTH AND LATENCY

• Gained knowledge about network devices

• Discuss what network devices are required to setup a network

• Create a bespoke network diagram in Visio

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CONCLUSION