Verilink PRISM 3001 (34-00186) Product Manual - Manual (Page 33)

Front Panel Testing 3-3
15 PLB: This LED lights continuously when the network interface is in a payload
loopback. With LLB, this LED also lights continuously when the unit is in NET
MLB or flashes when the unit is in DTE MLB.
16 FLB: This LED is active for port loops. It lights continuously when the unit is in a
fractional (high-speed port) loop.
17 TST: This LED lights continuously during a Far or a Local test. It flashes while
loopback codes are transmitted at the start of a Far test and while unloop codes are
transmitted at the end of a Far test.
18 ERR: This LED lights when BERT pattern errors are detected.
19 Test Switch: This switch (FAR /LOC) is used for local testing. Refer to Test
Switch for more information.
20 Pattern Select: This switch determines the BERT pattern sent by the unit when the
test switch (item 19) is in the FAR or LOC position. Refer to BERT Pattern Select
on page 2 -4.
21 SUPV: The supervisory jack provides direct terminal access to control the unit and
gather status/facility performance data. Refer to Supervisory Port on page 2 -4 for
more information.
Front Panel
Testing The previous section gave a brief description of each front panel control and LED
indicator. This section explains the front panel test functions. Testing may also be
performed using software control from the EM8000 Network Manager, 8100A Site
Controller, or the terminal interface program (refer to the Terminal Operations chapter).
Test
Switch
This switch (labeled FAR/LOC) is used for local testing. When in the FAR
position, the unit sends five seconds of IBLC (in-band loop codes), then switches
to the test pattern selected by the Pattern Select rotary switch. When transmitting
IBLC, the test LED blinks. When transmitting a test pattern, it lights continuously.
The ERR LED lights for one second when a bit error or sync loss on the returned
data is detected.
When the test switch is returned to the normal center position, the unit sends five
seconds of loop down code (100) and then returns to its normal operating mode.
When the Test switch is set to Local, the unit performs a network LLB as shown in
loopback diagram #2 (see Figure 4-7 on page 4-11). The LLB and TST LEDs light.
Test
Access
Jacks
Units with four bantam jacks provide access to the T1 line on the DTE side of the
CSU. Two (MON) are used for non-intrusive network monitoring in both
directions. The other two (NET) allow inserting signals to and from the network
using a T1 test set. This is shown in Figure 3-2.