Wireless Technology

Introduction of wireless Link in Terminal Automation at HPCL Loni.

Hindustan Petroleum Corporation limited having one of its gas plant at Loni,

Ghaziabad, which was automated by M/S Honeywell Automation India Ltd.

In 2001-2002.

Automation in Plant is working fine over LAN connectivity suddenly one

Ethernet Cable between control room to planning room got damaged/break.

In addition to above I would like to introduce that distance between control

rooms and planning room is more than 200 meters with 50 meters hard RCC

platforms in between. And hence replacement of faulty Ethernet cable was a

big project and very typical against all HPCL and Honeywell team.

Suddenly one great idea of wireless communication clicked, while testing

the same it was found ok and lots of advantage over wired LAN/optic fibre

cable link . Then it finalized to have wireless link instead of wired link.

A local area network (LAN) is a network that connects computers and devices in

a limited geographical area such as home, school, computer laboratory, office

building, or closely positioned group of buildings. Each computer or device on the

network is a node. Current wired LANs are most likely to be based on Ethernet

technology, although new standards like ITU-T G.hn also provide a way to create

a wired LAN using existing home wires (coaxial cables, phone lines and power

lines)

Wired technologies

Twisted pair: wire is the most widely used medium for telecommunication.

Twisted-pair wires are ordinary telephone wires which consist of two

insulated copper wires twisted into pairs and are used for both voice and

data transmission. The use of two wires twisted together helps to reduce

crosstalk and electromagnetic induction. The transmission speed ranges

from 2 million bits per second to 100 million bits per second.

Coaxial cable: is widely used for cable television systems, office buildings,

and other worksites for local area networks. The cables consist of copper

or aluminum wire wrapped with insulating layer typically of a flexible

material with a high dielectric constant, all of which are surrounded by a

conductive layer. The layers of insulation help minimize interference and

distortion. Transmission speed range from 200 million to more than 500

million bits per second.

Optical fiber cable: consists of one or more filaments of glass fiber

wrapped in protective layers. It transmits light which can travel over

extended distances without signal loss. Fiber-optic cables are not affected

by electromagnetic radiation. Transmission speed may reach trillions of

bits per second. The transmission speed of fiber optics is hundreds of

times faster than for coaxial cables and thousands of times faster than for

twisted-pair wire.

Although wired LAN has great connectivity and reliability but situation may be the

different as follows;

span a distance beyond the capabilities of typical cabling,

need to provide a backup communications link in case of normal network failure without delaying of 15 – 20 days.

To link portable or temporary workstations,

To overcome situations where normal cabling is difficult or financially impractical, or

To remotely connect mobile users or networks.

To overcome these situations, favor was already given to wireless technology but

recently it was not so much reliable. Now after so many changes and revisions

and after adding new technologies its become a reliable source of networking to

think beyond the wired LAN and also having great connectivity options ( up to

1GBPS is available in market and up to 3GBPS is upcoming in market.) with

great security feature compare to wired LAN.

Wireless communication is the transfer of information over a distance without

the use of enhanced electrical conductors or "wires” The distances involved may

be short (a few meters as in television remote control) or long (thousands or

millions of kilometers for radio communications). When the context is clear, the

term is often shortened to "wireless". Wireless communication is generally

considered to be a branch of telecommunications.

Wireless NetworkThe bridge provides connectivity to the wireless network for wired machines in remote locations.

Introduction

Wireless operations permits services, such as long range communications, that

are impossible or impractical to implement with the use of wires. The term is

commonly used in the telecommunications industry to refer to

telecommunications systems (e.g. radio transmitters and receivers, remote

controls, computer networks, network terminals, etc.) which use some form of

energy (e.g. radiofrequency (RF), infrared light, laser light, visible light, acoustic

energy, etc.) to transfer information without the use of wires. Information is

transferred in this manner over both short and long distances.i.e. the various

types of unlicensed 2.4 GHz WiFi devices) is used to meet many needs. Perhaps

the most common use is to connect laptop users who travel from location to

location. Another common use is for mobile networks that connect via satellite. A

wireless transmission method is a logical choice to network a LAN segment that

must frequently change locations. The following situations justify the use of

wireless technology:

To span a distance beyond the capabilities of typical cabling,

To provide a backup communications link in case of normal network failure ,

To link portable or temporary workstations,

To overcome situations where normal cabling is difficult or financially impractical, or

To remotely connect mobile users or networks.

