Current wired Ethernet LANs operate at speeds around 100 Mbps at the access
layer, 1 Gbps at the distribution layer, and up to 10 Gbps at the core layer.
Most WLANs operate at 11 Mbps to 54 Mbps at the access layer and are not
intended to operate at the distribution or core layers. The cost of
implementing WLANs is competitive with wired LANs. So why install a system that
is at the lower end of the current bandwidth capabilities? One reason is that
in many small LAN environments, the slower speeds are adequate to support the
application and user needs. With many offices now connected to the Internet by
broadband services such as DSL or cable, WLANs can handle the bandwidth
demands. Another reason is that WLANs allow users to roam a defined area with
freedom and still remain connected. During office reconfigurations, WLANs do
not require rewiring and its associated costs. Figure
lists many of
the benefits provided by WLANs.
WLANs have numerous benefits for home
offices, small businesses, medium businesses, campus networks, and larger
corporations. The environments that are likely to benefit from a WLAN have the
following characteristics:
- Require standard Ethernet LAN speeds
- Benefit from roaming users
- Reconfigure the physical layout of the office often
- Expand rapidly
- Utilize a broadband Internet connection
- Face significant difficulties installing wired LANs
- Need connections between two or more LANs in a metropolitan area
- Require temporary offices and LANs
Figure
provides
additional examples of situations in which a WLAN would be beneficial.
WLANs do not eliminate the need for Internet Service Providers (ISPs).
Internet connectivity will still require service agreements with local exchange
carriers or ISPs for Internet access. There is a current trend for ISPs to
provide wireless Internet service. These ISPs are referred to as Wireless
Internet Service Providers (WISPs). Furthermore, WLANs do not replace the need
for traditional wired routers, switches, and servers in a typical LAN.
Even though WLANs are primarily designed as LAN devices, they can be used to
provide site-to-site connectivity at distances up to 40 km (25 miles). The use
of WLAN devices is much more cost effective than using WAN bandwidth or either
installing or leasing long fiber runs. For instance, the cost of installing a
WLAN between two buildings will incur a one-time cost of several thousand U.S.
dollars. A dedicated leased T1 link, which only provides a fraction of the
bandwidth of a WLAN, will easily cost hundreds of U.S. dollars per month or
more. Installing fiber across a distance of more than 1.6 km (1 mile) is
difficult and would cost much more than a wireless solution.