Specifications
7-88
Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
Chapter 7 Switch Operating Procedures
Configuring a line loopback
Configuring Loopback Line Tests on AXSME Cards
Once the physical connection is established, you need to use the CLI to put the connection into loopback
mode.
The following types of loopback are supported on the AXSME:
• Far-end line loopback - Loopback appears at the far-end of the CPE when you send a loopback
activation code from the AXSME. The CPE enters a loop mode in which it returns the received data
back to the AXSME. The CPE continues to return the data back until it receives a no-loopback
request.This kind of loopback can be used to run tests, such as BERT.
• Far-end payload loopback- Loopback is similar to FarEnd loopback, except that the payload portion
of the data is re-transmitted. Framing is done by the Far end again.
• Remote line loopback - Loopback returns the remote data back to the far end. The received data
stream is looped back into the transmit path, overriding the data stream created internally by the
framer.
• Local loopback - Loopback allows the transmitted data to be looped back into the receiving path. It
can be used to test the internals of the AXSME card.
Once your physical line is connected, you can perform a loopback test using the following procedure.
Step 1 Connect a single line to the appropriate transfer and receive ports on the backcard you want to test.
Step 2 Establish a configuration session with the active AXSM or AXSME card using a user name with
SERVICE_GP privileges or higher.
Step 3 Enter the dsplns command to display the configuration for all lines on the current card.
Step 4 Enter the addlnloop command to add a line loopback. Table ** describes the possible options for each
AXSM card type. The addlnloop command parameters are different, depending on which time of AXSM
on which you are adding a loopback line.
addlnloop <-line type> <bay.line> -lpb <loopback type>
Table 7-44 addlnloop Command Parameters
Parameter Description
-Line type Replace line type of line on which you are configuring loopback.
On an AXSM card, possible lines are:
• -ds3
• -sonet
On an AXSME card, possible lines are:
• -ds3
• -e3
• -sonet
• -ds1
• -e1
Note On an AXSME-32 card, -ds1 is the only possible option.