HP J2415A Installation And Reference Manual page 30

Installing the HP AdvanceStack Hub
Using Unbundled (4-pair only) Cables
You can used unbundled cables to connect to devices that operate in either
private mode or promiscuous mode. A private mode device (such as a
typical end node) receives only those packets intended for it. A
promiscuous mode device (such as a LAN analyzer or cascaded hub)
receives all packets. A hub port that detects a promiscuous device assumes
that an unbundled cable is being used.
Using Bundled (25-pair) Cable
If you are presently using bundled twisted-pair cable (25 or more
twisted-pairs) from a cross-connect block, wiring closet, or other
intermediary connection, you will need to attach RJ-45 connectors to the
appropriate sets of 4-pair wires in the cable for connection to the HP 100VG
hub. For the LAN port RJ-45 connector pinouts and wiring diagrams, refer
to appendix A.
C a u t i o n
Some special wiring concerns exist with promiscuous devices such as a
cascaded hub, a switch, or a LAN analyzer.
When connecting any promiscuous device with bundled cable, you should
select the "Some Bundled" hub cabling feature in HP Stack Manager. This is
to prevent signal interference (crosstalk), which can result in unreliable
network operation.
If no promiscuous devices are connected with bundled cables, selecting
"None Bundled" will provide the best performance. Note that the cable must
be unbundled through the entire path—from the hub to the device.
If you have a promiscuous device and select "none bundled", the use of
a bundled cable with a promiscuous device will cause signal interference.
Individual wire pairs may exhibit significant near-end crosstalk which can
interfere with network operation. Verification of your cable system may be
necessary if a port does not train properly.
Because each LAN port uses four pairs, a bundled cable containing 25
twisted pairs can connect up to six 100VG LAN ports. Select "Some
Bundled" in HP Stack Manager for a port using bundled cable.
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