Applications may involve, point to point communication, point-to-multipoint communication, broadcasting, cellular networks and other.

Point to point communications is a term that is used in the

telecommunications fields which refer to communications which is accomplished

via a specific and distinct type of single point connection.

Point-to-multipoint communication is a term that is used in the

telecommunications field which refers to communication which is accomplished

via a specific and distinct type of multipoint connection, providing multiple paths

from a single location to multiple locations

Wireless Distribution System :

WDS is a system that enables the wireless interconnection of access points. It

allows a wireless network to be expanded using multiple access points without

the need for a wired backbone to link them, as is traditionally required. The

notable advantage of WDS over other solutions is that it preserves the MAC

addresses of client frames across links between access points

An access point can be either a main, relay or remote base station. A main base

station is typically connected to the wired Ethernet. A relay base station relays

data between remote base stations, wireless clients or other relay stations to

either a main or another relay base station. A remote base station accepts

connections from wireless clients and passes them on to relay or main stations.

Connections between "clients" are made using MAC addresses rather than by

specifying IP assignments.

All base stations in a Wireless Distribution System must be configured to use the

same radio channel, method of encryption (none, WEP, or WPA) and encryption

keys. They can be configured to different service set identifiers (Known as SSI).

WDS also requires that every base station be configured to forward to others in

the system.

WDS may also be referred to as repeater mode because it appears to bridge and

accept wireless clients at the same time (unlike traditional bridging). It should be

noted; however, that throughput in this method is halved for all clients connected

wirelessly.

WDS can be used to provide two modes of wireless AP-to-AP connectivity:

Wireless Bridging in which WDS APs communicate only with each other

and don't allow wireless clients or Stations (STA) to access them

Wireless Repeating in which APs communicate with each other and with

wireless STAs

Two disadvantages to using WDS are:

The maximum wireless effective throughput is halved after the first

retransmission (hop) that is made. For example, in the case of two routers

connected via WDS, and communication is made between a computer

that is plugged into router A and a laptop that is connected wirelessly

using router B's access point, the throughput is halved, because router B

has to retransmit the information during the communication of the two

sides. However, in the case of communications between a computer that

is plugged into router A and a computer that is plugged into router B, the

throughput is not halved since there is no need to retransmit the

information. ( Note: This one not covered in case of terminal Automation System or in plant operation)

Dynamically assigned and rotated encryption keys are usually not

supported in a WDS connection. This means that dynamic Wi-Fi Protected

Access (WPA) and other dynamic key assignment technology in most

cases can not be used, though WPA using pre-shared keys is possible.

This is due to the lack of standardization in this field, which may be

resolved with the upcoming 802.11s standard. As a result only static WEP

or WPA keys may be used in a WDS connection, including any STAs that

associate to a WDS repeating AP.

Recent Apple base and some other brands stations allow WDS with WPA,

though in some cases firmware updates are required. Firmware for the Renasis

SAP36g Super Access Point and most third party firmware for the Linksys

WRT54G(S)/GL support AES encryption using WPA2-PSK Mixed Mode security,

and TKIP encryption using WPA-PSK, while operating in WDS mode. However,

this mode may not be compatible with other units running stock or alternate

firmware.

Wireless Router Application Platform:

Operating System

The WRAP is capable of running many different operating systems, including

various Linux distributions, FreeBSD, NetBSD, OpenBSD, as well as proprietary

OSes. The WRAP lacks a keyboard controller (for obvious reasons), so some

OSes that rely on one for the boot process may have to be modified

Wireless Bridge:

A wireless bridge is a hardware component used to connect two or more

network segments (LANs or parts of a LAN) which are physically and logically (by

protocol) separated. It does not necessarily always need to be a hardware

device, as some operating systems (such as Windows, Linux, Mac OS X and

FreeBSD) provide software to bridge different protocols. This is seen commonly

in protocols over wireless to cable. So in a

Many wireless routers and wireless access points offer either a "bridge" mode or

a "repeater" mode, both of which perform a similar common function. The

difference being the bridge mode connects to different protocol types and the

repeater modes relays the same protocol type. Wireless routers, access points,

and bridges are available that are compliant with the IEEE802.11a, b, g and n

standards. The frequency bands for these wireless standards can be used

license-free in most countries.

