3Com NETBuilder SI, SuperStack II manual Performing, Loopback Tests

Performing Loopback Tests 133

Performing	This section describes the bridge/router response to a local loopback
Loopback Tests	assertion and how to perform a loopback diagnostic test on the WAN
	and serial ports. It also describes the steps required to perform additional
	types of loopback tests for a T1/FT1 module.
Response to Local	If the bridge/router is connected to a DTE that asserts a local loopback
Loopback Assertion	signal, the bridge/router displays:
	Path x Detected DTE Loopback ON, switching to echo mode

Performing a Loopback Test on the ISDN Port (43x, 53x, 44x and 54x)

The bridge/router in echo mode transmits the received data back to the DTE.

When the signal is removed, the bridge/router displays:

Path x Detected DTE Loopback OFF, switching to normal mode

This section describes how to perform a loopback test on the built-in ISDN port on model 43x, 53x , 44x, and 54x bridge/routers.

Figure 9 shows the data flow that occurs when this loopback test is performed. Both B channels occupy the same physical connector and no TA is required in this configuration.

Figure 9 ISDN Loopback Testing

Port 3

Port 4

Both channels (B1 and B2)

occupy the same physical connector

B1 (Path 3.1)

ISDN

B2 (Path 3.2)

Prerequisites

Before beginning this procedure, complete the following tasks:

■Attach a console or Telnet to your SuperStack II bridge/router.

■Configure the ISDN port according to “Configuring ISDN on the WAN Port (43x, 44x, 53x, and 54x)” on page 70.