Operation Manual

Configuring Call Destinations: Fine-Tuning the Settings
47 NT/MPRI – 3 Configuration and Operation of the NT/MPRI: The Basics
In order to keep costs at a minimum for such connections, the NT/MPRI
is configured by default to send RIP/SAP only when changes occur in
the call settings (“Call Destination Configuration / RIP/SAP Updates:
Only On Change”). Do not change this setting.
Static routes to NetWare servers in a remote network also can be de-
fined over ISDN (“Call Destination Configuration / IPX / IPX Routes for
this Call Destination”). This has the advantage of always advertising
the remote server in the local network, even when no logical ISDN con-
nection exists. When data packets are queued for transmission, the
physical ISDN connection is set up automatically.
3.7 Configuring Call Destinations: Fine-Tuning
the Settings
The following section primarily discusses the configuration of call des-
tinations for dial-in connections with regard to cost reduction, security
and network protocols used. Comprehensive information about leased
lines is available in the chapter “Special Settings”.
Reducing Connection Costs
This section discusses the many functions and mechanisms the
NT/MPRI offers to reduce connection costs.
Automatic Disconnect for Idle ISDN Connections
The NT/MPRI distinguishes between logical and physical ISDN connec-
tions. Only for an active physical connection is a B channel in use and
charges incurred.
A physical ISDN connection must not be maintained for the entire peri-
od between establishing a connection and disconnection by the re-
mote site. Compared with analog networks, ISDN offers such fast con-
nection times that idle physical ISDN connections can be cleared and
re-established quickly to reduce costs. In most cases, the transmission
of useful data over ISDN is sporadic at best. Even when the physical
connection is cleared, the logical connection can remain active. As
long as a logical connection is maintained, connection parameters
such as spoofing (see below) remain active.
For an ISDN connection to be maintained logically but cleared physical-
ly, the remote site must be equipped with a router that supports the
concept of a logical connection and can re-establish the physical ISDN
connection as needed.
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