Making the Private Network Public-Layering

 
Making the Private Network Public-Layering
If public access hot spots can be established by enabling existing and proposed enterprise WLANs to
deliver public Wi-Fi coverage, the market would be much closer to making wireless Wi-Fi availability
ubiquitous. This approach is called layering. Layering uses existing WLANs from larger enterprises to
provide the bandwidth for public networks (hot spots). Unlicensed enterprise systems often cover or spill
coverage out onto prime urban property and locations frequented by potential Wi-Fi users.
Layering for enterprise networks involves installing a network management gateway that recognizes and
differentiates between authorized users from the enterprise and public access visitors. Enterprise users
can receive secure IP Security (IPSec) encrypted WLAN service-with their communications operating
over a guaranteed bandwidth allocation securely separated from that of visitors making use of the
network. Visitors are directed to a WISP login screen and experience typical public hot spot service.
Layering provides additional revenue opportunities for WLAN implementations that can offset some of the
implementation cost issues and hurdles faced by some IT managers. Figure 8-6 illustrates the process of
layering.
Figure 8-6: Layering is the resell of corporate bandwidth to the public in nearby locations.
Security and Bandwidth Management Security concerns are addressed by the gateway that manages the
subnet of APs and assigns different roles to different groups or classes of users. One of these roles is
designated for visitors who are blocked from accessing the enterprise systems and are channeled to and
through the hot spot gateway software. The gateway can also perform wireless link encryption
(supporting IPSec and Point-to-Point Tunneling Protocol [PPTP] encrypted tunnels) and authentication
using a built-in database or links to existing Remote Authentication Dial-In User Service (RADIUS)
servers. Virtual LANs (VLANs) are used to segment the traffic between private and public use. VLANs
can also limit the bandwidth of the public use and cut back on it on an as-needed basis. This way, a
business can sell its excess bandwidth to the public in a hot spot up to a mile away from the building,
assuming it uses the right antenna technology.
The layering model vastly expands the community-based approach started by urban residential
broadband users who began offering free Internet access over their DSL connections by letting others in
their neighborhood connect through their 802.11b APs. Many existing and proposed enterprise WLAN
locations could use layering to provide hot spot coverage. Enterprise offices that front onto public spaces
and that frequently host visitors, auditors, or consultants can benefit both themselves and their tenants/
visitors by offering WLAN layering. Location owners will also benefit from the improved enterprise WLAN
implementation economics that will be realized by offsetting hot spot revenue sharing against capital and
operating costs.[