Beta user Duke University weighs 11n implications.
Cisco joins the rush to deploy draft 802.11n gear for the enterprise with a two-radio access point; with both radios, top data rate hits 600Mbps.
Cisco Tuesday jumped into the IEEE 802.11n wireless LAN market with a two-radio access point based on the draft standard and aimed squarely at its huge enterprise customer base.
Smaller WLAN rivals such as Meru previously had announced draft 11n products. But Cisco’s introduction almost instantly legitimizes these not-officially-standard products, which will form the core of next generation WLANs.
Duke University has already deployed eight of the new Cisco Aironet 1250 access points in one campus dormitory for evaluation. About 50 students live in the building. Each access point has a gigabit Ethernet link to one of two Cisco switches, which interconnect through a router with a dedicated Cisco WLAN controller in the building.
Duke network staff have seen up to about 30 simultaneous clients attaching to the 11n WLAN, most of them using 11b/g or 11a, but some using brand new 11n interfaces for example in a USB dongle.
The 11n infrastructure could be a major step forward not just in performance but in wireless reliability and consistency, according to Kevin Miller, assistant director of communications infrastructure with Duke’s Office of Information Technology. “For a long time, we and others have viewed a wireless LAN as a secondary network,” he says. But in the past year, people have started to treat the wireless net as their primary connectivity mode. “So we are very interested in evaluating the reliability as much as the bandwidth [in 11n] that could help us realize the goal of a wireless net that is more comparable to a wired net,” Miller says. “Could that become a reality? We don’t know yet.”
A New York state college is thinking along the same lines, and is already deploying the first 11n equipment from Meru. Recent studies show intense interest in 11n among network professionals.
As part of the 11n announcement, Cisco also says it is upgrading the Wireless Service Module (WiSM), which is the WLAN blade for the Catalyst 6500. The new version of this “WLAN controller-on-a-board” will support 48Gbps, up from 40Gbps, to handle the much higher throughput from the 11n access points. The Cisco Secure Services Client 5.0 software makes it simpler to provision a security and management framework for wireless clients and has a simpler, redesigned user interface.
These are critical parts of Cisco’s effort to create a unified wired/wireless strategy, and rightly so, says analyst Craig Mathias, principal of Farpoint Group, a wireless consulting firm in Ashland, Mass. “11n isn’t going to be the battleground – it will be part of the [minimal] ‘jacks-or-better’ to get into the game,” he says. “Rather, the differentiators [among vendors] will be in the value of the different architectural approaches used (and we continue to see broad diversity here) as well as the management capabilities of each, and especially in how well vendors support unified wired/wireless configurations.”
The Aironet1250 model has two 11n radios, with chipsets that can also run as 11b/g or 11a radios to support existing WLAN clients. One radio runs in the 2.4-GHz band, the second in the 5-GHz band. Cisco executives wouldn’t say whose silicon they’re using. The 11n standard allows the use of 40-MHz channels, double the width of existing WLAN nets. If both Cisco radios use these wider channels and run at the same time, the maximum data rate for the 1250 is just under 600Mbps (270Mbps for the 2.4-GHz radio, and 300Mbps for the 5-GHz radio), according to Cisco.
Using the 20-MHz channels, the maximum rates are 130Mbps in 2.4, and 144Mbps in 5-GHz, according to Cisco’s specification sheet.
Duke’s 3-week old deployment has found that data rate and throughput, with 11n clients and 40-Mhz channels, are in keeping with Cisco’s promises. “When I connected my laptop the first time, and I saw the initial 300Mbps [data] rate, I thought there was a problem with my laptop,” says Duke’s Miller.
At present, the 2.4 band at Duke will be reserved for 11b/g clients, while 11a clients will share the 5-GHz band with new 11n clients. Miller says he expects that 11a clients will slow down performance for 11n clients if they’re both using the same radio, but Duke hasn’t yet tested that configuration to see just how it will affect throughput.
External antenna fixtures let customers select from a range of omni-directional antennas and more precise directional antenna options.
The 1250 access point has one Gigabit Ethernet port to link with a Cisco standalone WLAN controller or the WLAN blade designed for the company’s widely used Catalyst 6500 switch.
Powering up 802.11n
Powering 11n access points is emerging as a key enterprise issue, because the 11n radios are power hungry. That’s not a problem if they can plug into a nearby power outlet. But if both 11n radios are running, they need about twice the power that can be delivered over 802.1AF power-over-Ethernet systems.
Cisco has created a batch of power options for enterprise customers, to make 11n adoption as painless as possible.
If just one 11n radio is active in the 1250, an existing 802.3AF system is adequate, says Chris Kozup, senior manager for mobility solutions at Cisco. To run both radios, users either can use local AC power or a Cisco power injector that sits between the access point and the nearest switch or wireless controller.
Duke is using power injectors and deployment was easy and effective for a WLAN of this size, says Miller. “We’re evaluating our options going forward, given the much greater number of access points that would need to be powered [in a campus-wide WLAN],” he says.
By the end of 2007, Cisco will offer another option: software that lets the access point negotiate a power budget with selected Cisco switches. Each switch has a “pool” of available power that can be allocated in varying amounts to a varying number of its ports, says Ben Gibson, director of mobility solutions for the vendor. Talking to the attached 1250 access points, the switch will be able to allocate the proper power level to each port, without the need for a separate power injector.
“I like the power auto-negotiation feature,” says Paul DeBeasi, senior analyst with Burton Group, a network research and consulting company based in Midvale, Utah. “That would simplify life for many enterprises.”
The Aironet 1250 is set to ship in October, with a list price of $1,299. The upgraded WiSM blade is also scheduled to ship then, with no price changes. The auto-negotiating power feature with Cisco Catalyst switch families will be available later this year, with no price changes.
The new Aironet 1250 Series product line boasts the distinction of being the first draft 11n product to be certified by the Wi-Fi Alliance. The Cisco product was part of the WFA test bed, which is being used to test and certify interoperability of draft 11n access points and adapters. The Alliance had earlier decided that draft 2 of the IEEE standard had reached a point where any further changes would be minor, and could therefore be deployed in interoperable products.