Wireless bridge devices work in pairs (point-to-point), one on each side of the

"bridge". However, there can be many simultaneous "bridges" using one central

device (point to multipoint).[3]

Bridging can be via WDS (Wireless Distribution System) which creates a

transparent Level 2 wireless bridge between 2 or more points. Alternately the

bridge can be setup as an Access Point / Client relationship which requires the

wireless devices used for the bridge to be set to the same service set identifier

(SSID).

An example of a point to point bridge application connecting two commercial

buildings. An example of a combination point to point bridge and point to

multipoint application connecting multiple farm buildings.

Bridging has historically referred to propagation of data across a device without

traversing a network stack, such as TCP/IP. Wireless bridging is a colloquial

term. A more accurate description of connecting two local area networks would

be a Wireless LAN to LAN Bridge. The distinction is important. While a device

may not support bridging to a remote wireless access point to connect two LANs,

it may be desirable (and supported) that a wireless access point support true

bridging; where packets traverse from a wireless to wired network without

passing through an internal protocol stack, firewall or other network abstraction.

Two bridged networks could be treated as parts of a single subnet under Internet

Protocol (IP). A wireless client would be able to make a DHCP request from a

wired server if the wired and wireless networks were bridged. In the ISO OSI

model, a device in which packets traverse the network layer is considered a

router; a device in which packets traverse the data link layer only is considered a

bridge.

A wireless router is a device that performs the functions of a router but also

includes the functions of a wireless access point. It is commonly used to allow

access to the Internet or a computer network without the need for a cabled

connection. It can function in a wired LAN (local area network), a wireless only

LAN, or a mixed wired/wireless network. Most current wireless routers have the

following characteristics:

A wireless router is a device that performs the functions of a router but also

includes the functions of a wireless access point. It is commonly used to allow

access to the Internet or a computer network without the need for a cabled

connection. It can function in a wired LAN (local area network), a wireless only

LAN or a mixed wired/wireless network. Most current wireless routers have

thefollowing characteristics:

LAN ports, which function in the same manner as the ports of a network

switch

A WAN port, to connect to a wide area network, typically one with Internet

access. External destinations are accessed using this port. If it is not used,

many functions of the router will be bypassed.

Wireless antennae. These allow connections from other wireless devices

(NICs (network interface cards), wireless repeaters, wireless access

points, and wireless bridges, for example), usually using the Wi-Fi

standard

Security

One issue with corporate wireless networks in general, and WLANs in

particular, involves the need for security. Many early access points could

not discern whether or not a particular user had authorization to access

the network. Although this problem reflects issues that have long troubled

many types of wired networks (it has been possible in the past for

individuals to plug computers into randomly available Ethernet jacks and

get access to a local network), this did not usually pose a significant

problem, since many organizations had reasonably good physical security.

However, the fact that radio signals bleeds outside of buildings and across

property lines makes physical security largely irrelevant to Piggybackers.

There are three principal ways to secure a wireless network.

For closed networks (like home users and organizations) the most

common way is to configure access restrictions in the access points.

Those restrictions may include encryption and checks on MAC address.

Another option is to disable ESSID broadcasting, making the access point

difficult for outsiders to detect. Wireless Intrusion Prevention Systems can

be used to provide wireless LAN security in this network model.

For commercial providers, hotspots, and large organizations, the preferred

solution is often to have an open and unencrypted, but completely isolated

wireless network. The users will at first have no access to the Internet nor

to any local network resources. Commercial providers usually forward all

web traffic to a captive portal which provides for payment and/or

authorization. Another solution is to require the users to connect securely

to a privileged network using VPN.

