LAN/wireless LAN integration still evolving

Wireless network trends: Overlay networks all the rage in most cases

Ethernet switch vendors who offer combined or unified LAN and WLAN gear say the ultimate goal is to get wired and wireless network technologies to appear as a single network access layer. However, switch vendors and industry experts say this is still a ways off — both in terms of the technology, and the demand for unified gear from users.

Many analysts and industry observers said that corporate WLAN technology — particularly, WLAN switch technology — would be absorbed by LAN switch vendors in the long run. The thinking goes that business IT administrators would prefer wireless and management of the WLAN integrated into a wired infrastructure.

LAN/WLAN convergenceWhile LAN switch vendors who offer wireless LAN (WLAN) gear say their products are well integrated, there are still challenges in bringing together the two technologies. Some of these include:
Unified management: LAN and WLAN infrastructure may share common tools or applications for management, but these two network technologies still operate as separate entities in many enterprises, with different directories and policies.
Security: Network access control seeks to unify LAN and WLAN security and access, and technologies such as 802.1X span both realms. But access clients and protocols differ widely for users plugged into an Ethernet switch, vs. roaming laptop users.
Standards: The constant flux of the 802.11 standards has caused some to wait to deploy LAN and WLAN gear that's truly unified. The emergence of 802.11n might spur more adoption.

Vendors such as Cisco, 3Com and others have offered WLAN for more than 10 years. But this gear was based on the thick access-point model, where an access point has its own IP address and is managed as a separate network element. In 2002 and 2003, WLAN switching emerged, with a new approach to wireless. Access points are managed as network-attached radios, tied to a centralized WLAN controller or switch, which provides central access settings, configuration and security. This is what is called an overlay network: The WLAN is essentially a second network, laid on top of the base Ethernet LAN. Security, physical-layer access and management are two separate realms.

Unification on the surface

Most LAN-switch vendors with WLAN offerings sell technology bought from, or acquired by, WLAN switch start-ups. They offer WLAN- and LAN-management tools that tie together policies, device management and other tasks for wired and wireless clients, even if these users are connecting via pieces of equipment that were not developed by the same company, originally.

"Cisco has made significant progress in that area, and they're probably the leader at this point," in terms of offering unified LAN/WLAN gear with a meshed network-management layer, Farpoint's Mathias says.

Ben Gibson, director of mobility solutions marketing at Cisco, thinks WLAN technology eventually will be absorbed mostly into Ethernet-switch infrastructure. But it will take time.

"The longer-range view is that this is the direction we'll go," he says. "But there is a need for organizations to deploy WLAN controllers, either in an integrated or stand-alone fashion, depending on what they need to do."

Cisco offers WLAN controllers that can be integrated into its switches, such as stackables and Catalyst 6500 chassis. It also has WLAN controllers that run as stand-alone appliances, for the true WLAN-overlay model; Cisco acquired this technology from its acquisition of Airespace in 2004.

What Cisco has focused more on in the meantime, is bridging the network-management tools used to control security and configurations of Ethernet and 802.11-based gear. This is what users want the most.

"Not too many it organizations that can afford to double the size of their network-management staffs," he says.

Other purveyors of WLAN/LAN gear say the level of integration between the two depends on the size of the company and what problems users of the gear want to solve the most.

"When people talk about unified networks, they talk about multiple things, and that adds to the confusion," says Suresh Gopalakrishnan, vice president of Extreme's emerging products group. On one level, there is the overall appearance of a unified network. This involved setting policies for security or access that are the same for wired and wireless policies. It also involved management. Extreme, for example, offers a network-management tool that allows users to configure access settings and physical device settings for Ethernet ports and WLAN access points.

Another level of unification is having WLAN access-point controller and management features built into LAN switches. This is more popular in smaller networks, with fewer LAN switches at the edge. Or in networks that are widely standardized on one vendor's specific product.

"If the LAN edge is homogenous," Gopalakrishnan says, "then having wireless technology in the edge switch is great. You have complete control of both types of networks."

Overlay, here to stay

Most networks are not so homogeneous — even if a single LAN vendor is in place, a mix of older and newer switch models at the edge is closer to realty. This is what keeps many companies from adopting tightly integrated gear, others say.

"We don't feel or believe that unified WLAN and LAN technology has matured to the point where it can be tightly integrated successfully, without causing some degree of forklift upgrades down he road," says Bob Schiff, vice president and general manager of Foundry Networks' enterprise business unit.

"What we're seeing from customers, and expect to continue to see for at least the foreseeable future, is that customers will often choose an overlay model for the wireless," Schiff adds.

Like Extreme, Foundry has software and upgrade technology that can turn its LAN switches into WLAN access-point controllers. But customers are choosing Foundry's WLAN controller-based products — and the overlay architecture — the company offers.

The fundamental differences in WLAN and Ethernet LANs — radio waves vs. electric currents over copper — and the differences in deployment and management that stem from these differences, are the reason. Unrelated to the daily chores of maintaining a wired Ethernet LAN are site surveys, rogue access points, radio frequency and interference issues. This is why a relative degree of separation is good, Schiff says.

Scott Hilton, vice president of product management at 3Com, agrees with Foundry's Schiff that no one wants to swap out a whole LAN edge layer to do wireless. "There isn't a good business reason for it," he says. "The overlay model will be around for a long time as a result."

3Com says tightly integrated LAN/WLAN gear is more popular in its SMB segment. For this, it offers the SMB Unified Wireless Switch — a LAN switch with built-in WLAN access-point controller technology. But this box is aimed at the sub-500 user market, not the large enterprise.

Later this year, 3Com says it will expand integrated LAN/WLAN technology, with its Open Services Networking (OSN) module — a Linux-based blade, which runs in its stackable and modular switches. Hilton says 3Com is working with WLAN partners to put a WLAN controller into the OSN blade, which will run on 3Com's 5500 series of high-end stackable switches.

Standards may drive adoption

One factor that could drive more integration of WLAN technology into switching in the near future is the completion of the 802.11n standard. This IEEE standard, ratified this month, includes speeds of as high as 540Mbps, and operates on both the 2.4Ghz and 5Ghz channel spectrums.

"Until recently, enterprises were noodling with WLANs, but not really deploying widely," Farpoint's Mathias says. He calls 802.11n "the linchpin here in terms of widespread WLAN adoption," as well as deeper integration of 802.11 technology into Ethernet infrastructure.

When 802.11n is set and shipping, "there will be less worry on the part of enterprises about having to roll over their wired network to support some new [802.11] standard coming down the road."

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