by August 11, 2003 0 comments





Technology is no longer judged by its technical brilliance, but by the return on investment (both tangible and intangible). This, in turn, is dictated by the killer application for that technology. How does wireless networking fit into this? It fits in because the technology has been around long enough and can provide enough benefits to be seriously considered for deployment.

At the enterprise, it provides communication support for ‘on the move’ computing. It overcomes and, in fact, annihilates the physical limitation of wired networks in terms of adaptability to a variation in demand. Network connectivity in a company’s meeting room is a classic example. The number of users using that room would vary for different meetings. So, it would be difficult to decide how many wired network ports to put there. With wireless access, the number of users connecting is mostly constrained by the bandwidth available on the wireless network.

Mobility is another USP for wireless. Mobile users can be truly mobile, in that they don’t need to be bound to their seats when connecting to the network. Mobility, however, is not only associated with users. It’s also associated with the infrastructure itself. You can have a wireless network up and running in no time, a boon for people who need to do it for exhibitions, events, etc.

Intel Centrino
Intel’s Centrino technology aims to make laptops Wi-Fi enabled, thinner and lighter with longer battery life 
WIFI Technology Standards
Which Wi-Fi standard should you use? How can you handle security issues? Where is it headed?
Wep Security Cracked
Existing Wi-Fi security measures, such as WEP and RC4, can be cracked 
Bluetooth vs wi-fi
Wi-Fi is deployed on LANs while Bluetooth is suitable for Personal Area Networks

This leads us to the other USP of wireless, that of scalability. What if your company has suddenly started recruiting people like there’s no tomorrow, and you need to provide network access to all the newcomers. Your existing wired infrastructure might have some room for scalability, but what if the number of users exceeds that? Laying fresh cabling would take ages, even if you buy more floor space for them. Wireless technology can really help in extending your network. It also becomes important if an enterprise has a rented office and needs to shift to a new place. At home, the need for wireless networking is more to do with ubiquitous computing. You put an access point router that connects to the Internet and take a laptop with a wireless card, and you can then move around anywhere in the house and always be online.

IDC projects that the total wireless LAN equipment revenue in India will enjoy healthy growth at a CAGR (compound annual growth rate) of 35%, from 2002 to 2007. Another projection by Gartner Dataquest says 50% of all the laptops sold will have Wi-Fi prebuilt by 2004. These numbers are actually an indication of bullish attitude of the users and hence of the involved companies. In the Indian context, Wi-Fi is still at a nascent stage in terms of deployment, being currently used by the hospitality sector and some leading educational institutes. But given the fact that the 802.11b wireless standard has been made free from licensing for indoor use, things should pick up in other sectors as well. Wireless technology, therefore, is happening, and should be seriously considered. In this story, we’ll discuss the key considerations when going for wireless networking both at the enterprise and at home.

Wi-fi at the enterprise
The assumption that creating a wireless network is as simple as putting up a wireless-access point falls flat when it comes to deploying it in an enterprise environment. There are a lot of variables that need to be considered for successful deployment.

As wireless networks are shared, the capacity delivered should be the most important consideration while designing them.

While most SOHO deployment can do with a hit and trial method, enterprise-level deployment needs careful planning–management and security being just two of the issues. Let’s look at the issues involved in deploying Wi-Fi ats the enterprise.

First, the standards and what’s available for use. Currently, there are three wireless LAN standards available: 802.11a, 802.11b, and 802.11g. Of these, the first one works on the 5 GHz band, provides shared bandwidth of 54 Mbps, but requires a license to operate. It’s, therefore, not currently an option for enterprises. The remaining two, b and g, operate in the 2.4 GHz band, and while the former gives 11 Mbps, the latter gives 54 Mbps bandwidth. Currently, government regulations have freed the b standard for internal use, which can therefore be easily deployed. Though there are products available in the g standard, it’s still not been deregulated. The good news is that there are dual-mode products available that can support both the b and g standards. So you can first go for 802.11b equipment, and later upgrade it to g whenever it gets deregulated.

Products for both standards are widely available. One caution, though, is that backward compatibility for 802.11b also means that when an 802.11b device joins an 802.11g access point, throughput for 802.11g clients can be slow because of the longer transmission times taken by the 802.11b clients to communicate.

