3Com S330 manual Illustrates the loopbacks for the E3 module

182CHAPTER 5: PATHBUILDER S330 DIAGNOSTICS AND PERFORMANCE STATISTICS

E3 Loopbacks The E3 module supports the following loopbacks:

Local Card—Loops the transmit E3output on the receive side. All cells coming from the E3 port card are looped through the backplane and back to the E3 port card. The transmitted data will continue to go on the output.

Network Line—Loops the E3 received data back on the output side after the digital data has been recovered.

Network Card—Loops the E3 received cell payload back toward the line output.

Figure 141 illustrates the loopbacks for the E3 module.

Figure 141 E3 Loopback Options

E3 Interface

Network Side

Network Card

Line

Payload

Local

CBR Loopbacks The following loopbacks are available for the CBR module:

Network Line—Loops the T1-DSX received data back on the output side after the digital data has been recovered.

Local Card—Loops the transmit T1-DSX output on the receive side; the transmitted data will continue to go on the output.

Network Card—Loops the T1-DSX received payload back toward the line output.

Figure 142 illustrates the CBR T1-DSX loopbacks.

Figure 142 CBR Loopback

CBR Interface

Network Side

Network Card

Local

Line

Payload