Wireless networks are less secure than wired ones; in many offices

intruders can easily visit and hook up their own computer to the wired

network without problems, gaining access to the network, and it's also

often possible for remote intruders to gain access to the network through

backdoors like Back Orifice. One general solution may be end-to-end

encryption, with independent authentication on all resources that shouldn't

be available to the public.

Access Control at the Access Point level

One of the simplest techniques is to only allow access from known, approved

MAC addresses. However, this approach gives no security against sniffing, and

client devices can easily spoof MAC addresses, leading to the need for more

advanced security measures.

Another very simple technique is to have a secret ESSID (id/name of the wireless

network), though anyone who studies the method will be able to sniff the ESSID.

Today all (or almost all) access points incorporate Wired Equivalent Privacy

(WEP) encryption and most wireless routers are sold with WEP turned on.

However, security analysts have criticized WEP's inadequacies, and the U.S. FBI

has demonstrated the ability to break WEP protection in only three minutes using

tools available to the general public.

The Wi-Fi Protected Access (WPA and WPA2) security protocols were later

created to address these problems. If a weak password, such as a dictionary

word or short character string is used, WPA and WPA2 can be cracked. Using a

long enough random password (e.g. 14 random letters) or passphrase (e.g. 5

randomly chosen words) makes pre-shared key WPA virtually uncrackable. The

second generation of the WPA security protocol (WPA2) is based on the final

IEEE 802.11i amendment to the 802.11 standard and is eligible for FIPS 140-2

compliance. With all those encryption schemes, any client in the network that

knows the keys can read all the traffic.

Restricted access networks

Solutions include a newer system for authentication, IEEE 802.1x, that promises

to enhance security on both wired and wireless networks. Wireless access points

that incorporate technologies like these often also have routers built in, thus

becoming wireless gateways.

End-to-End encryption

One can argue that both layer 2 and layer 3 encryption methods are not good

enough for protecting valuable data like passwords and personal emails. Those

technologies add encryption only to parts of the communication path, still

allowing people to spy on the traffic if they have gained access to the wired

network somehow.

Open Access Points

Today, there is almost full wireless network coverage in many urban areas - the

infrastructure for the wireless community network (which some consider to be the

future of the internet) is already in place. One could roam around and always be

connected to Internet if the nodes were open to the public, but due to security

concerns, most nodes are encrypted and the users don't know how to disable

encryption. Many people consider it proper etiquette to leave access points open

to the public, allowing free access to Internet. Others think the default encryption

provides substantial protection at small inconvenience, against dangers of open

access that they fear may be substantial even on a home DSL router.

The density of access points can even be a problem - there are a limited number

of channels available, and they partly overlap. Each channel can handle multiple

networks, but places with many private wireless networks (for example,

apartment complexes), the limited number of Wi-Fi radio channels might cause

slowness and other problems.

According to the advocates of Open Access Points, it shouldn't involve any

significant risks to open up wireless networks for the public:

The wireless network is after all confined to a small geographical area. A

computer connected to the Internet and having improper configurations or

other security problems can be exploited by anyone from anywhere in the

world, while only clients in a small geographical range can exploit an open

wireless access point. Thus the exposure is low with an open wireless

access point, and the risks with having an open wireless network are

small. However, one should be aware that an open wireless router will

give access to the local network, often including access to file shares and

printers.

The only way to keep communication truly secure is to use end-to-end

encryption. For example, when accessing an internet bank, one would

almost always use strong encryption from the web browser and all the way

to the bank - thus it shouldn't be risky to do banking over an unencrypted

wireless network. The argument is that anyone can sniff the traffic applies

to wired networks too, where system administrators and possible crackers

have access to the links and can read the traffic. Also, anyone knowing

the keys for an encrypted wireless network can gain access to the data

being transferred over the network.

If services like file shares, access to printers etc. are available on the local

net, it is advisable to have authentication (i.e. by password) for accessing

it (one should never assume that the private network is not accessible

from the outside). Correctly set up, it should be safe to allow access to the

local network to outsiders.