Before deploying a wireless network, you must conduct a preliminary site survey. Ensure there’s nothing that would interfere with your wireless connectivity. That’s because both 802.11b and g devices are susceptible to interference from other devices like 2.4 GHz cordless phones that also operate in the same 2.4 GHz frequency band. Even Bluetooth devices sitting at close proximity to 802.11b equipment can cause interference. Next, you need to consider the following key aspects: what applications are you primarily going to run on your wireless network; how much bandwidth would be required for each user; how many users will be on this network at a given time; which areas do you want to be covered by wireless.

First, determine the applications you plan to run on the wireless network and how much are they going to load it. Do you plan to do heavy data transfers over it or do you want to use it for simple things like Internet browsing? This will help you determine the approximate bandwidth that will be needed for each user. You then need to know how many users will be using it at any point of time, and the efficiency of the network. Here, the efficiency of the network is the actual throughput you get from the access point. The wireless medium is time division multiplexed, meaning a client can either send or receive data at a time, but not both. Plus, the actual transmission rate is dictated by physical factors like indoor settings and quality of equipment used, and therefore never measures up to the rated (11 Mbps for 802.11b). The maximum you would get would be 4 to 6 Mbps one way, upstream or downstream.

Bandwidth and coverage are critical elements when designing a wireless network, and both must be looked at together. Since a wireless network uses shared bandwidth, the throughput reduces as the number of clients increases. On the coverage front, 802.11b based access points can provide access up to a radius of 80 feet indoors, and the throughput decreases with distance. Some access points also have an auto stepping feature where the rate decreases with distance in steps. The whole idea therefore, is to be able to guarantee a minimum QoS (Quality of Service) to every user. In other words, the QoS needs to be defined such that a user is guaranteed a certain amount of bandwidth depending upon the application he’s using. So, for QoS, you need to decide the maximum number of users that should be able to access the wireless network at different distances. In order to maintain the QoS, the number of users that can connect must reduce as the distance from the access point increases. So, at a particular distance, the moment an extra user logs onto the network, he/she is forced to move to another access point to maintain the QoS. This won’t degrade the quality that other users are getting. This will also help you decide the number of access points you really need. Bear in mind that increasing the density of access points serving a particular area would ensure a higher
QoS.

Once you’ve determined the number of access points, you need to determine where to place them. This is possible by doing a site survey, which entails a link quality test through out the enterprise premises and placing access points appropriately while minimizing the number of “black spots”. These are areas where there’s no wireless access. Besides black spots, you must also ensure that no two adjacent channels have an overlap of the same frequency. Otherwise, there will be interference and the wireless network will not function. Both 802.11b and g can support up to 3 non-overlapping channels. For more detailed information about channels, you can refer to the wireless technology section towards the end of this section.

This covers the fundamental design considerations of a wireless network. You can also build redundancy into the network so that even if one access point fails, another one takes over. This will lead to reduced performance as the other access point will take on additional load, but at least the user will not loose the connection. Some access points even provide power on Ethernet facility in addition to a separate power supply. So if the power supply fails, they can seamlessly shift to power from the Ethernet, and users don’t loose the connection.

Once the deployment has been done it should be verified before actually activating it for production use. Managing and optimizing the wireless network comes next. Most access points have their own Web-based configuration. While this might be fine for a small wireless setup consisting of a few access points. However, as the number of access points increases, it would become difficult to manage each one individually. In that case, you may need to use a network management software. Check with your access point vendor for a central software that can manage all the access points. Also, check whether the access points themselves support SNMP, so that their basic usage statistics can at least be picked up by any standard network management software. Lastly, before doing an actual company wide Wi-Fi deployment, it’s always recommended to do a pilot rollout.

Wi-fi at SOHO
You can have a basic wireless-network setup within minutes, comprising one or two access points and a few access cards for laptops and PCs. Wireless equipment is also available for every need and pocket, making it a lucrative option for homes and small offices. Having said that, it’s important to understand the equipment suitable for homes and small offices, and what to take into account when deploying.

