Tài liệu KRONE - White paper - TrueNet - Network Troubleshooting - 2001 pptx

KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
that the answer to
network perform-
ance problems lies
in top-down solu-
tions: management
software, more equipment, faster transmission speeds.
KRONE
®
Incorporated suggests that you first look at the
foundation of your network — the structured cabling
system — and work your way up. In fact, research
conducted in KRONE’s laboratories, and hundreds of
corporate site surveys conducted by KRONE technicians,
indicate that the physical layer can be a significant
source of difficult-to-diagnose network problems.
Field tests of corporate networks while they are running
have repeatedly verified that network signals can be
compromised by both poor cabling and out-of-specification
active hardware. The result: corrupted Ethernet signals,
resulting in dropped frames, and poor application
performance. The KRONE technical papers: “The Effect
of Errors on TCP Application Performance” and “Catching
up with TrueNet” detail what happens to networks, and
Transmission Control Protocol (TCP) performance in particular,
when errors are present in a network. To summarize these
in-depth papers: no matter how well your network is
designed, or how much bandwidth you have, an error

is an error to TCP — and errors slow down applications.
The extent to which your physical network is a cause of
errors has a tremendous amount of impact on how well
your network is capable of operating. KRONE has found
that many corporate users have error-causing problems
hidden within their infrastructure, and they don’t even
know it. KRONE has developed the TrueNet Structured
Cabling System as a solution to this problem.
The TrueNet System
KRONE’s TrueNet Structured Cabling System is a complete
physical layer consisting of cabling and connectivity
components such as jacks, patch panels, termination
blocks, horizontal cable and patch cords. The system was
designed and manufactured specifically to ensure optimum
LAN transmission performance. Further, KRONE is the first
and only structured connectivity manufacturer to ensure
physical layer performance in the active domain through
our exclusive post-installation active testing program.
The inherent advantages of
post-installation active testing
We are often asked why KRONE places so much emphasis
on the active testing aspect of the TrueNet solution. There
are a number of answers, some obvious, and some less so.
A quality check of the cabling system — This might
seem intuitive, but the quality check is not for the
products themselves, it’s for the way they’re installed.
This takes on two forms: the way the product is installed
in your particular office space, with its own idiosyncrasies,
and how well our certified installers performed the job.
Your unique office environment — KRONE could

claim that we do active testing in the factory or the lab to
ensure “data throughput,” but what relationship does our
laboratory have to your office environment? The fact is,
the myriad conditions that can be present in real facilities
just can’t be duplicated in the lab. What better test of
how well it will work than testing what you actually have?
The KRONE Certified Installer’s responsibility —
KRONE Certified Installers are vigorously screened and
trained to be the best in the industry. We demand more
from our installers than any other company — KRONE
doesn’t certify a TrueNet warranty until we’re satisfied the
job was done correctly. We require our installers to send us
passive test results for every node of your installation, and we
check it to make sure it all passed. We give our installers
more than twenty additional installation requirements over
and above the standards — installation requirements that
ensure that data throughput won’t be compromised by
excessive noise, over-tightened cable fasteners, incorrect
punch-downs and so forth.
MANY PEOPLE
BBEELLIIEEVVEE
Network Troubleshooting
Using TrueNet
™
Test Methodologies
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission ©2001 KRONE
®
Incorporated
Given that office environments vary, and installation

practices have a definite effect on the performance of
the cabling system, the active test process serves as a
final check that the installation was done properly, and
the office itself doesn’t present any throughput-degrading
challenges (such as external RF noise).
A check of how your network actually runs —
Another obvious benefit of KRONE
®
active testing is
that it’s an actual test of how well the as-configured
network actually works. Since we wait until all the active
components are installed before we do our testing, we
have the opportunity to evaluate real traffic on your actual
network. Traffic generators such as Smartbits
™
can simulate
network activity and give us some information on the
cabling system, but KRONE does not typically use traffic
generators for the warranty verification for a couple of
reasons. First, for reasons explained in “Catching up with
TrueNet
™
,” devices such as Smartbits are not a good
indicator of how the real network will perform, and second,
a traffic generator has its own network interface cards
(NICs), so it isn’t really your network we would be testing.
See what the active equipment is doing —
As you’ll see later, active equipment has a variety of
transmission characteristics that can be faulty in almost
any NIC or port. Finding these faults is an added benefit

