Metrodata FM4900, User Manual

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TEST & TROUBLESHOOTING
55 76-02-011F
9 . 3. 2 NI Local Loop
When the LOCAL LOOP is activated the signal received from the local E3 transmit port is
passed directly back to the local E3 receive port. The signal from the remote DTE passes
through the remote FM4900 and is looped at the local E3 port.
Figure 9. 5 NI local loop test
This therefore validates:
a) the local DTE cable and the local FM4900 if the local DTE recognises its own signals
b) the remote DTE cable, the remote FM4900 and the E3 link if the remote DTE recognises
its own signals.
Notes:
a) The DTE may also activate the DTE (LOCAL), NI LOCAL or NI REMOTE LOOPS using
two of the HSSI control lines (LA and LB). These loops may also be activated from the
TESTING menu.
b) The DTE EXTERNAL LOOP may only be activated via the TESTING menu.
9 . 3. 3 Remote management during testing
Care must be taken when testing. If the FM4900 is managed with SNMP or Telnet, and if the
LAN to which the NMS is connected passes over the wide-area link to which the FM4900 is
interfacing. It may be possible to lose contact with the FM4900.
For example, if a local NMS is in contact with a remote FM4900 via a remote segment of
LAN and a router, and the remote FM4900 is set to loopback, then connection with the
remote router (and therefore the remote FM4900) is lost.
It is therefore important to ensure that control of FM4900 testing is exercised on a local basis,
or that there are alternative paths available for management when remote testing is
performed.
HSSI
HSSI