Setting Vcm Loopbacks; Setting Vcm Port Loopbacks; Setting Vcm Channel Loopbacks - 3Com SuperStack II PathBuilder S330 Reference Manual

Setting VCM Loopbacks

For the Voice Compression module, you can set both card/line and channel
loopbacks. When you set a VCM loopback, the MCPU sends a message to the
VCM card to perform a maintenance function, and the VCM replies with an
acknowledgment. When the VCM enters maintenance mode, it generates an
alarm to the MCPU. Only one maintenance function per port or per channel is
allowed.

Setting VCM Port Loopbacks

To set VCM port (card/line) loopbacks, follow these steps:
1 From the Loopback Menu, shown earlier in Figure 136, enter the number
corresponding to the slot number in which the Voice Compression module is
installed (7 or 8) to open the VCM Loopback menu. Figure 143 shows the VCM
T1-DSX menu. The VCM E1 menu is the same.
Figure 143 VCM Loopback Menu
2 Select [1] Set Port Loopback to open the VCM Card/Line Loopback menu. This
menu is similar to the OC3/STM-1 Loopback menu, shown earlier in Figure 139.
3 Select the option corresponding to the type of loopback you want to perform, and
set the loopback to On.
Local Card—Loops the transmit VCM output on the receive side; the transmitted
data will continue to go on the output.
Network Line—Loops the VCM received data back on the output side after the
digital data has been recovered.
Network Card—Loops the T1-DSX received payload back toward the line output.

Setting VCM Channel Loopbacks

To set VCM channel loopbacks, follow these steps:
1 From the Loopback Menu, shown earlier in Figure 136, enter the number
corresponding to the slot number in which the Voice Compression module is
installed (7 or 8) to open the VCM Loopback menu.
2 From the VCM Loopback menu, shown in Figure 143, select [2] Set Channel
Loopback.
Using Loopbacks 183