Cisco WS-X4604-GWY - VoIP Gateway Specifikace stáhnout pdf (Strana 158)

Chapter 6 Multisite WAN with Distributed Call Processing

Dial Plan Considerations

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Cisco IP Telephony Network Design Guide

78-11103-03

Gatekeeper Selection and Redundancy

Fault tolerance for the gatekeeper is very important in the Cisco AVVID network.

Through the use of Hot Standby Router Protocol (HSRP), you can achieve

redundancy for the gatekeepers. Configuring a pair of gatekeepers with HSRP

allows the active gatekeeper to process requests, and, in the event of a failure, the

standby gatekeeper will take over.

Following a failover, the current call state is lost. The standby (now active)

gatekeeper starts with no knowledge of any existing bandwidth or calls currently

in progress. As the calls that were admitted by the failed gatekeeper complete, and

new calls are admitted via the new gatekeeper, call state information is regained.

During the HSRP failover period, gatekeeper functionality is lost. This period is

configurable with the

standby timers command, and, by default, the hello

interval is set to 3 seconds and hold time to 10 seconds.

The use of directory gatekeepers in a hierarchical deployment can support

Cisco CallManager networks with very many clusters. The subject of directory

gatekeepers is beyond the current scope of this document.

Configuring Dialing Restrictions

In a distributed call processing environment, you configure dialing restrictions by

using partitions and calling search spaces. This is very similar to configuring

dialing restrictions in a campus or individual site, as explained in the

“Configuring Dial Plan Groups and Calling Restrictions” section on page 5-14.

Bandwidth Consumption of Dialed Numbers

The bandwidth that is consumed by calls between devices (IP phones and

gateways) can be controlled by setting up regions that dictate codec usage.

Devices are placed in a region that has a particular codec specified for all

intraregion calls and can have other codecs specified for interregion calls.

Regions are assigned to devices using a device pool. The supported codecs

defined in regions are G.711, G.729, and G.723. (G.723 is supported only on the

Cisco IP Phone 12 SP+ and the Cisco IP Phone 30 VIP.)

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Cisco WS-X4604-GWY - VoIP Gateway Specifikace Strana 158