COMSPHERE 3600 Series Data Service Units
5-12 March 1999 3610-A2-GB41-60
Backup Branch
The Backup (Bckup) branch controls operation of the
point-to-point dial backup feature. The Bckup selection
only appears when a DBM (V.32 DBM, 4-wire
Switched 56 DBM, or 2-wire Switched 56 DBM) is
installed, Central-Site Bridge (CBrdg) is enabled, or
Aggregate Switch (AggrSwitch) is enabled.
The DBM/DBM-V/DBM-S/DBM-D section discusses
the full set of available commands when a DBM is
installed. Multipoint dial backup requires a TDM or
MCMP to be installed, with the DSU-TDM or
DSU-MCMP configured as a central-site bridge
(MUX Funct: CBrdg), with an associated DBM-V,
DBM-S, or DBM-D for each remote drop (refer to the
Bridge section).
For additional DBM operation information, refer to the
COMSPHERE 3600 Series Data Service Units, Models
3610 and 3611, Dial Backup Module and SNA Diagnostic
Interface Options, Applications Guide.

DBM/DBM-V/DBM-S/DBM-D

This section discusses the full set of commands
available in the Backup branch when a DBM is installed.
NOTE
References to DBM in this guide
also apply to a DBM-V, DBM-S,
or DBM-D.
The Backup branch menu items displayed depend on
the DBM’s current operating mode:
•Idle mode – The DBM has no call in progress, but
may be either enabled or disabled. If the DBM is
enabled, the DDS circuit is carrying data and
diagnostics. If the DBM is disabled, no calls can be
initiated or answered.
•Standby mode – The DBM has a dialed or
switched 56 kbps connection to another DBM or
compatible modem, but the DDS circuit is still
active and carrying data. The dialed or Switched
56 kbps digital circuit carries diagnostic traffic
addressed to either the tributary DSU or DBM.
These diagnostics do not disrupt the DDS circuit.
•Dial Backup mode – A dialed connection is
established and is the active link, carrying data and
diagnostics.
Table 5-5 lists the current DBM modes, the available
selections, and the mode in which the selection places the
DBM.