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CHAPTER 6: Operation
6.3.3 L
OOPS AND
P
ATTERNS
The following section describes the Remote Loopback/BER test modes.
Remote Digital
When Remote Loop/511 or Remote Loop/511/E is enabled via the front-panel
switch, the remote unit’s restart timer is set to one minute. This is because when
the 511/511E generator is initiated on the local unit, the remote framer begins
seeing unframed packets. The remote Line Driver cannot distinguish the
511/511E pattern from the line being disconnected, so the restart timer has been
lengthened to allow the pattern generator to function. Once the 511/511E test is
started, the local Line Driver changes its restart timer to one minute. The pattern
originates within the processor and is sent to the remote Line Driver. It is then
looped back to the local Line Driver where it is evaluated for errors. After 45
seconds, the pattern generator will timeout and stops sending the pattern. The ER
LED will begin blinking until you turn off the 511/511E switch.
Figure 6-3. Remote Digital loop.
Symbol Indicators
This symbol designates the origination or the termination of a data path. The
direction of the arrow connected distinguishes the two data paths.
This symbol designates an invalid data path. If there is data present, it should
be ignored.
X
X
X
X
X
Framer
Processor
Processor
Framer
Pattern
Gen./Det.
Pattern
Gen./Det.
Loop
Control
Loop
Control
Line
