Solutions to Common Problems
cable in appendix A, "Cables and Connectors" for pinouts and correct
cable wiring. A category 5 cable tester is a recommended tool for every
100Base-T network installation.
Improper Network Topologies. It is important to make sure you have
a valid network topology. Common topology faults include excessive
cable length and excessive repeater delays between nodes. If you have
network problems after recent changes to the network, change back to
the previous topology. If you no longer experience the problems, the new
topology is probably at fault. Refer to the guide entitled Designing HP
AdvanceStack Workgroup Networks for topology configuration guide-
lines. This guide is included on the HP AdvanceStack Products CD-ROM
that comes with the HP Switch 208/224 Management Module. The guide
can also be found online at the HP World Wide Web site,
In addition, you should make sure that your network topology contains
no data path loops. Between any two end nodes, there should be only one
active cabling path at any time. Data path loops will cause broadcast
storms that will severely impact your network performance. If you wish
to build redundant paths between important nodes in your network to
provide some fault tolerance, you should install a Switch 208/224 Manage-
ment Module and enable Spanning Tree Protocol support on the switch.
This ensures that only one of the redundant paths is active at any time,
thus avoiding data path loops.
Switch 208/224-Specific Connectivity Situations:
For the Switch 208T and 224T, there are a few specific network connec-
tion situations you must avoid:
Wrong transceiver type -- You have installed an HP 100VG trans-
ceiver into the transceiver slot. The slot is specifically designed to be
used with the HP 100Base-T transceivers. Make sure that you install
only "B" model or later 100Base-T transceivers in this slot, for
example HP J3192B.
Wrong network speed connected -- You have connected a
10 Mbit/s cable to one of the 100 Mbit/s ports. On the Switch 208/224,
the 100 Mbit/s ports cannot operate at 10 Mbit/s.
Expansion Module installed -- When you install an optional expan-
sion module in the back of the switch, it uses the port 1 circuitry to
communicate to the rest of the network through the switch. In this
case, the port 1 RJ-45 connector (and only that connector) becomes
disabled, as shown by the port 1 disabled LED on the front of the