of the active testing, and often the one that our customers
find the most useful. Consider: a company moving
offices from location A to B is almost certain to buy a
new cabling system, but it’s very likely they will move all
the computers, servers, hubs and switches with them. If
any of those “imported” pieces of equipment have poor
transmitters in them — you’ve just imported a problem
into your brand new cabling system! The beauty of the
KRONE warranty test methodology is that we can find
these problems for the customer in the normal course of
performing the warranty check. It’s essentially getting a
“health check” on your active hardware for free.
Making sure you got what you paid for — The
suggestion that “any” Category 5e or 6 cabling system
will perform flawlessly in the active domain so long as it
meets the standards is simply not correct. In the “Catching
up with TrueNet” paper, KRONE shows two Category 5e
cabling systems, one TrueNet, the other “mix-and-match”
that have radically different error rates. In fact, the ”mix-
and-match“ solution dropped as many as 148 frames per
second, compared with the KRONE solution, which only
dropped one frame in 12 minutes.
What does KRONE’s bit error warranty entail —
The bit error aspect of the KRONE warranty has been
the subject of many questions, so we’d like to clarify a
point or two. The nature of the warranty is to ensure
that the cabling system will not cause bit errors that
degrade performance; provided the active hardware in
use is operating within the specifications defined by IEEE
802.3xx. The operative terms here are “cabling system”

and “degrade performance.” As shown in the KRONE
white paper “Catching Up With TrueNet,” a TrueNet
Category 5e system performs dramatically different from
the alternative Category 5e system tested. In that case,
the TrueNet Cabling System only clocked one bit error in
nearly 12 minutes — and that error could have been due
to the switch or the NIC! The alternative cabling system
had four errors per second or worse, using the exact
same port and NIC. The critical thing to understand
here is the time factor. KRONE samples actual traffic
on the network and pinpoints possible problems with
the active testing program. In doing so, we ensure that
operating bit error rates in the installed system are 10
-10
(0.000000001%) or better. As a function of elapsed
time, this error rate is so low that the effect on TCP (and
applications, by extension) is imperceptible to the user.
TrueNet System active testing
Let’s take a look at some of the real-world networks
that KRONE has encountered in site surveys. First,
however, it’s instructive to see what a well-matched
system should look like. In Figure 1, we see an
“impedance over distance” trace, which basically
shows the electrical signature of the cabling channel
over its distance. The meter scale along the X-axis
shows us this channel is approximately 81 meters long.
The electrical trace is smooth and all pairs line up on
top of each other. This is a good channel. Figure 2
shows the same channel in the frequency (MegaHertz)
domain. This could never be a precisely smooth trace,

but the lines should be as compact as possible, without
any evidence of cyclical oscillation. Figures 1 and 2
are a TrueNet cabling channel.
Now, we’ll also look at some characteristics of an active
Ethernet signal that also have a bearing on how well
signals are transmitted. They are the parameters that
define the shape of the transmitted signal, and include
rise time/fall time, amplitude and jitter.
2
An obvious benefit of
KRONE active testing
is that it’s an actual
test of how well the
as-configured network
actually works.
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
TrueNet
™
System characteristics
Figure 1 shows the impedance of a TrueNet structured
cabling channel over the distance of the entire channel
length. All the components in the channel: patch cords,
jacks, patch panels, interconnect, cross-connect, horizontal
cable and so forth, appear on this trace, but it is nearly
impossible to tell where the individual components are
located. All four cable pairs are impedance matched
throughout the length of the channel.

