Buying Tips
n Compliance
with Standards: One of the most important things to consider is to look if
the products are compliant with the specifications laid out by standards
organizations like ITU, ISO, ETSI, and ANSI. This is because the results of
using the solution have to be effective and accurate.
n Portability
and Ruggedness: This is a very important consideration, as the instruments
need to be easily accessible and should be capable of sustaining various
environmental conditions, particularly if the units are used in field.
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Test Instrument Categories |
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 Network test instruments are divided into two basic categories: Physical
Layer Analyzers and Higher Protocol Layer Analyzers. These categories are linked
to the OSI Reference Model. Higher protocol layer analyzers can perform test and
measurement across six layers of the OSI model; whereas, physical layer
analyzers focus on one layer.
Physical Layer Analyzers: On the physical layer
(OSI Layer 1), the
instruments used to measure electrical and electronic characteristics include
multimeters, cable testers, optical time domain reflectometers (OTDRs),
oscilloscopes, signal level meters, and spectrum analyzers. The most important
parameters measured by these instruments are line characteristics such as cable
length, resistance, attenuation, crosstalk, reflections caused by connectors and
terminating resistors, and electromagnetic interference from external sources.
Higher Protocol Layer Analyzers: On the higher protocol layer
(OSI Layer
2-7), processes are monitored and analyzed using protocol analyzers. These
instruments examine frames, packets, data transfer integrity, session
connections, data transformations, and application performance. There are a
variety of protocol analyzers such as universal devices with special modules for
different tasks, small hand-held devices, and software packages installed in
high-performance network node.
Application performance is measured using software agents that simulate
network use by typical applications to determine throughput and other
characteristics.
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n Scalability:
The solution has to be scalable, as it has to meet up with the evolving
technologies. The solution should allow the upgrades to happen easily through
software management. Scalability has to be in newer and deeper measurement
through software.
n Niche
Solutions: Going for general-purpose instruments, which do not address the
specific sector, could be a bad investment. This approach will allow conduct of
the tests that are necessary.
n Product
Roadmap and Support: This should be a consideration, as it will allow one to
go for a scalable solution and prevent from having an obsolescent product. As
vendors phase out products, the support would become important so that the
network would not suffer. Also, going for vendors who provide good pre-sales and
post-sales support along with the local technical and applications support can
help the solution to be finely tuned at all times. And can help one to look at a
good migratory path.
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