User`s guide
30
HUBs are typically older Ethernet devices that are 10 BaseT. Most
10/100 HUB like devices are now switches (see denition). LanScaper™
uses HUB as a denition for a specic Ethernet connection pin
assignment that allows it to connect directly to a NIC device using a
straight through cable.
MAC = Media Access Control - Protocol dened for addressing
network-interfaces on a unique basis. Each manufacturer of electronic
devices that interface to a MAC-controlled mechanism (like Ethernet)
must register with the IEEE and get a set of unique addresses. Each
device that manufacturer builds is assigned a single address from that
manufacturer’s set of addresses. Ethernet will not work properly if more
than one device on the LAN has the same MAC address.
MDI/MDI-X = Medium Dependent Interface, X for Crossover - The
physical cable interface dened in IEEE 802.3 is called MDI on one
end and MDI-X on the other end. The LanScaper™ refers to these
connectors as NIC and HUB respectively. A recent development in
Ethernet devices is the ability to determine what type of device is
connected on the other end of the cable and adjust itself to communicate
properly. HP invented this and calls it “Auto MDI/MDI-X”. The
LanScaper™ will recognize and report this type of device as an AUTO
device in Jack ID mode.
NIC = Network Interface Card - Typically an option card plugged
into a PC card slot that provides an Ethernet interface for that PC.
LanScaper™ uses the term NIC to dene the connector pin out that
allows for direct connection to a HUB device using a straight-through
cable.
Polarity - Ethernet transmit and receive driver chips use differential
voltages to improve noise immunity. Thus each direction of transmission
uses a pair of wires, one for the positive (+) side and the other for the
negative (-) side. Early Ethernet interface chips were not designed to
recognize and compensate for reversed cable pairs, so a crossed (+) and
(-) pair could cause problems. Modern Ethernet chips can compensate,
so the wiring is not critical, but the LanScaper™ can determine the
difference, and will report it. In the Jack ID mode the polarity is reported
as NRM or REV.
Straight-Through Cable - An Ethernet (CAT 5) cable which connects all
4 pairs in the cable straight through to the corresponding pairs in the far
end connector. This allows a NIC device to connect directly to a HUB
device.