In the same channel, impedance is charted against
frequency (in MegaHertz) to show that the impedance
holds a tight band at 100
±
15 ohms for the critical
frequency range of 1–125 MHz where the energy of
Ethernet signals is concentrated (Figure 2).
Beyond the channel’s impedance characteristics, however, the
following active test characteristics are important to proper
network operation: network load, jitter, rise/fall time, minimum
voltage/amplitude, interference, CRC errors, alignment
fragments, interframe gap and oversized/undersized packets.
Within this document, we’ll examine three active test
characteristics: rise/fall time, amplitude and jitter.
Rise and fall time — These characteristics are important
to system performance, as synchronization requires “change
of state” to occur within a specified time frame. Even if
the signal reaches proper amplitude — but too slowly —
the signal is misinterpreted (Figure 3).
For example, TrueNet Warranty Certification Tests run at
a large, nationwide law firm showed that some sections
of their newly-installed network were running slowly. The
problem: the 100BASE-T port on a brand new switch was
out of compliance for both rise time and fall time (Figures
4 and 5). Imagine if this had been the connection to a server!
3
Nanoseconds
Voltage
Rise Time Fall Time
Rise and fall time is the length of time, in nanoseconds,

that it takes for a signal to rise or fall from one state to
another, signaling a “one.”
Figure 3: Rise and fall time.
7.8
6.0
4.3
2.5
0.8
Volts
IEEE LIMIT
Time (Nanoseconds)
GOOD
WARNING
ERROR
Figure 4: Rise time.
0 9 18 27 36 45 54 63 72 81 90
Distance (Meters)
40
50
60
70
80
90
100
110
120
130
140
Impedance (Ohms)
KRONE IMPEDANCE MATCHED CHANNEL

——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 1: A TrueNet matched impedance channel.
0 26 52 78 104 130 156 182 208 234 260
Frequency (MHz)
40
50
60
70
80
90
100
110
120
130
140
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——

PAIR 3 ——
——
PAIR 4
Figure 2: Frequency trace of a TrueNet channel.
7.8
6.0
4.3
2.5
0.8
IEEE LIMIT
Time (Nanoseconds)
GOOD
WARNING
ERROR
Volts
Figure 5: Fall time.
Rise and fall
time is the
length of time,
in nanoseconds,
that it takes for
a signal to rise
or fall from one
state to another,
signaling a “one.”
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
Amplitude — The amplitude of a wave (Figure 6) is

equivalent to the height of the physical wavelength —
also signaling to the active device a “change in state”
corresponding to a one or zero. If the amplitude is not
within the specified range, errors can occur. Using actual
test data, we “see” an active device that is well within
the specified limits (Figure 7, yellow lines). The NIC is
barely within compliance, however, and over time may
drift out of specification (Figure 8).
Jitter — In yet another installation, the 10BASE-T card
shows significant instability in meeting the IEEE jitter
specification (Figure 9). Over time, this card may begin
to emit signals not within specifications.
How are system errors found?
The previous information gives some idea of the type of
errors that the TrueNet
™
warranty testing brings to light,
but how are these errors actually found?
First, the entire network must be polled for errors. There
are various products that poll SNMP (Simple Network
Management Protocol) reports for errors. Alternatively,
specific nodes that are known to be problems can
be polled directly. By attaching a diagnostic device to
problem nodes, KRONE
®
technicians are able to capture
specific error events and filter them by type. Experience
shows that certain errors tend to be attributable to
cabling problems, and others to poorly performing
active equipment. Of course, once error events are

detected on a specific node, it is relatively simple to
determine the health of the active devices. If the active
devices check out, then it is time to analyze the cabling
traces for problems.
Figure 10 shows a series of errors. In this particular
test situation, we are seeing a number of fragment
errors, depicted on the report as “Jams” or “Runt”
packets. These packets are not complete and cannot
be interpreted by the receiving end. At the extreme
bottom of the chart, we see two errors that indicate
a wrong value in the destination prefix. This means
that the “addressee” is not known. Again, the packet
cannot be used if it’s not known where to send it.
4
Amplitude signals
a “change in state”
to the active device.
Jitter relates to the
stability of the NIC.
Amplitude
Wavelength
Figure 6: Sine wave amplitude.
10.0
7.5
5.0
2.5
0.0
Time (Nanoseconds)
GOOD
WARNING

