Operation Manual

Introduction to NetWare MultiProtocol Router for ISDN 3.1 37
apply on the network level to decrease the possibility of unnecessary
packets to be generated for a remote server/service.
♦♦ Frequent call set-up due to ISDN security features and "train-
ing" time required for other features to get active
Third, due to the fact that all ISDN Interface and ISDN Call Destina-
tion Configurations are always negotiated first with the respective
remote site during initial logical ISDN connection set-up, Security
Call-Back is for example consequently performed each time a remote
site initially dials up the respective ISDN interface on your router to
set up a connection, the B channel is cleared and the remote site is
dialed back, resulting in charges accruing at your site for the call
back. Besides, some features require a training time to get active. For
example Recall Request does not apply for initial call set-up. Thus,
when your router initially dials up a remote site and you configured
Recall Request to have the remote site dial you back and assume the
charges for the connection, the remote site will not do so for this first
incoming call from your site but only for all subsequent incoming
calls from your site. Other features that require "training time" and
are only advantageous if a logical ISDN connection to a remote site
is up are Self-Learning Inactivity Timeout or SPX Spoofing.
♦♦ Two configurations that may increase the possibility of
critical situations
First, the more call destinations you configure to different remote
sites over a single ISDN interface without taking care about the
network and ISDN-specific behavior, the higher the possibility that a
networking process gets interrupted because the data cannot be
transfered to all sites and the higher the possibility of frequent call
set-ups. Second, setting Disconnect Timeout to the same value as
Inactivity Timeout has the advantage of a high ISDN interface
availability for multiple connections, but without taking care about
the network and ISDN-specific behavior, the chance of frequent call
set-ups increases as well, since all the ISDN-specific features espe-
cially implemented with NetWare MultiProtocol Router for ISDN to
keep ISDN lines physically down, such as Watchdog Spoofing, SPX
Spoofing and IPX Message Filter, can only be active for a very short
time frame or cannot be activated at all.
The NetWare MultiProtocol Router for ISDN supports both, static
and dynamic ISDN interface usage for classic WAN set-up and for
Introduc.pm6 27.05.97, 21:0337