Operation Manual

204 NetWare MultiProtocol Router for ISDN 3.1 Installation and ISDN Configuration Guide
Situation
Router A:
Call destination
for Router B: Inactivity Timeout = 19
Disconnect Timeout =30
Consequence
The physical connection is cleared after 19 seconds of inactivity on the link. All B channels are
disestablished. When the Disconnect Timeout expires 11 seconds later, one B channel is again switched
through, i.e. the physical connection is established for a short time to notify the remote site that the logi-
cal connection is now cleared. Thus, one charge unit is wasted.
Timeout Mechanisms and Spoofing/Filtering
Spoofing and filter mechanisms work only when there is a logical
network connection between two sites. For dynamic interface usage,
consider the following critical situation:
Situation
Router A:
Call destination
for Router B: Inactivity Timeout = Disconnect Timeout
Router A and Router B:
Spoofing and filter mechanisms: Enabled
Consequence
Filter and spoofing mechanisms in NetWare MultiProtocol Router for ISDN work only when a logical con-
nection between two sites exists. When Inactivity Timeout and Disconnect Timeout are set to the same
value, both, the physical and the logical connection are cleared when the link has been idle for the speci-
fied period. Thus, spoofing and filtering is only active during this period. After that, spoofing and filtering
is terminated, i.e. Watchdog packets, SPX keep-alive-packets etc. are anew transmitted to the remote
site(s) and are not spoofed on the NetWare MultiProtocol Router for ISDN. For dynamic interface usage,
where the physical connection is always set up when data packets are to be transferred, this can lead to
a high number of call set-ups and, consequently, charge units.
Configur.pm6 27.05.97, 12:33204