Aruba and Trapeze wireless switches offer tough choices

Wireless lans have real issues with security and performance, and with letting users move seamlessly across various portions of the network. Fortunately, there are wireless switches such as Aruba Wireless Networks’ Aruba 5000 and Trapeze Networks’ Trapeze Mobility System, which are capable of resolving many of the issues that have kept CTOs from approving wireless networks.

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Both products provide security that will reassure most senior IT managers, tools to fine-tune performance, and a combination of authentication and mobility features that allow users to go from office to conference room to cafeteria while continuing their mission-critical chat session.

No one could mistake one of these solutions for the other. Aruba marries security and QoS features in a system that can be fine-tuned for virtually any set of circumstances, though setting up the finely tuned system can be tedious. Trapeze features a network planning tool that does a solid (and realistic) job of planning coverage areas and generating action statements. It offers roaming between subnets that is almost invisible to users, though some security notification features

are lacking. The question for prospective purchasers is, What is my biggest wireless networking problem?

Aruba 5000

The Aruba 5000 is a modular switch that incorporates layer 2 and layer 3 switching, security, QoS, and management features in a 3U rack- mount chassis. A single Aruba 5000 can contain as many as three line cards with a total of 72 10/100 Ethernet ports and six GbE (Gigabit Ethernet) ports, up to two supervisor cards providing switching and management functions, and as many as three power supplies. All are hot-swappable.

Accompanying the switch is the Aruba 52 AP (access point), an 802.11a/b AP with twin antennas. The Aruba 52 can receive power over Ethernet directly from the Aruba 5000 or from an optional PoE (Power Over Ethernet) adapter.

Aruba’s planning tool, Aruba Site Survey, helps administrators decide how many APs to place within a given building floor and where. Portions of the tool are rudimentary. The software tends to treat floors as rectangles, and it has no easy way to take radio-absorbing or -reflecting obstacles into account. Trapeze, by contrast, has built more advanced file import and the radio characteristics of building material into its overall superior software.

Site Survey certainly has its strengths. The suggested AP placement feature includes recommended power levels, and there are functions for playing “what-if” scenarios for AP failures. In all, it’s a tool that may be useful but will not be the only planning system necessary for deployment.

The tool does not try to predict where to place the switch itself because Aruba has provided great flexibility in this respect. The Aruba 5000 can control APs connected directly to its ports or connected to its ports through intermediary switches, making it a real candidate for deployment in a network operations center.

The Aruba 5000 is also compatible with APs from other vendors. Although it will not provide the advanced control features available with the Aruba 52 AP, I found that Cisco and D-Link APs operated with the Aruba 5000 as they would with any switch, so organizations can continue to use legacy APs.

When a complete Aruba network is deployed, some APs will act as monitoring devices, providing transmitter field strength, intrusion detection, and other functions to the switch. If needed, the switch can automatically change these monitoring APs into normally functioning APs, which counters the effect of an AP dropping offline and maintains service quality, one of Aruba’s strongest points.

An administrator may assign QoS, defined as minimum allowable throughput, to individual users, user groups, or APs. If that throughput is threatened by a heavy user load, the Aruba 5000 will turn on additional APs, deny access to a particular AP from new users, and juggle AP power levels to try to maintain QoS. Watching the management screen, it was easy to see the Aruba 5000 performing all these actions as I disabled APs and brought new clients into the test scenario.