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Performing Loopback Tests 133
Performing
Loopback Tests
This section describes the bridge/router response to a local loopback
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
Loopback Assertion
If the bridge/router is connected to a DTE that asserts a local loopback
signal, the bridge/router displays:
Path x Detected DTE Loopback ON, switching to echo mode
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
Performing a
Loopback Test on the
ISDN Port (43x, 53x,
44x and 54x)
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
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.
B1 (Path 3.1)
B2 (Path 3.2)
ISDN
Both channels (B1 and B2)
occupy the same physical connector
Port 3
Port 4