Chapter 4 Maintenance
19
4 Maintenance
4.1 Self-Test
At system power up, a complete self-test routine is run to check all I/O ports, read/write memory, and data
paths to validate system integrity. Various system diagnostic methodology can be found in the following
paragraphs.
4.2 Diagnostics
A 15-bit register PRBS (Pseudo-Random Bit Sequence 2
15
-1) pattern, is used in the Loop-IP 6610. The
PRBS test pattern is used to test local Loop-IP 6610 system integrity by local loopback test. It can also be
used to measure the E1 line quality. The diagnostics scenario is as follows:
1. First, have the remote facility to loopback the DS0 channels.
2. Then, activate the local PRBS diagnostics operation. Use the Test command to enable PRBS.
3. The FULL PRBS diagnostic uses a framed pattern. This is useful for testing full E1 loopbacks at the far-
end.
When the PRBS pattern sync is found, a bit error counter tracks total bit errors. It is advised to send
PRBS for more than 15 minutes interval to evaluate the quality of loop condition and facility reliability.
4.3 Loopbacks
4.3.1 Near End Loopbacks
The near end loopbacks such as line loopback and payload loopback are activated by the local IP6610 DS1.
The loopbacks are at the near end facility. The following paragraph describes each loopback in detail.
Note: Deactivate the near-end loopbacks from the terminal.
MAC
Media Access
Controller
Processor
Line
Port
(DS1)
DS1 Line
Payload
Loopback
Line
Driver
Line
Receiver
Line
Loopback
D
S
1
F
R
A
M
E
R
Figure 4-1 DS1 Loopback Block Diagram
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