In a home scenario, where you probably have an Internet connection on the desktop, you can use Wi-Fi to share it with other devices such as PDAs and laptops. Wi-Fi will let you take your devices anywhere in the house and still remain connected. All you need are wireless cards for the various devices, and they can communicate in peer—to—peer mode. This setup, however, is not suitable for more than five devices and if that happens (as in the case of a small home office), you’ll need to put in an access point.

There are access points with features specifically for home and small office users. For instance, the D-Link 714P+ router has a built in 10/100Mbps switch and print server functions. It can also be setup as an Internet router, and inbound connections can be filtered. This type of a router can also be good for wireless enabling specific locations, such as presentation rooms and lounges.

Security could be an issue in a SOHO environment, as anybody in the vicinity can try to hack into your access point. This may not be very easy, as many access points, such as the one we mentioned above, have a built-in 256-bit WEP security, which would take a while to crack.

Wireless Equipment>>>>>>>>>>

D-Link DI-714P+ 2.4 GHz (802.11b) Wireless Router
Plus Print Server


Price:
Rs 11,000 
Meant for: SOHOs, schools, coffee shops
This is good for setting up a small network and sharing broadband Internet connection among multiple users, both wired and wireless. The unit has a Wireless Access Point, a High-Performance Router, a 4-Port 10/100 Ethernet switch and a print server to share the printer cable free. It also has advanced firewall capabilities to ward off Internet attackers. 
Contact
: D-Link India. E-mail: sales@dlink.co.in  

D-Link DWL-900AP+ 2.4 GHz (802.11b) Wireless Access Point
Price: Rs 8,250
Meant for: Adding wireless capability in small to medium LANs
With this access point you can build a WLAN on your existing Wired LAN instantly. It can be configured to perform in any one of five modes as a wireless access point, a point-to-point bridge with another access point, a point-to-multi-point wireless bridge, a wireless client, or a wireless repeater. Both D-Link products support 64, 128, or 256-bit WEP encryption and provide up to 22 Mb/sec speed with other D-Link Airplus Wi-Fi products.
Contact: D-Link India. E-mail: sales@dlink.co.in  
Cisco Aironet 1200 2.4 GHz (802.11b) Wireless Access Point
Price: Rs 64,728
Meant for: Large enterprises 
This combination of an access point and a wireless radio can be either 802.11a or b. It allows for dual-band configuration. This is much more expensive than the D-Link access point as it supports advanced 802.1x authentication services. It also has advanced features for enterprise standard, secure and manageable networks.
Contact: Cisco, Delhi. E-mail: canil@cisco.com
. Tel: 6233201. 
PCMCIA and PCI wireless LAN adapters
PCMCIA D-Link DWL-650+ Price: Rs 4,650  
PCMCIA Cisco Aironet 350 Price: Rs 12,168  
Wireless adapters are the end-user Wi-Fi equipments and provide wireless connectivity to individual systems. These can be connected in ad-hoc (peer-to-peer) and infrastructure (access point) mode. These adapters are available in multiple interfaces like
USB, PCI and  Compact
Flash.

 
Cisco Secure Access Control Server

Price: Rs 300,000
for version 3.1 (for windows)
Meant for: Large enterprise-level wireless LAN infrastructures
Cisco Secure Access Control Server provides centralized identity based wireless networking solution across all Cisco devices and security-management applications. It offers RADIUS features for authentication, authorization and accounting of wireless clients on a user basis. It can control who can log in to the network, assign privileges to them, provide security audit or account billing information, etc.
Contact: Cisco, Delhi. E-mail: canil@cisco.com
. Tel: 26233201. 
Other Wi-fi
Equipment


Outdoor Wi-Fi products let you create networks and provide outdoor users with wireless Internet access and are useful in areas like manufacturing plants, industrial locations, military bases, universities, college and high school campuses, hotels, airports, golf courses and marinas. They can also be used to make wireless backbone networks. For outdoor connectivity different kinds of antennas to extend the wireless range are also available. One interesting product is the wireless motion camera, which can be used as a powerful surveillance system to provide remote high quality audio and video.

 

No Comments so far

Jump into a conversation

No Comments Yet!

You can be the one to start a conversation.

Your data will be safe!Your e-mail address will not be published. Also other data will not be shared with third person.