16
CSU/DSU MS DBU
Modem Module allows switched backup over the public switched telephone
network (PSTN). The ISDN Module is compatible with National ISDN and
supports a U-interface to the Basic Rate ISDN.
1.2 DDS Operation
DDS is a nationwide service that allows interconnection and transport of data at
speeds up to 64 kbps. The local exchange carriers provide the local loop service to
DDS customers and may provide data for routing Inter-LATA to an interexchange
carrier. In DDS mode, the CSU/DSU MS DBU supports 2.4-kbps to 64-kbps DDS
service rates yielding DTE rates of 2.4, 4.8, 9.6, 19.2, 38.4 (sync or async), 56 kbps,
and 64 kbps. An additional rate of 57.6 is available in asynchronous mode. The
unit can be configured to run slower DTE rates (async or sync) over the 56 or 64
kbps service.
1.3 Switched 56 Operation
Dial-up, 4-wire Switched 56 DDS allows customers to pay for data connection only
for the time the unit is active. The regional operating companies provide the 4-wire
local loop service to SW56 customers. The CSU/DSU MS DBU supports DTE rates
of 2.4, 4.8, 9.6, 19.2, 38.4, and 56 kbps (synchronous) and 2.4, 4.8, 9.6, 19.2, 38.4,
and 57.6 kbps (asynchronous).
1.4 SNMP
The term SNMP (Simple Network-Management Protocol) broadly refers to the
message protocols used to exchange information between the network and the
managed devices, as well as to the structure of network-management databases.
SNMP has three basic components:
N
ETWORK
M
ANAGER
Control program that collects, controls, and presents data pertinent to the
operation of the network devices. It resides on a network-management station.
A
GENT
Control program that resides in each network device connected. This program
responds to queries and commands from the network manager and returns
requested information or invokes configuration changes initiated by the manager.