Chapter 6 System Testing Gen 3 Site Controller System Manual
Remotely Looping Back the T1 Site Controller for BER Testing
6-22 68P80801E30-A 5/1/2002
The T1.403, T1 payload loop-up and down commands transmit on the T1
Extended Super Frame Facility Data Link. The payload loop-up,
bit-oriented message is 00010100 11111111, with the right most bit
transmitted first. The payload loop-down, bit-oriented message is
00110010 11111111, with the right most bit transmitted first.
Starting and Stopping Loop-Backs
If someone starts a line loop-back using the in-band loop-up code, he will
need to terminate loop-back using the in-band loop-down code. The site
controller has two different loop-back decoders. One decoder is for in-band
signaling. The other decoder is for facility data link signaling.
A T1.403, line loop-down, bit-oriented message on the FDL will not
loop-down the site controller if it was looped-up with a in-band loop-up
code. Likewise, a site controller that was looped-up with a T1.403, line
loop-up, bit-oriented message on the FDL will not de-loop if an in-band
loop-down code is sent.
Payload loop-back is a case by itself. The only way to start a payload
loopback is with the T1.403, payload loop-up command. The only way to
loop down is with the payload loop-down command.
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