Wireless Systems Design

POE Products Cut WLAN Installation Cost

This Device Family Provides Access-Point Management And Security Without The Need For Additional Power Connections.

For those people who have installed a wireless-LAN access point in their home or office, the challenge of finding an available power outlet is very familiar. This problem is even more difficult for corporate IT departments, which are tasked with deploying multiple access points within a central location or office building. Often, such locations lack accessible power outlets. To make matters worse, the cost for installing power to each access point—on average—can cost $400 per installation. This amount is typically as much as the access-point device itself. Thankfully, a new family of cost-effective power-over-Ethernet (POE) products promises to provide a welcome alternative.

Hailing from Vernier Networks, Inc., the 6500p series POE product family promises to deliver power to access points via an Ethernet cable. This approach starkly contrasts the traditional use of a separate power line. Comprising the 6500p series family are two products: the Access Manager (AM) and Integrated System (IS). Each product is based on the draft IEEE 802.3af standard for power delivery over Ethernet. In addition, they both support Cisco's proprietary power scheme.

The AM 6500p Access Manager and IS 6500p Integrated System were built on previous versions of the same products. The company emphasizes, however, that both products had to be designed from scratch to be POE-enabled. The AM 6500p Access Manager is centrally controlled from the CS 6500 Control Server (see figure). It manages and secures WLAN access points for the enterprise system. Although the AM 6500p can expand to support up to 12 Ethernet ports, the CS 6500 can manage a few or even hundreds of access points.

For a small business system, the IS 6500p Integration System offers a less expensive solution. As a single standalone device, it combines the functionality of the AM 6500p Access Manager and CS 6500 Control Server. Like the AM 6500p, it comes with four Ethernet ports. Yet it can be scaled to accommodate up to 12.

Working together, the Access Manager and the Control Server provide a complete Layer 3 WLAN security and management system. The AM 6500p acts as a gateway device between the wireless and the wired local-area networks. It allows users to link to the network while enforcing user-authentication and network-access rights.

Three option-card spaces are available for the AM 6500p. For example, expandable connectivity is achieved via a four-port Fast Ethernet card. This card can increase the number of access points that directly connect to the AM 6500p.

Gigabit Ethernet cards also are offered. They enable connectivity to high-speed backbones or downstream switches. Lastly, an encryption-acceleration option card can be used to offload the processing of 3DES encryption from the processor. This alteration results in an immediate increase in overall system performance.

The AM 6500p and IS 6500p products can both deliver up to 15 W of power over 48-V rails. The IEEE 802.3af standard requires POE support for 48-V AC. This power is sufficient to drive 12 access points over Category 5 Ethernet data cable, which is the typical configuration used for WLAN installation. The two devices also support dual-mode combination 802.11a/b radios in up to 12 attached access points.

As an added benefit, they provide support for Cisco System's "flipped-polarity" proprietary version of POE as well as the new Aironet 1200 dual-mode APs. Cisco's approach uses reverse polarity with a −49.2-V rail. Vernier's POE-compliant products, on the other hand, compensate for this polarity disparity through software in their graphical user interfaces (GUIs).

To IT managers, POE offers better control of the constantly changing office environment. At the same time, these managers can automate the handling of network faults. The devices' centralized GUI-management interface makes this possible by providing notification of physical circuit faults. With this information, network managers can diagnose and distinguish power-related hardware faults from other problems.

Other problems that might occur include cabling or software issues, such as a crashed access point. By managing access points remotely, managers can initiate functions like power cycling for access-point hang-ups; power shutdowns for unused network portions; and rapid setups and configurations. A reduction in operational expenses can then be realized from rapid fault diagnosis. At the same time, network availability can be significantly increased.

The 6500p series products have been tested on most major POE access points. This list includes the Cisco Air AP1220B Series, Cisco Air AP350 Series, Intel Pro/Wireless WDAP5000, Intel Pro/Wireless WSAP5000, Avaya AP3/AE, 3Com 6000, 3Com 8000, and Orinoco AP-2500/AE.

Now available, the AM 6500p Access Manager (POE-enabled) retails for $4945 without the associated CS 6500 Control Server. The IS 6500p Integrated System (POE-enabled), which also is available now, sells for $8995.

Vernier Networks, Inc.
465 National Ave., Mountain View, CA 94043; (650) 237-2200, FAX: (650) 237-2201, www.verniernetworks.com.

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