7.13 About Diagnosing Speciļ¬c Problems

7.13.1 Network Communications Failure

7.13.1.1 Symptom

The system is unable to communicate over the network.

7.13.1.2 Action

Yoursystem conforms to the Ethernet 10BASE-T/100BASE-TX standard, which states
that the Ethernet 10BASE-T link integrity test function should always be enabled on
both the host system and the Ethernet hub. The system cannot communicate with a
network if this function is not set identically for both the system and the network
hub (either enabled for both or disabled for both). This problem applies only to
10BASE-T network hubs, where the Ethernet link integrity testis optional. This is not
a problem for 100BASE-TX networks, where the test is enabled by default. Refer to
the documentation provided with your Ethernet hub for more information about the
link integrity test function.
If you connect the system to a network and the network does not respond, usethe
OpenBoot PROM command watch-net-all to display conditions for all network
connections:
ok watch-net-all
For most PCI Ethernet cards, the link integrity test function can be enabled or
disabled with a hardware jumperon the PCI card, which you must set manually.
(See the documentation supplied with the card.) For the standardTPE and MII main
logic board ports, the link test is enabled or disabled through software.
Remember also that the TPE and MII ports share the same circuitryand as a result,
you can use only one port at a time.
Note - Some hub designs permanently enable (or disable) the link integrity test
through a hardware jumper.In this case, refer to the hub installation or user manual
for details of how the test is implemented.
Diagnostics and Troubleshooting 225