With the most popular encryption algorithms today, a sniffer will usually be

able to compute the network key in a few minutes.

It is very common to pay a fixed monthly fee for the Internet connection,

and not for the traffic - thus extra traffic will not hurt.

Where Internet connections are plentiful and cheap, freeloaders will

seldom be a prominent nuisance.

On the other hand, in some countries including Germany [1], persons providing an

open access point may be made (partially) liable for any illegal activity conducted

via this access point.

Introduction to the Wireless LAN Adapters:

The Cisco Aironet Wireless LAN Client Adapters, also referred to as adapters,

are radio modules that provide transparent, wireless, data communications

between fixed, portable, or mobile devices and other wireless devices or a wired

network infrastructure. The adapters are fully compatible when used in devices

supporting Plug-and-Play (PnP) technology. Host devices can be any device

equipped with a PC Card Type II or Type III slot. These devices include:

• Desktop systems

• Portable laptops

• Notebook computers

• Personal digital assistants

• Pen based computers

• Other data collection devices

The primary function of the adapters is to transfer data packets

transparently through the wireless infrastructure. The adapters operate

similarly to a standard network product except that the cable is replaced

with a radio connection. No special wireless networking functions are

required, and all existing applications that operate over a network can

operate using the adapters.

The PC Card can also be built into peripheral devices such as printers to provide

them with a transparent wireless connection to a wired network.

This document covers three types of adapters:

• PC card client adapter (also referred to as a PC card)—A PCMCIA card radio

module that can be inserted into any device equipped with an external Type II or

Type III PC card slot. Host devices can include laptops, notebook computers,

personal digital assistants, and hand-held or portable devices.

• LM card client adapter (also referred to as an LM card)—A PCMCIA card

radio module that can be inserted into any device equipped with an internal Type

II or Type III PC card slot. Host devices usually include hand-held or portable

devices.

• PCI client adapter—a client adapter card radio module that can be inserted

into any device equipped with an empty PCI expansion slot, such as a desktop

computer.

Refer to the "Radio Antenna" section for antenna differences between these

adapters.

Terminology

Throughout this document, these terms are used:

• client adapter—Refers to all three types of adapters

• PC card, LM card, or PCI client adapter—refers only to a specific adapter

• workstation (or station)—Refers to a computing device with an installed client

adapter

• End Node—A client node that is located at the end of the Network Tree.

• Infrastructure. — The wireless infrastructure is the communications system

that combines access points, mobile nodes, and fixed nodes. Access points

within the infrastructure can be either root units, which are physically wired to the

LAN backbone, or can act as wireless repeaters. Other RF enabled devices

serve as fixed nodes or mobile client nodes.

• Parent/Child Node—Refers to the relationships between nodes in the

wireless infrastructure. The complete set of relationships is sometimes described

as a network tree. For example, the access point (at the top of the tree) would be

the parent of the end nodes. Conversely, the end nodes would be the children of

the access point.

• Power Saving Protocol (PSP) and Non-Power Saving Protocol—The Power

Saving Protocol allows computers (usually portable computers) to power up only

part of the time to conserve energy. If a client node is using the Power Saving

Protocol to communicate with the network, the access point must be aware of

this mode and implement additional features such as message store and

forward. If the client node is powered from an AC line, do not use PSP.

• Repeater— A repeater is an access point that extends the radio range of the

infrastructure. A repeater is not physically attached to the wired LAN, but

communicates through radio to another access point, which is either a root unit

or another repeater.

• Root Unit. — The root unit is an access point that is located at the top, or

starting point, of a wireless infrastructure. A root unit provides the physical

connection to the wired LAN and contains configuration information in its

association table that covers all nodes that access the wired network (backbone).

All access points directly attached to the wired LAN backbone are root units.

Parts of the Client Adapter

The client adapter is composed of three major parts: a radio, a radio antenna,

and two LEDs.

Radio

The client adapter contains a direct-sequence spread spectrum (DSSS) radio

that operates in the 2.4-GHz license-free Industrial Scientific Medical (ISM) band.

The radio transmits data over a half-duplex radio channel operating at up to 11

Mbps.

