Test-Um NT750 - Manual (Page 19)

LanScaper
TM
Appendix A: Glossary of Networking Terms
10 Base-T
100 Base-Tx
Cross-Over Cable
HUB
MAC
MDI/MDI-X
- The earliest definition of Ethernet was for 10 Million Bits per second, 10 Mbps. The
Ethernet specification defined several different cabling schemes, including T568A/B (4-pairs of
wire) and coax wiring. The 10 in 10 Base-T defines 10 Mbps and the Base-T defines T568A/B,
CAT3 cabling. 10 Base-2 defines 10 Mbps over coax. Note that the LanScaper™ PING mode
works in 10 Base-T. It relies on the legacy compatibility built in to all 100 Base-Tx equipment to
communicate. The LanScaper™ reports this in Jack ID mode as 10 Base-T.
- A newer Ethernet specification defines 100 Mbps data rate as an upgrade for higher
network bandwidth. Several different cable schemes are defined for 100 Mbps. The 100 in 100
Base-Tx defines the data rate as 100 Million Bits per second. The Base-Tx defines the cable
scheme as 2-pairs of wires in a T568A/B, CAT5 cable. Note that the LanScaper™ PING mode
works in 10 Base-T. It relies on the legacy compatibility built in to all 100 Base-Tx equipment to
communicate.
One other cable scheme defined as Base-T4 uses 4 pairs of wires in T568A/B, CAT3 or CAT5
cable. Very few Ethernet devices use this scheme, as the 2-pair(-Tx) scheme dominates the market.
The LanScaper™ can recognize and report this capability in the Jack ID mode, but it does not
operate in this mode. The LanScaper™ reports this in Jack ID mode as 100 Base-T4.
- An Ethernet T568A/B cable which connects the 1-2 pair on one end to the 3-6
pair on the other. This allows a NIC device to connect directly to another NIC device, or HUB to a
HUB. These are often used to connect one HUB (or switch) to another HUB (or switch) to enable
LAN expansion. Note that if one of the HUBs has an "UPLINK" connector, that connector can be
used with a straight through cable to connect a normal HUB port to the "UPLINK" port.
- Ethernet physical wiring is done on a point-point mechanism, but an Ethernet network is a
star network, where any device can communicate directly with any other device on that network. A
HUB is physical device that has multiple Ethernet connectors (ports) on it. Inside, the HUB
receives incoming data from any of its ports and then transmits what it receives back out on all its
ports. Thus, all communications between all devices is visible to all other devices on that LAN.
The HUB has no IP or MAC address of it's own. It is thus, a "transparent" device that merely
enables multiple Ethernet devices to communicate between themselves.
HUBs are typically older Ethernet devices that are 10 BaseT. Most 10/100 HUB like devices are
now switches (see definition). LanScaper™ uses HUB as a definition for a specific Ethernet
connection pin assignment that allows it to connect directly to a NIC device using a straight through
cable.
= Media Access Control - Protocol defined 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.
= Medium Dependent Interface, X for Crossover - The physical cable interface
defined 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.