Configuring Advanced Settings - Cisco 3521 Administrator's Manual

Configuring Gateway Settings
Table 3-8
Field or Check Box
Enable packet handling (may increase call
delay)
Network jitter tolerance
ISDN Options section (For PRI Gateways only)
Request ISDN rollover when less than n B
channels are available
General section
Administrator's Guide for Cisco IPVC 3521 BRI Gateway, Cisco IPVC 3526 PRI Gateway, and Cisco IPVC 3540 PRI Gateway
3-28
Advanced Settings
Chapter 3 Configuring the Cisco IPVC 3500 Series Gateway
Description
Select to configure the maximum rate of jitter
tolerance in the Network jitter tolerance field.
Jitter occurs when IP packets sent at a steady rate
reach their destination at different speeds.
Streams can also split on their way to the gateway
between different routers. This can cause a "later"
packet B to arrive before an "earlier" packet A,
even though A was sent before B.
If you selected the Enable packet handling (may
increase call delay) check box, then enter the
maximum rate of jitter tolerate in milliseconds.
Packet loss occurs when jitter exceeds the
configured rate.
Select to define when the gateway uses the ISDN
rollover feature (Which is defined in advanced
commands. See Configuring Advanced
Commands, page 3-32 for more information).
When the total number of available B channels in
both PRI ports falls below the number specified in
this field, the gateway sends a "busy out" message
to the PSTN switch for each of the remaining B
channels. The switch application "busies out" the
remaining B channels and diverts new calls to
other gateways on the network with greater
available resources. This setting is only active
after you configure the gateway to use a 4ESS PRI
line.
For example, you specify 10 in the Request ISDN
rollover when less than n B channels are
available field and the number of available B
channels falls to 9. The gateway sends a "busy
out" request message to the PSTN switch. The
PSTN switch application routes new calls through
other gateways on the network. When the total
number of available B channels returns to at least
10, the gateway sends a "busy out" cancellation
message to the PSTN switch indicating the
restored ability to receive calls. The PSTN switch
makes the "busied out" lines available and
attempts attempt to route new calls through the
gateway.
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