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Lesson 2
Selecting Data-Link Layer Protocols
1-19
Wireless local area networking is becoming increasingly popular now that the
products
are less expensive and more plentiful, but it is still a technology that is
recommended
only for installations where a cabled topology is impractical. If you plan
on having
computers on your network that are frequently moved to different locations,
such as
laptops or mobile kiosks, wireless can be an excellent solution. Wireless is
also a good
alternative in locations where running cables would be impractical, such as
a lobby or
plaza where cable would clash with the décor.
Before incorporating any wireless networking technology into your network
infrastruc-
ture plan, however, it is strongly recommended that you test the proposed
technology
thoroughly in the actual locations where it will be used. Wireless
transmissions are sub-
ject to interference from a wide range of environmental factors, including
the number
and composition of walls between the transceivers, proximity to machinery
and other
electrical equipment, and even climatic conditions. The effective
transmission range of
a wireless device can vary from location to location and even from minute to
minute.
You should always be sure that the medium you propose to use for your
network be
viable in the intended location before you invest time and money in the
network infra-
structure.
Security Alert
Because of recent developments in the wireless networking standards, the
popularity of wireless LAN technologies is growing quickly. However, the
development of a
security infrastructure for these networks has not been growing quite as
fast. By definition,
any wireless transceiver that comes into the effective transmission range of
another trans-
ceiver of the same type has the potential to join that network. This creates
a serious security
hazard because unauthorized users with wireless terminals can conceivably
access network
resources from outside the organization. For more information on securing a
wireless net-
work, see Chapter 13, “Designing a Security Infrastructure.”
Selecting a Transmission Speed
Another important factor in the selection of a data-link layer protocol for
your network
infrastructure is the speed at which the network can transmit data. As with
most data-
processing technologies, Ethernet networks have gotten faster over the
years, and the
cutting edge of the technology is a trade-off between high transmission
speeds and
high equipment prices. Selecting a transmission speed for your network is a
matter of
determining your users’ current and future requirements and balancing them
against
your budget.
Ethernet offers the most flexibility in terms of transmission speed. The
original Ethernet
standard called for a 10 Mbps transmission speed. Fast Ethernet, introduced
in the mid-
1990s, increased the maximum transmission speed to 100 Mbps, and Gigabit
Ether-
net—the current state of the art—runs at 1,000 Mbps, or 1 gigabit per second
(Gbps).
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