TEST AND MEASUREMENT
Advantages of Transmission Testers
Performance Testing Cabling
By Dan Payerle, Business Unit Manager, IDEAL Networks
Introduction
Dan Payerle reviews
Three types of testers are available
to installers of LAN cabling who
require testing beyond what a
verifier (wiremapper) provides:
qualifiers, transmission testers and
cable certifiers. At the top end
cable certification testers like the
LanTEK perform comprehensive,
high frequency measurements of
the electrical characteristics of a
cabling system to ensure it meets the
requirements of the TIA-568 and
ISO 11801 standards. Up until the
mid 2000’s, certifiers and verifiers
where the only options installers had
for testing LAN cabling.
Data Transmission vs
Qualification Testing
Qualification Testing
In about 2004, a new type of tester
offered cable installers an option to
document their installation when a
certifier was not needed to provide
test reports for a warranty program.
The TIA/ISO cabling standards
define the measurements, pass/fail
limits and accuracy requirements for
certifiers to test various performance
cabling categories, such as Cat5, 5e
and 6 (classes for areas using ISO
standards). These new testers did
not have defined parameters in the
standards for commercial building
cabling systems like certifiers. The
word ‘qualification’ first appeared in
a standard when the TIA-570-B was
published. The 570 is a standard for
residential cabling and the section
on testing is vague when compared
to the 568 series of standards. The
TIA-570-B reads; “Cable qualification
tests the cabling to determine that
certain network technologies (e.g.,
1000BASE-T, 100BASE-T, FireWire)
will perform on the cabling system.
Cable qualification shall be performed
using network equipment installed on
the cabling, or by use of a qualification
test instrument.” This broad statement
opened the door for new types of
testers that have capabilities exceeding
those of a verifier and do not meet the
requirements of a certifier. The rest is
left up to the manufacturer to decide
how their product will ‘qualify’ a cable.
The result is that different qualifiers
can be purchased that do not measure
or report the same parameters and can
give completely different results on the
same cabling link.
Standards
A standard provides a set of rules
allowing different companies to
manufacture products that operate
with each other or provide the
same function. Different brands of
certifiers that meet the TIA/ISO/IEC
standards will report the same results
on a cabling link when compared
side-by-side. Unless a qualifier is testing
to a standard, there is no way for the
user to compare the measurement
results of one tester to another. The
reason this alternate, yet undefined
method of testing is in the TIA-570-B
is to encourage performance testing
of residential cabling to support
high bandwidth applications without
requiring a residential installer to
purchase an expensive certifier that
meets the TIA-568/ISO-11801
requirements.
Transmission Testing
Schneider Electric
White paper
Data transmission testing has the advantage of pass/fail parameters
defined by a standard.
16 NETCOMMS europe Volume V Issue 5 2015
As an alternative, some companies
introduced a technology that is
commonplace in wide area network
(WAN) testing. Data transmission
testing, or simply transmission testing,
is a tried and true method of testing
that has the advantage of pass/fail
parameters defined by a standard;
meaning the tester is not providing a
‘trust me’ report. A ‘trust me’ report
is one where the measurements,
measurement criteria and pass/fail
limits are either unspecified or cannot
be traced back to an industry recognized
test method. Within the scope of LAN
testing, a transmission tester fits into the
category of a qualification tester because
it is providing performance testing of the
cabling but is not performing the same
measurements of a certifier. However,
to call a transmission tester a qualifier is
an understatement. Unlike LAN cable
qualifiers, transmission testers perform
specific measurements and make pass/
fail determinations in accordance with
an industry standard. The standard
used for LAN testers is the IEEE 802.3
Ethernet standard that is an umbrella
document for all the different varieties
and implementations of Ethernet.
The gigabit Ethernet standard, IEEE
802.3ab, defines the data rate, frame size
and allowable delay and loss rate for a
‘good’ Ethernet system. By referencing
the 802.3ab standard, a transmission
tester provides results that the user can
be assured represent the true capabilities
of the cabling and not what the tester
manufacturer believes to be true.
Conclusion
A transmission tester is checking more
than just the physical connection
between two points to infer that the
cable is capable of supporting error-free
transmission of data. It is establishing
a complete electrical and data link
connection to the cabling or LAN
and making pass/fail determinations
of performance by transmitting and
checking Ethernet frames. This is a
direct measur [Y[