MCM1000S/L GBE module
05
In Test mode, as long as no link failure is detected, data is communicated normally.
In case of a link failure in LST OFF mode, the Test Mode will provide a visual
indication of the active and operative links and indicate the failing link segment.
Figure- 2 (below) depicts the sequence of events when the LST DIP switches are
changed to Test Mode, following a link failure occurred in LST OFF mode.
S3
S4
S4
N
E
T
W
O
R
K
D
E
V
I
C
E
N
E
T
W
O
R
K
D
E
V
I
C
E
MCM1000S
GSM1000/MA
TX
TX
TX
TX
RX
RX
TX
RX
RX
RX
A
B
P
O
R
T
1
P
O
R
T
2
P
O
R
T
2
P
O
R
T
1
S3
Idle signal
TX
RX
Link On
Idle signal
Link On
Link Segment OK
Link Segment OK
Failed Link
1000Base-LX
1000Base-SX
1000Base-SX
MetroStar
S3
S4
S4
N
E
T
W
O
R
K
D
E
V
I
C
E
N
E
T
W
O
R
K
D
E
V
I
C
E
MCM1000S
GSM1000/MA
TX
TX
TX
TX
RX
RX
TX
RX
RX
RX
A
B
P
O
R
T
1
P
O
R
T
2
P
O
R
T
2
P
O
R
T
1
S3
Idle signal
TX
RX
Link On
Idle signal
Link On
Link Segment OK
Link Segment OK
Failed Link
1000Base-LX
1000Base-SX
1000Base-SX
S3
S4
S4
N
E
T
W
O
R
K
D
E
V
I
C
E
N
E
T
W
O
R
K
D
E
V
I
C
E
MCM1000S
GSM1000/MA
TX
TX
TX
TX
RX
RX
TX
RX
RX
RX
A
B
P
O
R
T
1
P
O
R
T
1
P
O
R
T
2
P
O
R
T
2
P
O
R
T
2
P
O
R
T
2
P
O
R
T
1
P
O
R
T
1
S3
Idle signal
TX
RX
Link On
Idle signal
Link On
Link Segment OK
Link Segment OK
Failed Link
1000Base-LX
1000Base-SX
1000Base-SX
MetroStar
Figure
– 2 LST ON - Test Mode
4. Isolation of a failed link segment
:
a. To isolate the failed link segment (between the GSM1000/MA and the Network
Device B, the LST DIP switch
S4
in MCM1000S module is turned ON
(Test mode) via the remote management
This action generates an idle signal to be transmitted from MCM1000S to
Network Device A turning On the Link at Network Device A. This indicates
that the link segment between the MCM1000S module and Network Device
A is operative.
b. The DIP switch S3 (port1>port2) at the GSM1000/MA device must be physically
set to Test Mode which in this case will cause the F/O Link LED at
MCM1000S/L (port2) to lit (Link ON)
This indicates that the link segment between the MCM1000S and GSM1000/MA
is intact and operative.
c. The above tests are an absolute indication that the failure is in the link segment
between the Network Device B and the GSM1000/MA port 1
d. After having located and repaired the failing segment, it is advisable to turn the
MCM1000S LST DIP switches to their default setting.
Notes
(when GSM1010/MA or GSM1000/MA acts as a remote device ):
To preserve the link integrity for the MA inband management, the DIP switch S3
and S4 (in GSM1000/MA or GSM1010/MA) are by default set to Test Mode (LST ON)
Similar default setting applies to the MCM1000S module.
5. The correct deployment of the LST mode of operations in the FibroLAN MA managed
devices depends primarily on the network topology.
If the attached Network Devices (switches, routers) can provide an alternate path in case
of a link failure, then it is advisable and recommended to deploy the LST OFF mode (in
this case the Network Device is alerted of a link failure).
In case of a link failure, it is necessary to switch to Test mode in order to locate the failed
link segment. (via DIP switches or appropriate MA management commands)
6. On the other hand, if the attached Network Devices are dumb units and are unable to
provide an alternate path, then it is recommended to deploy the LST DIP switches in
Test mode (LST ON) which is the
default setting.
