DSU Operations
5-133610-A2-GB41-60 March 1999
Table 5-5
Backup Branch Menu Selections
Current
DBM Mode Menu
Selection Effect
Idle Bkup
Dial
Dial out, establish, and switch to dialed link (Dial Backup mode).
Dial out and establish dialed link (Standby mode). The data is routed
over the DDS circuit.
Standby Disc
→Dial
Disconnect dialed link (Idle mode).
Switch data to dialed link (Dial Backup mode).
Dial Backup DrBU
→DDS
Disconnect dialed link and switch to DDS (Idle mode).
Switch data to DDS (Standby mode).
Aggregate Switch
When AggrSwitch (Aggregate Switch) is enabled, the
backup commands have a different effect:
•Bkup is used to initiate a point-to-point backup or a
full multipoint backup. The DSU disconnects from
the DDS line and reverts to the timing source
specified by the AgSw Timing (Aggregate Switch
Timing) configuration option. Do not initiate this
command for a partial multipoint backup.
For multipoint applications, data is automatically
bridged to the aggregate port as well as the DDS
line when the AggrSwitch configuration option is
enabled,
•DrBU is used to terminate a point-to-point or full
multipoint backup. The DSU resumes transmission
on the DDS line. The DSU timing is specified by
the DSU TxClkSource configuration option.
The DBM’s mode determines the menu that appears
when Bckup is selected.
With the addition of the TDM or MCMP circuit card,
the DCP operation remains unchanged while in Idle mode
for the following:
•Enabling, disabling, or placing the DBM in Dial
Backup or Standby mode.
•Disconnecting the dial connection, switching data
to the dial connection and switching to the DDS
circuit.
To learn how to enable, disable, or place the DBM in
Dial Backup or Standby mode while in Idle mode, as well
as how to disconnect the dial connection, switch data to
the dial connection, and switch to the DDS circuit, refer to
the COMSPHERE 3600 Series Data Service Units,
Models 3610 and 3611, Dial Backup Module and SNA
Diagnostic Interface Options, Applications Guide.
Bridge
When the DSU is configured as an extended bridge
(EBrdg), the Bckup menu is displayed; however, the
DSU-DBM or DSU-DBM-V is always in Dial Backup
mode. If an attempt to drop backup (DrBU) is made, a
Conflict w/Envir message is displayed.
When a DSU is configured as a central-site bridge, a
DBM circuit card can be installed, but the DBM must be
disabled. When the TDM or MCMP circuit card is
installed, only two sections are displayed: one turns the
bridge ON (Bkup) and the other turns it Off (DrBU).
Select Bkup to activate the bridge, disconnect the DDS
line from the bridge, and switch to internal timing; select
DrBU to deactivate the bridge; to connect the DDS line to
the bridge and switch to DDS timing.
The digital bridge’s mode determines the menu that is
displayed when Bckup is selected.