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No part of this document may be reproduced without permission ©2001 KRONE, Inc.
Catching Up With TrueNet
TM
of the KRONE
®
TrueNet
TM
structured cabling system,
much of the cabling industry
has been involved in a game
of follow-the-leader.
Numerous papers have been
published, alternative theories of measuring throughput
performance have been advanced, and generally, the rest
of the industry has supported the notion that measuring
active performance of cabling systems is the wave of the
future.
However, KRONE must repectfully admonish our industry
peers for only getting the story half-correct. We
understand that this can happen when knowledge is
stretched into unfamiliar territories, and this paper
represents KRONEs contribution toward setting the
record straight. We will discuss the various errors and
omissions made in industry research attempts, and
demonstrate the correct methods of evaluating
throughput performance. The goal is to help the reader
understand the real value of throughput performance to
the overall operation of the LAN.
In this paper, we will reference two companion papers,
Network Troubleshooting Using TrueNet, and The

(shown in Network Troubleshooting) by KRONE shows
without question that the individual ports on active
devices perform differently, both as senders and
receivers. Think all the ports on that 24 port switch
perform exactly the same? Think again. If you have the
exact same make and model of switches in your
network, do they all have identical transmission
characteristics? Again, no. Perhaps the most telling of
all: is there any relationship between what you paid per
port and how well it performs? Unfortunately, not
really. Throughput experimentation that does not take
into account the performance characteristics of
individual transmit/receive ports can easily lead to an
incorrect conclusion. Various experimental models weve
seen have failed to include key pieces of relevant data:
for example, were each of the sample channels tested
using the exact same ports on the active devices? Were
the experiments repeated using different ports? What
were the characteristics of the senders and receivers?
We can only assume that the omission of these critical
points in the papers that we have read means that
these facts arent understood, or arent considered
relevant. Port performance is very relevant, as we will
show.
Other troubling examples seem to indicate that the
experimenters dont understand how the active systems
that they are testing even work. One demonstration in
particular supposedly shows degradation of streaming
video over poor cabling. The results claim that one lost
packet caused one frame to drop, resulting in a jerky

external noise, cabling components and installation
practices combine to produce a complex and dynamic
system. Attempting to predict the performance of a
complex system like a LAN by conducting mathematical
analysis of just one element ignores the fact that
network performance is more than just the sum of its
parts.
Finally, recent experimentation with a device called
SmartBits
TM
manufactured by Spirent Communications
has been widely reported in the trade literature. In
fact, KRONE was the first to identify this product as a
possible tool to evaluate different cabling systems.
Originally, the product was designed to test switch and
hub performance by bombarding ports with simulated
network traffic, but only over a short distancein
other words, connected by a patch cord only. It is this
ability to generate traffic and count the packets as
they arrive at the other end that seemed ideal to test
whether or not cabling systems by themselves contrib-
uted to packet loss. However, upon experimentation,
we discovered that the signal characteristics in a
SmartBits NIC is abnormally good, and as such is not
representative of a real-word device such as an off-the
shelf NIC or a switch port.
Papers now circulating in the industry claim third party
throughput verification of cabling systems using
SmartBits. These experiments were conducted by
simply connecting a 90 meter basic link or channel (with

something approximating a normal receiver, instead of
using the super-receiver in the SmartBits.
First, to normalize the SmartBits signal, the simulated
traffic should be sent through a device that actually
regenerates the signal, and sends it out again using
one of the transmitters (ports) on the device. This
takes the abnormally strong SmartBits signal and re-
creates it along more normal parameters. You can do
this either with a hub or a switch, by connecting it to
the SmartBits NIC with a short patch cord. Using a
store-and-forward device such as a switch also
ensures that if SmartBits or the short patch cord
corrupt any packets, they are discarded before being
sent out over the cabling system under test. An
A channel with this mess in it, and
still ZERO ERRORS with SmartBits!
KRONE: 800-775-KRONE www.kroneamericas.com www.truenet-system.com
No part of this document may be reproduced without permission ©2001 KRONE, Inc.
Is the use of
SmartBits
incorrect? No,
but the direct-
connection
methdology is
flawed.
incoming packet from SmartBits that doesnt pass the
switchs CRC check would be discarded before being
sent out over the cabling system; therefore, only
packets corrupted by the switchs transmitter or the
cabling system itself would be counted at the far end of