ERROR
Volts
Figure 7: This active device from an actual installation shows
amplitude well within the specified limits (yellow lines).
4
3
2
1
0
Time (Nanoseconds)
GOOD
WARNING
ERROR
Volts
Figure 8: This NIC is barely within compliance, and overtime may
drift out of specification.
22
11
0
-11
-22
Volts
Time (Nanoseconds)
GOOD
WARNING
ERROR
Figure 9: Significant instability in meeting the IEEE jitter is
apparent in this 10BASE-T card.
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE

®
Incorporated
The exclusive TrueNet
™
test methodology extends to the
active devices in use, evaluating if NICs, hubs and switches
are performing within IEEE specifications. The end result is
a LAN that is proven to transmit data efficiently, allowing
network managers to concentrate on other concerns.
NIC concerns
In site after site, we have noticed a tremendous variation
in the performance of NICs. The rule of thumb we’ve
found is: once a NIC becomes marginal, it never gets any
better. And some NICs are marginal right out of the box —
in fact, to some users it has become commonplace to view
the NIC as an expendible resource. Some companies are
even known to keep dozens of “cheap” NICs around,
replacing them constantly, at the first sign of trouble.
We also have found that the probability of finding a marginal
NIC has nothing to do with the brand or expense of the card.
Inexpensive and expensive brands alike are just as likely to
fail; and a weak NIC (Figures 11, 12 and 13) has very little
chance of successful transmission when the poorly transmitted
5
8.0
6.5
5.0
3.5
2.0
Time (Nanoseconds)

GOOD
WARNING
ERROR
Volts
Figure 11: Rise time of a weak NIC.
8.0
6.5
5.0
3.5
2.0
Time (Nanoseconds)
GOOD
WARNING
ERROR
Volts
Figure 12: Fall time of a weak NIC.
Figure 10: This screen shot shows a series of errors, depicted in the “Failure Type” column.
22
11
0
-11
-22
Volts
Time (Nanoseconds)
BORDER LINE JITTER
GOOD
WARNING
ERROR
Figure 13: Jitter characteristics of a weak NIC.
A weak NIC has

very little chance
of successful
transmission
when the signal
must also
navigate system
mismatches.
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
signal reaches the closet (and must then navigate the usual
system mismatches in its weakened/attenuated state). This
is why we so often see 10/100 nodes auto-negotiate down
to 10 Mb/s (because they cannot maintain the transmission
at 100 Mb/s). Misguided MIS managers often attempt to
turn off auto-negotiation to prevent this from occurring,
the consequence being a virtual meltdown of the network
— nothing can get through at all.
TruePatch
™
Patch Cords test results
TruePatch Cords are a key component to the TrueNet
™
Structured Cabling System. They provide a vital system
upgrade and solve a problem found in many networks —
unmatched, low performance/low reliability patch cords.
Research has shown that even one marginal patch cord
can substantially slow down an entire network. But the
overall performance of the network can be significantly

improved just by replacing the existing patch cords with
TruePatch Patch Cords. Figures 14, 15, 16 and 17 serve
as examples of how TruePatch Cords can advance the
performance of a network. These examples are not
laboratory created simulations of theoretical problems,
they are based on real, active domain tests conducted
at various corporate sites.
An electronic components manufacturer —
Tests showed that this manufacturer has good horizontal
cable, but a poorly matched patch cord which has a much
lower impedance than the horizontal cable (Figure 14). For
such a seemingly minor part of the entire channel, that
patch cord can cause big problems for data transmission.
Notice how the patch cord causes the impedance versus
frequency chart to drop out on the low end of impedance
(Figure 15). A TruePatch cord added to the channel is
almost a perfect match (note the green pair still spikes in
the jack — Figure 16). In this case, a TruePatch cord with
the existing horizontal cabling yields a good trace for
impedance versus frequency. A TruePatch cord makes
the difference between passing and failing (Figure 17).
A top US airline — This channel was one of the worst
we had ever seen. The user on this node complained
that his computer was excruciatingly slow when down-
loading files off the network. We suspected an enormous
impedance mismatch and a wide difference in the
impedance between pairs to be the culprit (Figure 18).
The next chart shows this channel to be way out of
6
036912151821242730

40
50
60
70
80
90
100
110
120
130
140
Distance (Meters)
IMPEDANCE USING A TRUEPATCH PATCH CORD
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 16: A TruePatch cord added to the channel corrects the problem.
0 26 52 78 104 130 156 182 208 234 260
40
50
60
70
80

