Enterasys SBUQHS/QHB, User Manual

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Module Description
80-14001000-03 2–7
2.4 SBUQLB and SBUQHB
These units provide an additional 4 ports for connection to the DLC, and
as a consequence occupy 2 slots of the shelf. Fully automatic backup
and restoral features are provided with these modules.
Rear card by-pass relays on all four pairs of ports allow for hardwire
through connection of the DLC to the User equipment in the event of
power failure to the shelf.
All the dial access facilities provided with SBUQLS are provided on the
SBUQLB and similarly for the SBUQHS and SBUQHB. Full backup
facilities are provided with the SBUQHS and SBUQHB.
2.4.1 Circuit Failure
Automatic backup due to detection of DLC failure occurs if any of the
following conditions are detected:
•
No data is received from the DLC.
•
No clock is detected from the DLC.
•
The I/DSR signal from the DLC goes to the OFF condition.
•
The C/DTR signal from the User DTE equipment goes to the ON
condition.
User selectable time-outs can be independently set for all of the
detection facilities mentioned, except C/DTR from the DTE.
2.4.2 Circuit Restoral
Automatic restoral is effected by passing ‘Talkwire’ over the DLC to
verify that an error free path has been re-gained, before switching user
data back onto the DLC. The time for Talkwire to verify the DLC for
integrity can be set by the user.
2.5 Talkwire
Talkwire calls for management or call control can be made or received
on all ports simultaneously on the SBUQLS/QLB.
When a Talkwire call is made to the SBUQLS/QLB in order to access its
command menu, the remote user will be prompted for a password - this