Have you ever been faced with the situation in which an
existing department in your government agency needs to relocate to another
building—near your existing campus? You might think that it’s not a problem—you
can just run fiber to it, since it’s so close. But wait, there is a catch. The
catch being that the building to which they are relocating is not owned by your
organization and is being leased.

You may not want to spend the funds to bring fiber to a
location that you don’t own or that may only be in use temporarily. What are your
choices—DSL or cable? It’s possible in a few cases, but for a large department
with many users, such a small pipe would not be enough. Leased line or frame
relay can work and is often the choice in these cases, but it does come with a
not so insignificant monthly fee. WLAN has its own issues, including distance
limitations, interference, and security.

So what else can we pull from the bag of tricks? How about
wireless bridging? Before you start cringing, wireless bridging has come a long
way in the last few years and can be a viable option in place of another WAN
connection.

Wireless bridging

Wireless bridging is not a new concept and has been available
for several years. However, in its first incarnations, wireless bridging was
not necessarily easy to set up and maintain, and reliability could be variable.
Because of this, many IT administrators did not consider it when planning the
infrastructure. This is unfortunate, because for every horror story, there was
probably a success story that was never heard. I implemented a 10-Mbps
microwave connection about five years ago that ran without a hiccup for several
years until it was no longer needed—long enough to pay for itself more than twice.

Needless to say, technology has advanced dramatically from the
10-Mbps days and can now reach speeds from 100 Mbps to 1.2 Gbps. Let’s take a
look at the different types and compare their features.

Optical

If you are fortunate enough to have line of sight to your new building
and the distance is less than about 1.2 miles, a laser-based solution is your
fastest option. Sporting speeds up to 1.2 Gbps and good security (it’s hard to
tap into a beam of light), these systems can be ideal for your needs. The
process in setting one up is to mount the units (one on a building attached to
your network and one at your destination building), align the beams, and go.
The drawback is inconsistency due to weather conditions or wind, which might
knock your alignment off. However, this is mitigated by auto-tracking features on
many models that help keep the beams aligned.

Microwave

Although less strict than a laser, a line of sight to your
building will again be required to employ this wireless bridge solution;
however, your reach is extended to about 25 to 35 miles. Unfortunately, while
the speeds have increased from the 10-Mbps setup that I used years ago, you
won’t be getting Gigabit speeds with microwave. If you can handle speeds in the
10- to 90-Mbps range (depending on your equipment), microwave can be an
excellent solution to deploy. Easy to set up, easy to maintain, and fairly
inexpensive (roughly $10,000 to $12,000) per installation, this setup can pay
for itself in usually a year and a half. Again, the weather can cause some inconsistency,
but usually only in extreme cases. Wind can affect the alignment, but again,
assuming it was installed correctly, it will take a pretty strong wind to
require reconfiguration.

RF (Radio Frequency)

If perfect line of sight is a problem, or you need to go a
significant distance, than RF may be the choice for you. Boasting speeds of up
to 300 Mbps to a distance of 100 miles or so, and with the ability of some
equipment to “bend” signals around obstacles, RF can be your long-haul
solution in your metropolitan network. RF is very weather resistant; however,
security can be an issue. After all, it is a broadcast radio signal, so VPN is
a requirement over this kind of connection. Lastly, RF can interfere with other
RF, so if there are a lot of other transmitters in the vicinity on the same
frequency, there can be some interference.

While none of these solutions can be called the
“perfect” solution, they may be the perfect alternative to a WAN
connection, depending on your situation. All are priced to be competitive with
what you are paying for a leased line or frame relay connection over a year or
two and give you the added bonus of moving it and using it later should the
department or organization you are supporting relocate again.

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