2.2.2 Cable Loopback Test
This loopback test checks the cable from the Gateway-ST to the local modem.
Before you use the cable loopback test, make sure that a cable loopback
connector (or equivalent) is installed at the end of the cable between the
Gateway-ST node and the local modem. To run the cable loopback test,
perform the following steps:
SNANCP> LOOP LINE
line-id AT CABLE
If this test fails, there is a fault with the cable. Have the cable replaced.
If the test is successful, run the modem loopback tests to further isolate the
problem.
2.2.3 Modem Loopback Tests
There are two modems between the Gateway-ST node and the SNA network.
You can test either modem with the SNANCP command:
SNANCP> LOOP LINE
line-id AT MODEM
First, test the modem at the Gateway-ST end of the communications path by
physically setting it to loopback mode (see the manufacturer’s instructions). If
the test fails, have the modem repaired.
If the test is successful, run a similar test on the remote modem to further
isolate the problem. For this test, the local modem should be set for normal
communications, and the remote modem should be set to loopback mode (see
the manufacturer’s instructions).
If the test on the remote modem is successful but you still have a problem, you
might need to have loopback tests run on the IBM equipment. Speak to your
IBM systems programmer to arrange for such tests.
2.3 DEC MicroServer Loopback Tests
There might be times when you cannot use the test facilities offered by the
DECnet SNA Gateway for Synchronous Transport software. In these cases,
you can use the loopback facilities that the DEC MicroServer hardware offers.
The following sections describe available tests and tell you how to use them.
2–10 Using Loopback Tests
