Cisco integrates wired, wireless networks

On the heels of my mentioning last week that Cisco would soon bundle some wireless LAN features into its Catalyst Ethernet switches, the company did just that.

In announcing the Wireless LAN Services Module (WLSM) for its high-end Catalyst 6500s, Cisco formally sanctioned what many WLAN start-ups have evangelized for the past 12 to 18 months: that centralized management and provisioning of WLANs is a good thing.

To use Cisco’s WLSM, your 6500 must run a Supervisor Engine 720 (another module, or “blade,” that adds a 720G bit/sec forwarding backplane to your Catalyst switch).

The upshot? You can provision and set policies for both the wired and wireless sides of your networks at the same time, says Ann Sun, Cisco’s senior manager of wireless and mobility marketing.  She differentiates the WLSM from the company’s Wireless LAN Solutions Engine (WLSE), which has also been upgraded, in that the WLSE controls the radio-frequency aspects of the WLAN, while the WLSM basically handles the traditional networking portion.

Also, now the wireless crowd gets to make use of some of the Layer 3 goodies that the wired folks already enjoy. For instance, they can use Cisco’s multipoint Generic Routing Encapsulation implementation for roaming. Their IP addresses do not change, so they don’t have to be continually re-authenticated as they cross subnets, reducing latency.

Previously, Cisco inter-subnet latencies, including access point handoffs, were about 150 milliseconds, basically consuming the entire latency budget for VoIP. That was when Cisco wireless roaming took place at Layer 2. The company says it has cut the inter-AP handoff time to less than 50 milliseconds.

The WLSM lists for $18,000 and includes a license for up to 150 access points. You can spend another $8,000 and get an IOS license to support up to 300 access points per WLSM. If you need a Supervisor Engine 720 blade, it’s $28,000.

While Cisco markets the WLSM as eliminating the “added complexity and cost of a completely separate overlay wireless LAN,” face it: this is a pricey proposition for all but Cisco’s biggest customers.

About 30% of the installed base of Catalyst 6500s currently run the Supervisor Engine 720, according to Doug Gourlay, Cisco Catalyst 6500 product manager, meaning they are ready candidates for the WLSM.