Ethernet LAN Newbie: cheap cable tester?

How do I test to see if a particular cat 6 connection will run at full
speed?

I'm not sure that every punchdown we've done is a good one. Is there an
easy way to test the quality of a connection?

There are several different types of measurements that have to be done,
most over a range of frequencies. It's the sort of thing that is easy
if you have the right tool, and cumbersome to impossible otherwise.

Looking around a bit and sampling some prices, there appear to
be a number of tools available, including:

Ideal Lantek 6, about $6000 to $9000
Fluke DTX-1200, about $7000 to $13000 (possibly for the exact same thing)
Fluke DSP-4000, about $6000 to $7000, DTX is the newer line
Fluke Etherscope, about $20000-ish, possibly superceeded
Agilent FrameScope 350 plus DualRemote 350
Agilent Wirescope 350, about $5000
Test-um NT950 Validator, about $1100


These are only a brief survey, not recommendations. I haven't
used any of these; I've never heard of Test-um before.
I have used the much older Fluke LanMeter (Cat 5); it was fairly simple
for the ethernet tests (more complex for fibre tests.)

I see the Fluke DTX-1200 quoted at 9 seconds for a full Cat6 test
in one place, and quoted at 12 seconds in another. I didn't look
to see whether that's a general improvement over the lifetime of the
product, or if special licenses or extras are needed for the faster
testing.

There also appears to be the Fluke CableIQ Qualification Tester, about
$1000. According to the flukenetworks.com information,

  Qualifies - Sees if your existing cabling has the bandwidth to support
    voice, 10/100, VoIP or Gigabit Ethernet

  Troubleshoots -- shows why existing cabling cannot support the network's
    bandwidth requirement (e.g., crosstalk at 11 meters)

Hmmm, you might need the CIQ-GSV "CableIQ Gigabit Service Kit", which
probably costs more.

Try it and see.  You can always take two hot laptops with built-in
GBE and run `ttcp` or `netperf`.  Try across a known good patchcord
to see what the machines are cabable of.  Don't expect them to be
able to saturate the link (120 MByte/s) but record what they can
do (30-50) and see if the test links are close (1-5%).  If the
links are 12 or below, it's likely they've fallen back to 100,
most likely due to a bad pair.


Walter has given you the pricing rundown on certification
equipment.  Simple continuity/wiremaps are much cheaper.
You could also call a local dcom cabling contractor.  If not
busy, she should be able to certify the links for $20-50 each.

I expect less than 10% of all wiring has been certification
tested, mostly due to the cost of test equipment.  The wire
that has been tested was mostly installed by govt/megacorps
who always want a spec.  They will occasionally save themselves
some very nasty, hard to find network problems (split pair).

-- Robert

Robert Redelmeier wrote:

(snip)


It shouldn't be so hard to build a simple detector for
split pairs, though I don't know that anyone has done it.

If they are terminated, and maybe even if they aren't,
send a balanced signal down each pair, one at a time,
and measure the signal on the other pairs.  Though if one
is actually trying to do it right, the probability of
continuity on each wire (that is, pin 1 to pin 1, pin 2
to pin 2, etc.) being right and the pairs being wrong
is fairly small.   I used to know someone with a little
box with eight LEDs that would plug into one end, and
a transmitter for the other end.  The LEDs should light
in sequence if the pins were connected right.  Simple,
but will catch a large fraction of errors.

-- glen