90
100
110
120
130
140
Frequency (MHz)
10BASE-T
100BASE-T
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 17: The addition of a TruePatch cord can be the difference
between meeting or failing the spec.
For such a seemingly
minor part of the
entire channel, a bad
patch cord can cause
big problems for data
transmission.
0 26 52 78 104 130 156 182 208 234 260
40
50

60
70
80
90
100
110
120
130
140
Impedance (Ohms)
Frequency (MHz)
10BASE-T
100BASE-T
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 15: Patch cord causes big problems for data transmission.
0 4 8 12 16 20 24 28 32 36 40
40
50
60
70
80
90

100
110
120
130
140
Impedance (Ohms)
Distance (Meters)
IMPEDANCE MISMATCH OF THE PATCH CORD, THE BLOCK AND THE CABLE
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 14: Good horizontal cable with a poorly matched patch cord.
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
specification. It took this user eight minutes to download
a large PowerPoint
®
file over this node (Figure 19). Simply
replacing the patch cord at the computer cleans up the
channel quite a bit; but will it bring the frequency chart into
compliance (Figure 20)? As you can see, the frequency curve
isn’t completely normal, but the patch cord made a big

difference nonetheless. The same file that took eight minutes
to download, now took only two minutes. Of course, actual
results on other networks will vary, but this is a compelling
example of the value of good infrastructure (Figure 21).
A software and engineering firm — Sometimes the
TruePatch
™
Cord will smooth out network problems, but other
system components may also need to be replaced. Tests
at this firm showed that the patch cord was ill-matched to
the horizontal cable (Figure 22). Note in particular how the
green and brown pairs differ in impedance from each other.
The impedance spikes occurring at five meters into the run
(viewing left to right) are the poorly matched interface
between the plug on the patch cord and the jack. Simply
replacing the existing patch cord with a TruePatch cord
yields a noticeable improvement in the trace. Note, however,
that since the jacks were not part of a matched system, the
same spike occurs at the plug/jack interface (Figure 23).
7
01020304050607080
40
60
80
100
120
140
Distance (Meters)
IMPEDANCE MISMATCH OF THE PATCH CORD, THE PANEL AND THE CABLE
IMPEDANCE MISMATCH OF THE CABLE CONDUCTORS

Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 18: A channel with an impedance mismatch and mismatched
cable pairs.
-20 0 20 40 60 80 100 120
60
70
80
90
100
110
120
130
140
150
160
Frequency (MHz)
<<10BT 100BT
Impedance (Ohms)
——
——
PAIR 1 ——

——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 19: Viewed in the frequency domain, it is apparent that the
channel is way out of specification.
0 10 20 30 40 50 60 70 80 90
40
60
80
100
120
140
Distance (Meters)
IMPEDANCE IMPROVEMENT USING A TRUEPATCH PATCH CORD
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 20: The same channel with a TruePatch cord.
-20 0 20 40 60 80 100 120
50

60
70
80
90
100
110
120
130
140
150
Frequency (MHz)
<<10BT 100BT
IMPROVEMENT USING A TRUEPATCH PATCH CORD
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 21: The addition of TruePatch greatly improves channel performance.
0 5 10 15 20 25 30 35 40 45 50
40
60
80
100
120

140
Distance (Meters)
IMPEDANCE MISMATCH OF THE PATCH CORD, THE PANEL AND THE CABLE
IMPEDANCE MISMATCH OF THE CABLE CONNECTORS
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 22: Patch cord is ill-matched to horizontal cables.
0 4 8 12 16 20 24 28 32 36 40
40
50
60
70
80
90
100
110
120
130
140
Distance (Meters)
IMPEDANCE IMPROVEMENT USING A TRUEPATCH PATCH CORD
Impedance (Ohms)

