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Chapter 6: Operation
FAQ: What is the difference between Level 1 and Level 2
and when do I use it?
Level 1 verification tests for length,
opens, shorts, split pairs (including distance to the fault) along
with propagation delay, skew, NEXT, FEXT, and cable category
measurements. Level 1 testing uses simulated digital signals to
test the cable. Level 2 adds to the testing with the use of real live
data from a NIC, hub, or switch. Use Level 1 for new cable
installations or anytime a LAN device (hub, switch, PC) is not
available.
Figure 6-17. Testing Link Pulses from a Gigabit device.
Figure 6-18. Testing Link Pulses from a 100-Mbps device.
The first step in the Level 2 process is to read the link pulses of
the LAN device and determine its advertised capability. Every
LAN device broadcasts its capability in terms of speed, duplex,
and other features (known as “advertised” capabilities) to other
LAN devices.
