Verilink DIU 2130 (880-503297-001) Product Manual - Manual (Page 49)

Verilink 5-1
Chapter
5
T1 Dial Backup Option Overview
The T1 Dial Backup Option automatically switches a failed T1 or
fractional T1 (FT1) to a usage-measured dial-up circuit if a
dedicated T1 circuit or dedicated 56K circuit becomes unusable.
The dial backup circuit can be selected from the following
alternatives:
• Switched 56 (SW56)
SW56 is a switched carrier service providing 56 kbit/s dial-up
lines. It charges customers for data connection only when the
interface unit is active.
• Analog modem service
• Integrated Services Digital Network — Basic Rate Interface (ISDN
BRI) service
The backed up circuit can be n × 56 or n × 64 kbit/s. The
DIU 2130/DBU automatically reduces clock rates as necessary.
Figure 1 illustrates an application in which a circuit composed of a
56 kbit/s circuit and a T1 circuit. The circuit is backed up by a
Verilink AS2000 at a central site and by a 56K Dial Backup Unit at
the far-end.
Figure 1 Example Application of the T1 Dial Backup Option in an AS2000 Node
This T1 Dial Backup Option is an EPROM upgrade or download
upgrade to the Verilink Data Interface Unit (DIU) 2130 plug-in
module. The upgraded plug-in module is designated as the
DIU 2130/DBU.
The option can use the Verilink ConnecT 56K Data Service Unit
(DSU) as the interface to the backup circuit. Third party devices
with Data Terminal Ready (DTR) dialing can also be used.
ConnecT
Central
Office
SW56
V.35
56 kbit/s
56K DSU
Dedicated 56 kbit/s
SW56
Router
DIU
NCC*
202
2130/DBU
V.35
Dedicated T1
V.35
56 kbit/
56 kbit/s
56 kbit/s
DBU
AM2000
PC-compatible
Router
* Node Controller and Channel Service Unit