WLANs are already about much more than wireless connectivity. Take Symbol, creator of the first switched WLAN solution to hit the market (launched in 2002). Its big play is Total Cost of Ownership – TCO – and rightly so. It claims that its Wireless Switch System significantly lowers the cost of deploying network infrastructure by driving down the cost of managing, maintaining and upgrading wireless systems, due to its scalability and flexibility.
The solution is based around the WS5000 Wireless Switch, which centralises control and management functions for the wireless network. Intelligence that, until recently, had been designed into the access points of a WLAN, has been moved to a central switch with corresponding improvements in functionality and flexibility. The switch is based on a Linux-based RTOS, allowing new functions to be added easily, rather than requiring hardware upgrades. This centralised intelligence unifies network access, security, policy management and QoS – Quality of Service - at the switch level. It makes for easier definition of rules for QoS and security, meaning more efficient network management, as well as media independence and inbuilt scalability.
It connects via standard 100BaseT cabling and Ethernet switch or router ports to a choice of 802.11b AP100 or 802.11a/b AP200 "Access Ports" – Symbol terminology for an access point. The Access Ports contain the wireless LAN radio and antenna. Symbol claims the key benefit of this approach is a smooth, cost-effective incremental growth, since Access Ports are significantly less expensive than traditional “fat” access points. With this concept, you also gain the ability to deploy new technologies without disruption to an existing wireless LAN installation. And they can be mounted essentially anywhere. Power can be distributed to Access Ports over Ethernet cabling using Power Injectors, so no AC mains is required as there would be for each traditional access point.
From a management perspective, system management functions are available via an XML-based graphical user interface, a command line facility (using telnet, the Switch's serial port, or PPP), and Java-based browsers. Using this GUI, the Wireless Switch System can be completely controlled, regardless of the number of switches and Access Ports added. From a performance perspective, the WS 5000 supports load balancing (moving users from a congested Access Port to one with more available capacity), pre-emptive roaming and clear-channel detection for improved bandwidth utilisation, so that as you roam across different APs, performance stays constant and doesn’t degrade or dropout.
WS 5000 QoS options are extensive. Service classification and QoS management options include support for the IEEE 802.1p traffic prioritisation standard, service fairness, support for virtual LANs (VLANs, via IEEE 802.1q), the ability to provide multiple simultaneous ESSID domains (in effect providing multiple wireless LANs on a single infrastructure), layer 2/3 filtering, DHCP, NAT and Mobile IP. This amounts to a huge range of options when it comes to controlling traffic across the Wireless LAN. Similarly, where security is concerned, Symbol has a tiered-security solution, where customers can choose application level security – based on what is required and can be used. There are many options, but one size does not fit all, so Symbol gives all the standard options such as WEP (Wired Equivalent Privacy), 802.1x and WPA (dynamic WEP, supported by XP clients and others) as well as its own Keyguard encryption and Kerberos authentication options.
How well does it work?
We put the Symbol system to the test in a number of ways, from basic performance to security and mobility tests, focusing on the claimed ability of the Symbol system to maintain performance and application connections, regardless of how many times the connections to the different APs changed transparently (to the casual user) as we roamed across the network. The results were excellent – problem free with no loss of connection at any point and good, sustained performance (signal strength) levels. The ability to assign multiple ESSIDs meant we could minimise the impact of broadcast traffic on the network. This not only saved valuable bandwidth but also enabled us to significantly improve the battery life of the portable client devices we used for the testing, as they were not required to “wake” from their standby modes as often as they would otherwise be requested to do by regular broadcast traffic.
We also looked at what kind of distances we could achieve, moving further and further away from the nearest AP, the signal having to cope with 60cm thick stone walls. We got to the equivalent of the edge of a fair-sized company car park before we lost connectivity (down to 2 Mbit/s minimum setting at that point). This kind of coverage also emphasises the importance of having a proper security policy in place and here again the Symbol solution shines with a wide range of “pick ‘n’ mix options that worked very well in practice, like the switch as a whole.
Overall, we liked the flexibility offered by the Symbol system in all areas, the centralised point of management and the competitive starting price.
Companies putting a wireless LAN into an office should consider this solution. Security and roaming work well and the product has been well tested in the market.