Troubleshooting; Moves And Changes; Checking Or Disabling The Link Test - Sun Microsystems Ultra 2 series Service Manual

The link test function at the host or hub is either enabled (link test enabled or 1) or
disabled (link test disabled or 0). The IEEE 802.3 10BASE-T specification requires
that the link test be enabled at both the host and the hub.
Although link test disabled does not conform to the specification, it is often
encountered in real-world 10BASE-T network installations. Some hubs from various
vendors can exhibit any of the following:
Link test is "hardwired" enabled — link test is always enabled.
Link test is "hardwired" disabled — link test is always disabled.
Link test is configurable — the network administrator may enable or disable link
test.
C.1.11.3

Troubleshooting

If you have connected an Ultra 2 Series host to a hub using TPE cable and observe
either "no carrier" messages or fail to communicate effectively with another host in
the same network, look first at the hub. If it supports configurable link test, then
make sure "link test enabled" is configured. This is usually done by setting a
hardware switch.
If the hub does not support configurable link test, then refer to the hub
manufacturer's documentation. Check to see if your hub is hardwired for link test
disabled. If it is, refer to Section C.1.11.5 "Checking or Disabling the Link Test" on
page C-16 to disable the link test at your Ultra 2 Series host.
C.1.11.4

Moves and Changes

If the Ultra 2 Series host is physically moved to another network location or if the
hub is reconfigured, remember to refer back to
relationship between the host and the hub is functional (that is, 1-1 link test enabled-
link test enabled or 0-0 link test disabled-link test disabled), there will be no full,
regular two-way communication between the host and the hub.
C.1.11.5

Checking or Disabling the Link Test

To check the link test:
1. If you do not see the ok prompt, press the Stop (L1) and A keys.
C-16 Sun Ultra 2 Series Service Manual • July 1996
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. Unless the new network
FIGURE C-5