Paradyne COMSPHERE 3800PLUS Manual

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3600 Series Data Service Units ARDIS Abstract
Document Number 3600-A2-GZ60-00
May 1995
Purpose
This special firmware release adds the ability of ARDIS cell sites to backup at 28.8 kbps using external AT&T
Paradyne 3800Plus and 3900 Series (V.34bis) modems until the 3600 Series 28.8 kbps dial backup module
(DBM) is available.
Full backup capability is provided. Backup can be initiated automatically from the diagnostic control panel
(DCP), or manually initiated from the DCP or a 6800 Series network management system (NMS).
Restrictions
•Internal dial backup modules (DBMs) are not supported; the DSU ignores an installed DBM.
•External modems receive clocking from the DSU when in Backup mode. The TxClkSource shown in
Table 1 should always be set to DCE. Other selections are not supported.
•Fallback is not supported.
•Only single-port DSU and point-to-point TDM applications are supported (see Customer Applications).
•Since port speeds cannot be lowered for backup, some TDM ports may have to be disabled due to
bandwidth limitations.
•The following diagnostic tests are not supported in external backup: Digital Test (DT), Remote Digital
Loopback (RL), and Bit Error Rate Test (BERT).
•Both the control and tributary DSUs must be equipped with this special ARDIS firmware, which supports
external backup.
Customer Applications
Figure 1 shows the configurations supported by this release; no other configurations are supported.
The basic ARDIS configuration is a point-to-point DSU-TDM operating at 56 kbps over the DDS line, with
Ports 2 and 3 configured for 14.4 kbps and Ports 4 through 6 configured for 2.4 kbps. The first application is
connected to Port 2 and four additional ports are available for application use. An EIA-232 crossover cable
(feature number 4951-035F) is needed to connect the DSU to the modem.
NOTE
If all six ports are needed, enabling Port 1 requires a
V.35-to-EIA-232 converter. Configure Port 1 to operate using the
V.35 interface (for Flex/MUX, set the DTE Port option to V.35 in
TDM Port Configuration Options; when not Flex/MUX, set the DTE
Port option to V.35 in General Configuration Options).

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Figure 1. Point-to-Point Configurations with External V.34 Backup
Configuring the DSU for External Backup
This firmware release supports two modes of external backup so that the modem can:
•Originate a call.
•Answer a call.
To support external backup, changes have been made to the configuration options in the Options (Opts) branch.
To use the external backup feature, use the DSU Configuration option sets: DBM, Diagnostic (Diag) DBM, and
Backup (Bkup).
When using external backup in TDM mode, use MUX Setup for TDM. For the DSU, use the Port Speed (PrtSp)
for DBM to set port speeds.
Table 1 lists the changes to the option sets that have been made to provide external backup capability.

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Table 1
Changes to Manual – Configuration Options
Configuration Option Settings FacC Default FacT Default
DSU Option Set
AggrSwitch Removed N/A N/A
AgSw Timing Removed N/A N/A
DBM Option Set
ExtBU Enab, Disab Enab Enab
AnswExtBU1Enab, Disab Disab Enab
Rate(Kbps)128.8, 24.0, 19.2 28.8 28.8
TxClkSource1DSU only: DCE, Prt12,3
DSU-TDM: DCE, Prt12,3 for DSU,
Prt22,3, Prt32,3, Prt42,3,
Prt52,3, Prt62,3
DCE DCE
Gen Option Set
AnswExtBU Moved to DBM option set — —
Bkup Option Set1
1Does not appear if ExtBU is disabled.
2Does not appear if a 2-Port TDM/Flex is installed.
3Not supported by this release.
External Backup
The DSU uses the DBM option set to configure the DSU for external backup. Once configured for external
backup (ExtBU: Enab) to permit data to be transferred from the DTE to the external modem, the Bckup branch
displays different selections based upon the state of external backup.
When AnswExtBU (Answer External Backup) is disabled, or when both ExtBU and AnswExtBU are enabled, the
Bckup (Backup) branch does not appear on the top-level menu.
•If backup is active – DrBU is the selection.
•If backup is inactive – ExtBU is the selection.
Originating a Call
When configured to originate a call, AnswExtBU (in the DBM option set) is disabled.
To establish a call connection, the DSU raises DSR, which is received by the external modem as a DTR signal via
the crossover cable, signaling the modem to place a call. When the connection is made, the DSU switches data to
the backup line – the alternate port. The DSU then monitors its RTS lead. RTS going high indicates that the call is
completed and the Tries Timeout Timer, set via the TriesTimeOut configuration option, is stopped.
To disconnect a call, the DSU lowers DSR, causing the external modem to disconnect the call. Data is switched
back to the DDS line.

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Answering a Call
When configured to answer a call, AnswExtBU (in the DBM option set) is enabled. The DSU raises DSR and
monitors its DTR lead. When the modem raises DSR, raising DTR and indicating that a call is being established,
the DSU switches data to the backup line – the alternate port. When the external modem’s DSR signal goes low,
indicating that a call is not established, the DSU lowers DSR to disconnect the call and switches the data back to
the DDS line.
NMS Support Considerations
This firmware release is supported by the 6800 Series NMS, but slight variations in configuring the DSU are
required. NMS configuration options are mapped to the following DSU (with external backup capability)
configuration options:
DSU option set:
AggrSwitch – mapped to ExtBU configuration option
DBM option set:
Rate(Kbps) – mapped to different Rate(Kbps) configuration option
AutoAnswer – mapped to AnswExtBU configuration option
DCE Clock Source – mapped to DDS on the NMS
To the NMS, when the DSU is configured for external backup, it appears that a V.32 DBM is installed. The
“V.32 DBM” rate from the NMS will be doubled automatically by a DSU that has this firmware release. The only
valid NMS-entered rates are:
9.6 kbps – converted to 19.2 kbps by the DSU
12.0 kbps – converted to 24.0 kbps by the DSU
14.4 kbps – converted to 28.8 kbps by the DSU
For example, for the DSU to operate at 19.2 kbps for external backup, the NMS operator configures the
“V.32 DBM” to operate at 9.6 kbps. At the DSU, the unit is configured for 19.2 kbps backup.
Configuring the Unit
To configure the DSU from the DCP so that the external modem can originate or answer a backup call:
. Procedure
1. Load the factory-set configuration for either a control (FacC) or tributary (FacT).
2. Go to the DBM option set and verify that ExtBU (External Backup) is enabled, then select Next (F1).
ExtBU determines whether an external modem is being used.
The AnswExtBU (Answer External Backup) configuration option appears.
3. Change the AnswExtBU configuration option setting, if needed, and then select Next (F1). AnswExtBU
determines whether the DSU originates or answers backup.
•To originate a call, set to Disab.
•To answer a call, set to Enab.
The factory setting is Disab for a control DSU and Enab for a tributary. If you change the setting for the
control, you must also change the setting for the tributary; if one originates the call, the other must answer
the call. (Note: If changing the originate-answer configuration, always change external modem
configurations before changing the DSU configurations to prevent the modem from initiating dial backup
prematurely.)
4. Select the DBM Configuration option rate, Rate(Kbps), and then select Next (F1).
5. Press the key until you return to the Edit/Save screen, and Save to Activ.