——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 23: Replacement of patch cord yields a noticeable improvement.
Replacing a
patch cord with
a TruePatch cord
can smooth out
network problems.
KRONE: 800-775-KRONE www.kroneamericas.com
No part of this document may be reproduced without permission. ©2001 KRONE
®
Incorporated
KRONE and TrueNet are trademarks of KRONE
®
Incorporated. All other trademarks are property of their respective owners.
KRONE
®
Incorporated
North America Headquarters
6950 South Tucson Way
Englewood, CO 80112-3922
Telephone: (303) 790.2619
Toll-Free: (800) 775.KRONE

Facsimile: (303) 790.2117
www.kroneamericas.com
The original patch cord causes the channel’s impedance
over frequency to drop below 85 ohms at lower than
100 MHz, meaning potentially serious data transmission
problems (Figure 24). The TruePatch
™
cord in the same
channel smooths out the frequency trace somewhat,
actually bringing most of the trace into compliance.
However, the lack of fine tuning throughout the whole
channel means that even the addition of the TruePatch
cords will not completely eliminate throughput
problems (Figure 25).
A benefits administration company — This last
installation example, occurring at a benefits administration
company, shows huge mismatches and inconsistencies,
particularly with cross-connect blocks and poorly installed
cable. This customer with a 10BASE-T network was
considering an upgrade to 100BASE-T (Figure 26).
TruePatch cords aren’t able to overcome the cross-
connect block, but they do manage to smooth out the
trace somewhat (Figure 27). This node will never run
100BASE-T effectively, as the massive oscillations will
cause tremendous signal degradation (Figure 28). The
TruePatch cord makes some difference, but not enough.
Our recommendation: don’t waste money on 100BASE-T
active equipment without first fixing the infrastructure
(Figure 29).
8

0 4 8 12 16 20 24 28 32 36 40
Distance (Meters)
40
50
60
70
80
90
100
110
120
130
140
Impedance (Ohms)
IMPEDANCE MISMATCH OF THE PATCH CORD, THE BLOCK AND THE CABLE
HARSH BENDS AND OVER TIGHTENED CABLE TIES
TYPICAL CHARACTERISTIC OF OVER PULLING TENSION
IMPEDANCE MISMATCH OF THE CABLE, THE STATION OUTLET AND THE PATCH CORD
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 26: Without TruePatch, this channel has huge mismatches
and inconsistencies.
0 26 52 78 104 130 156 182 208 234 260

Frequency (MHz)
40
50
60
70
80
90
100
110
120
130
140
Impedance (Ohms)
10BASE-T
100BASE-T
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 28: This node will not run 100BASE-T effectively.
0 4 8 12 16 20 24 28 32 36 40
Distance (Meters)
40
50
60

70
80
90
100
110
120
130
140
REDUCED IMPEDANCE MISMATCH OF THE BLOCK AND THE CABLE
USING A TRUEPATCH PATCH CORD
REDUCED REFLECTION POINTS
REDUCED IMPEDANCE MISMATCH
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 27: With TruePatch, the traces smooth out.
0 26 52 78 104 130 156 182 208 234 260
40
50
60
70
80
90

100
110
120
130
140
Frequency (MHz)
10BASE-T
100BASE-T
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 29: The TruePatch cord helps this node, but cannot remedy
all the infrastructure problems.
Check Your
Infrastructure First
Armed with this
kind of evidence, we
would hope that most
companies would heed
our warning and look
first at network
infrastructure before
investing in more

software, active
equipment and/or
more bandwidth. An
active system test is
a completely plausible
way to diagnose
network problems and,
as evidenced, it can
go a long way toward
pointing out some
network performance
deficiencies.
0 26 52 78 104 130 156 182 208 234 260
Frequency (MHz)
40
50
60
70
80
90
100
110
120
130
140
Impedance (Ohms)
10BASE-T
100BASE-T
——
——

PAIR 1 ——
——
PAIR 2 ——
——
PAIR 3 ——
——
PAIR 4
Figure 24: Original patch cord causes the impedance to drop.
0 26 52 78 104 130 156 182 208 234 260
40
50
60
70
80
90
100
110
120
130
140
Frequency (MHz)
10BASE-T
100BASE-T
Impedance (Ohms)
——
——
PAIR 1 ——
——
PAIR 2 ——
——

PAIR 3 ——
——
PAIR 4
Figure 25: The TruePatch cord helps to smooth out the
frequency trace.