Enterasys SBUQHS/QHB, Руководство пользователя

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Quad User Modules
User Manual
80-14001000-03 2–6
inside the unit and it should only be opened by a qualified
service engineer. The mains supply should be disconnected
before accessing the interior.
Gefäh! Bereich. Nur für fachpersonal. Nicht öffnen
berührungsgefahr!
2.3 Functional Description
2.3.1 SBUQLS
The SBUQLS provides call originate and answering facilities with
V.25
bis, ‘X.21’, and ‘AT’ command sets, also C/DTR dialling and front
panel button control. Multiple dial stores and CLID stores are provided
for each port.
2.3.2 SBUQHS
The SBUQHS provides C/DTR dialling in addition to front panel dialling
control. Multiple dial stores and CLID stores are provided for each port.
Inverse multiplexing is provided for the four user ports, each capable of
aggregating together up to thirty 64kbit/s ISDN ‘B’ channels to provide an
N x 64 kbit/s stream, using either all ‘B’ channels for Mode 1, or N+1 ‘B’
channels for Mode 3. The extra ‘B’ channel in Mode 3 is required due to
synchronisation and channel aggregation management.
Two speed settings are available for each port:-
•
The ‘desired’ speed
•
The ‘fallback’ speed.
The ‘desired’ speed is the speed that the user would prefer to operate at,
while the ‘fallback’ is the lowest that the user will tolerate. This feature
enables a requested speed for example of 384 kbit/s to be negotiated.
However it will tolerate a specified minimum speed for example of
256 kbit/s which is acceptable for attached DTE equipment operation.
This method provides a reduced level of service if there are only four ‘B’
channels available on the system, rather than six as desired in this
example.