DSSS technology causes radio signals to be transmitted over a wide frequency

range, using multiple frequencies simultaneously. The benefit of this technology

is its ability to protect the data transmission from interference. For example, if a

particular frequency encounters noise, interference, or both, enough redundancy

is built into the signal on other frequencies that the client adapter usually is

successful in its transmission.

Radio Antenna

The type of antenna used depends on your client adapter:

• PC cards have an integrated, permanently attached diversity antenna. The

benefit of the diversity antenna system is improved coverage. The system works

by allowing the card to switch and sample between its two antenna ports in order

to select the optimum port for receiving data packets. As a result, the card has a

better chance of maintaining the radio frequency (RF) connection in areas of

interference. The antenna is located within the section of the card that protrudes

from the PC card slot when the card is installed.

Fig: Typical wireless Installation diagram

• LM cards are shipped without an antenna; however, an antenna can be

connected through the card's external connector. If a snap-on antenna is used, it

should be operated in diversity mode. Otherwise, the antenna mode used should

correspond to the antenna port to which the antenna is connected.

• PCI client adapters are shipped with a 2-dBi dipole antenna that attaches to

the adapter's antenna connector. However, other types of antennas can be used.

PCI adapters can be operated only through the antenna port located on the right

side of the radio module (not to be confused with the antenna connector on the

card carrier).

LEDs

The adapter has two LEDs that glow or blink to show the status of the adapter or

to convey error messages.

Radio Ranges

Because of differences in component configuration, placement, and physical

environment, every network application is a unique installation. Before installing

the system, you should perform a site survey in order to determine the optimum

utilization of networking components and to maximize range, coverage, and

network performance.

Here are some operating and environmental conditions that you need to

consider:

• Data Rates—Sensitivity and range are inversely proportional to data bit rates.

The maximum radio range is achieved at the lowest workable data rate. There is

a decrease in receiver threshold sensitivity as the radio data rate increases.

• Antenna Type and Placement—Proper antenna configuration is a critical

factor in maximizing radio range. As a general guide, range increases in

proportion to antenna height.

• Physical Environments—Clear or open areas provide better radio range than

closed or filled areas. Also, the less cluttered the work environment, the greater

the range.

• Obstructions— Avoid locating the computing device and antenna in a location

where there is a metal barrier between the sending and receiving antennas.

• Building Materials—Radio penetration is greatly influenced by the building

material used in construction. For example, drywall construction allows greater

range than concrete blocks. Metal or steel construction is a barrier to radio

signals.

Link Test

The link test tool is used to determine RF coverage. The test results help the

installer eliminate low RF signal level area that can result in loss of connection.

Data Transparency and Protocols

The Cisco Aironet Wireless LAN Adapter transports data packets transparently

as they move through the wireless infrastructure. The PC Card operates similarly

to a standard network product except that the wire is replaced with a radio

connection. No special wireless networking functions are required. All existing

applications, which operate over a network, operate using the Cisco Aironet

Wireless LAN Adapter.

Protocols Supported

The Cisco Aironet Wireless LAN Client Adapter can be used in a variety of

infrastructure configurations. Cisco Aironet access points provide connections to

Ethernet Networks. When using the Cisco Aironet standard device drivers, the

PC Card is fully compliant with the protocols and wired networks listed in Table

.

Security Features

The Cisco

Aironet Wireless LAN Client Adapter employs Direct Sequence Spread Spectrum

Technology, previously developed for military anti-jamming and low probability of

intercept radio systems.

The access point must be set to the same SSID as all other devices on the

wireless infrastructure. Units with a different SSID cannot directly communicate

with each other.

System Configurations

The Cisco Aironet Wireless LAN Client Adapter can be used in a variety of

network system configurations. Access points provide connections to your

Ethernet networks or act as repeaters increasing wireless communication range.

The maximum communication range is based on how you configure your

wireless infrastructure.

Examples of some common system configurations are shown on the pages that

follow, along with a description of each.

