Run Bit Error Rate Test - Cisco ME-3600X-24CX Series Manual

Chapter 2 Configuring T1/E1 Interfaces
Table 2-1
Loopback
loopback diag
loopback local
local line
local payload
loopback remote
iboc
network line
network payload

Run Bit Error Rate Test

Bit error rate testing (BERT) is supported on each of the E1 or T1 links. The BERT testing is done only
over a framed E1 or T1 signal and can be run only on one port at a time.
The interface modules contain onboard BERT circuitry. With this, the interface module software can
send and detect a programmable pattern that is compliant with CCITT/ITU O.151, O.152, and O.153
pseudo-random and repetitive test patterns. BERTs allow you to test cables and signal problems in the
field.
When running a BER test, your system expects to receive the same pattern that it is transmitting. To help
ensure this, two common options are available:
OL-27620-01
Loopback Descriptions
Description
Loops the outgoing transmit signal back to the receive signal. This
is done using the diagnostic loopback feature in the interface
module's PMC framer. The interface module transmits AIS in this
mode. Set the clock source command to internal for this loopback
mode.
Loops the incoming receive signal back out the transmitter. You can
specify whether to use the line or payload.
The incoming signal is looped back in the interface module using
the framer's line loopback mode. The framer does not re-clock or
re-frame the incoming data. All incoming data is receive by the
interface module's driver.
The incoming signal is looped back in the interface module using
the framer's payload loopback mode. The framer re-clocks and
re-frames the incoming data before sending it back out to the
network. When in payload loopback, an all 1s data pattern is
received by the local HDLC receiver, and the clock source is
automatically set to line (overriding the clock source command).
When the payload loopback is ended, the clock source returns to the
last setting selected by the clock source command.
Attempts to set the far-end T1 interface into line loopback. This
command sends an in-band bit-oriented code to the far-end to cause
it to go into line loopback.
The incoming signal is looped back in the interface module using
the framer's line loopback mode. The framer does not re-clock or
re-frame the incoming data. All incoming data is received by the
interface module's driver.
The incoming signal is looped back in the interface module using
the framer's payload loopback mode. The framer re-clocks and
re-frames the incoming data before sending it back out to the
network. When in payload loopback, an all 1s data pattern is
received by the local HDLC receiver, and the clock source is
automatically set to line (overriding the clock source command).
When the payload loopback is ended, the clock source returns to the
last setting selected by the clock source command.
Cisco ME-3600X-24CX Series Switch Chassis Configuration Guide
Troubleshooting E1 and T1 Controllers
2-11