plished with the three devices mentioned previously:
1. A SmartBits SB200 chassis with MIL-7710 10/100
Base-TX cards as the packet generator.
2. A Cisco Catalyst 2900 10/100 Base-TX switch to
regenerate and normalize the signal.
3. A typical 10/100 NIC with a special driver to report
errors (we used a Digitech LAN900).
For these experiments, we tested Fast Ethernet 100
Base-TX performance, as this is the most widely
deployed technology in todays LANs. We tested two
different cabling channels using this set-up, a Cat 5e
KRONE TrueNet C5eT channel, and a channel of off-the
shelf Cat 5e components from recognized manufactur-
ers that approximates a mix and match cabling
solution. The channels will be described in more detail
later.
It is important to first establish if there is any error rate
inherent to the devices themselves, prior to testing
channel throughput. To do this, we connected the
SmartBits card directly to the Cisco switch with a short
patch cord, and then out again directly to the LAN900
card with another short patch cord. This will show us if
any of the port combinations are grossly better or worse
than others. Upon testing numerous port pairings, it was
found that the error rate was zero, in all cases. A screen
shot of the LAN900 control window is shown below.
The detail indicates that 6,482,321 frames were sent
with no (frame) errors. In all the experiments, the
maximum Ethernet frame size of 1518 bytes was used.
There did not appear to be any inherent problems with

left shows, for the best
case port combination, out
of 4,089,553 frames, there
was only one error
detected.
This corresponds to a bit
error rate of 2*10
-11
, by
the following math (this will serve as the basis for all
subsequent examples):
We first need to assume that the one frame error was
the result of just one bit error (this carries forward to all
examples). In reality, its possible that there was more
than one bit error, but the probability of this is
extremely small and the net effect of one bit error or
two bit errors (or ten, for that matter), in a frame is
exactly the samethat one frame is thrown out.
Therefore:
4,089,553 frames * 1518 bytes per frame * 8 bits/byte
= 49,663,531,632 bits.
1 bit error divided by 49,663,531,632 bits = 2*10
-11
or .000000002%
KRONE Channel with Best
Case Ports on the Switch
In the second test, we
tested the worst case port
combination and found
that the error rate

ports on the switch are
used in the measure-
ment. As the screen
shots show, the error
rate increases dramati-
cally. For the best case
channel, the error rate is 1873 bit errors out of
1,928,463 frames, or 8*10
-8
(.000006%) . The worst
case channel has a staggering 5291 errors after just
183,405 frames, a bit error rate of 2.4* 10
-6
(.00024%).
(Note the difference between the error rate in the
screen shots, and the BER rate calculated. Remem-
ber the screen shots display the frame error rate, not
the Bit Error Rate.)
Effect of Alien Crosstalk
Finally, to demonstrate the dramatic effect that
outside noise can have on a cabling system, we
devised a test to simulate very strong alien crosstalk.
Alien Crosstalk is the noise from adjacent transmitting
cables in a bundle that can be heard through the
sheath on the cable being tested. The test bed was
modified to include an identical channel directly next
to the channel being tested.
Mix and Match Channel with
Worst Case Ports on the Switch
Mix and Match Channel with

favor the TrueNet solution, we offer one of the most
troubling pieces of evidence of all. Most end-users insist
on hand-held test results from their installation contrac-
tors for new installations. We demonstrated that the
real-world performance (bit errors), of these channels
are dramatically different.
Now look at the
actual hand-held
test result screens.
Which is the TrueNet
and which is the one
with the errors?
Actually, the
TrueNet channel is
the one with the
lower reading. So
how is an end-user
to know if the
Category 5e
compliant system
they purchased has
errors? The only
way to tell the difference between meeting the
standards and delivering optimum performance is to
perform active testing on the operating network.
KRONE has recognized this situation, and developed the
TrueNet cabling system and active testing methodology
to ensure that IT managers get a true picture of what
they paid for. KRONE remains the only structured
cabling provider in the world that performs on-site