Test Results 5-2
When there is a cable fault (open or short), the
TDR will automatically display the distance to the
fault with an accuracy of ±3ft (1m).
Wire map Testing Active LAN Links
Running the wire map test on active LAN links can produce results
that indicate a wire map failure when there is none. Most
10/100Mbps Ethernet switches internally short the unused pairs
(4/5, 7/8) since they are not used at these speeds. In this case,
SIGNALTEK will detect the shorted pairs at the switch. This is not a
cabling problem; the tester is simply detecting the internal short on
the switch. The benefit is that since a short has been created, the
TDR can accurately measure the distance to the switch.
Gigabit switches use all four pairs. Therefore, shorts will not be
indicated when performing a wire map test into a Gigabit Ethernet
device. In this case, the length information will be estimated from
the Gigabit DSP.
Link Establishment
Link Establishment displays the connection speed of the active
device at the other end of the cabling link. Possible link speeds are
10/100/1000Mbps. This is the maximum speed of the other end of
the link. The actual network bandwidth may be less than the link
speed.
Link Establishment also displays the MDI/MDIX results for the link.
Normally, Twisted Pair ports must be connected so that the
Transmit pair on one end is connected to the Receive pair on the
other end, and vice versa. If the cabling is done so that Transmit on
one end is wired to Transmit on the other, and Receive is wired to
Receive, the link will not display.
Hubs and switches are deliberately wired opposite of the way PC
network cards are wired, so that when a hub or switch is connected
to a PC, a "straight through" Ethernet cable can be used and the
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