Operation Manual

Transmission Features
NT/MPRI – 1 Introduction 10
Transmission Features
For optimum utilization of the ISDN bandwidth and to increase trans-
mission performance, the NT/MPRI offers the following functions:
l data compression (in accordance with the V.42bis CAPI standard,
Stac LZS and MPPC)
l header compression for IP and IPX (Van Jacobson TCP/IP header
compression, CIPX header compression)
l channel bundling (in accordance with the CAPI standard as well
as static and dynamic over PPP Multilink)
Reducing and Limiting Connection Charges
Through its intelligent connection management, NT/MPRI makes sure
that the costs for ISDN connections to remote networks are reduced to
a minimum. The following features ensure this:
l The NT/MPRI differentiates between logical and physical ISDN
connections. A logical ISDN connection is produced when the first
physical connection is established over ISDN and the correspond-
ing connection parameters are negotiated. These include the net-
work protocols used, authentication, spoofing mechanisms and
channel bundling.
For the physical ISDN connection one or more B channels are ac-
tually connected, and connection charges are incurred. If no data
are being transmitted on the ISDN line, the NT/MPRI can clear the
physical connection automatically to reduce connection costs.
Depending on the configuration of the corresponding destination,
the logical connection can be maintained in the NT/MPRI so that
the remote site is registered in the network and resources remain
reserved for it there. As soon as data transmission resumes, the
NT/MPRI or the remote site re-establishes the physical connec-
tion.
l The period of time until the physical connection is cleared can be
adapted dynamically to the current charge rates using charge pro-
files. Charge profiles contain information about the various
charge rates for different area codes and times of day. The charge
impulse transmitted on the ISDN line also can be used to control
the clear-down process or to set a charge limit at which the physi-
cal connection is automatically cleared.
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