Table 1-1 Protocols Supported

Drivers Operating Systems

ODI MS-DOS-based driver for Novell NetWare

NDIS2 MS-DOS, Windows 3.xx

Packet MS-DOS, Windows 3.xx

Ad Hoc Wireless LAN

An ad hoc wireless LAN is the simplest wireless LAN configuration. In a wireless

LAN, using an ad hoc network operating system (such as Windows for

Workgroups), all devices equipped with the PC Card can be linked together and

communicate directly with each other

Wireless Infrastructure with Workstations Accessing a Wired LAN

A micro-cellular network can be created by placing two or more access points on

a LAN. The roaming protocols allow remote workstations to move from one

microcell domain to another. The process is seamless and transparent. The

connection to the file server or host is maintained without disruption. This

configuration is useful with portable or mobile stations, allowing them to be

directly connected to the wired network even while moving about (roaming).

When an infrastructure is configured by using multiple access points and

repeaters, a mobile station is automatically associated and re-associated to the

access point which provides the best performance. This is referred to as

seamless roaming.

Typical diagram for Wireless Infrastructure with Workstations Accessing a Wired

LAN

Comparison:

Computer networks for the home and small business can be built using either

wired or wireless technology. Wired Ethernet has been the traditional choice in

homes, but Wi-Fi wireless technologies are gaining ground fast. Both wired and

wireless can claim advantages over the other; both represent viable options for

home and other local area networks (LANs).

Below we compare wired and wireless networking in five key areas:

ease of installation

total cost

reliability

performance

security

About Wired LANs

Wired LANs use Ethernet cables and network adapters. Although two computers

can be directly wired to each other using an Ethernet crossover cable, wired

LANs generally also require central devices like hubs, switches, or routers to

accommodate more computers.

For dial-up connections to the Internet, the computer hosting the modem must

run Internet Connection Sharing or similar software to share the connection with

all other computers on the LAN. Broadband routers allow easier sharing of cable

modem or DSL Internet connections, plus they often include built-in firewall

support.

Installation

Ethernet cables must be run from each computer to another computer or to the

central device. It can be time-consuming and difficult to run cables under the floor

or through walls, especially when computers sit in different rooms. Some newer

homes are pre-wired with CAT5 cable, greatly simplifying the cabling process

and minimizing unsightly cable runs.

After hardware installation, the remaining steps in configuring either wired or

wireless LANs do not differ much. Both rely on standard Internet Protocol and

network operating system configuration options. Laptops and other portable

devices often enjoy greater mobility in wireless home network installations (at

least for as long as their batteries allow).

Cost

Ethernet cables, hubs and switches are very inexpensive. Some connection

sharing software packages, like ICS, are free; some cost a nominal fee.

Broadband routers cost more, but these are optional components of a wired LAN,

and their higher cost is offset by the benefit of easier installation and built-in

security features.

Reliability

Ethernet cables, hubs and switches are extremely reliable, mainly because

manufacturers have been continually improving Ethernet technology over several

decades. Loose cables likely remain the single most common and annoying

source of failure in a wired network. When installing a wired LAN or moving any

of the components later, be sure to carefully check the cable connections.

Broadband routers have also suffered from some reliability problems in the past.

Unlike other Ethernet gear, these products are relatively new, multi-function

devices. Broadband routers have matured over the past several years and their

reliability has improved greatly.

Performance

Wired LANs offer superior performance. A traditional Ethernet connection offer

only 10 Mbps bandwidth, but 100 Mbps Fast Ethernet technology costs little

more and is readily available. Although 100 Mbps represents a theoretical

maximum performance never really achieved in practice, Fast Ethernet should be

sufficient for home file sharing, gaming, and high-speed Internet access for many

years into the future.

Wired LANs utilizing hubs can suffer performance slowdown if computers heavily

utilize the network simultaneously. Use Ethernet switches instead of hubs to

avoid this problem; a switch costs little more than a hub.

Security

For any wired LAN connected to the Internet, firewalls are the primary security

consideration. Wired Ethernet hubs and switches do not support firewalls.

However, firewall software products like Zone Alarm can be installed on the

computers themselves. Broadband routers offer equivalent firewall capability built

into the device, configurable through its own software.