Справочник Пользователя для 3com SuperStack II

A

PPENDIX

 A: T

ROUBLESHOOTING

This section describes how to perform a loopback test on a serial port.

Figure 14 shows the data flow that occurs when a loopback test is 
performed on a serial line. A modem or CSU/DSU is required in this 
configuration.

Figure 14   Serial Loopback Testing

Before running the serial loopback test, complete the following tasks:

■

Attach a console or Telnet to your bridge/router.

■

Place the modem or CSU/DSU in local loopback test mode. For 
information, see the documentation that accompanies your modem 
or CSU/DSU.

■

Verify the path and port number of the serial port you are testing by 
referring to Table 14 or Table 15 on page 69.

To perform a loopback test on the serial port, follow these steps:

1 Set the line type to Leased using:

SETDefault !<path> -PATH LineType = Leased

2 Set the owner of the serial port you are testing to LoopBack using:

SETDefault !<port> -PORT OWNer = LoopBack

3 Select the loopback test mode by entering:

4 Specify the number of seconds that the test should run using:

DLTest TestDuration <seconds>

If you do not enter a value, the test will run indefinitely. However, use 
caution when running the test for a specified duration. The test ends 
abruptly as soon as the time duration expires, and a discrepancy between 
the number of packets transmitted and the number received may result.

5 Start the serial loopback test by entering: