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Issue 6 January 2008 271
Connection preserving upgrades for duplex servers
This feature is designed for preserving stable bearer connections for TDM end points and IP
stations during an upgrade of S8700/S8710 duplex servers. TDM and IP connection of H.248
Media Gateways, with the S8700/S8710 being the main call controller will also be preserved.
This feature is supported on all S8700 and S8710 Linux servers running Avaya Communication
Manager 3.0. It is supported on all H.248 Media Gateways and all port networks (including
G650 MG). It will apply on upgrade from Avaya Communication Manager 3.0 to a newer
release, and does not apply on upgrade to Avaya Communication Manager 3.0.
This feature is not call preserving and only preserves connection on stable calls. Connection
preservation will not apply to calls involving H.323 IP trunks; these are H.323 IP calls and SIP
calls. Connection preservation will not apply to IP trunks and ISDN-BRI stations and trunks
using H.248 Media gateways resources.
Inter Gateway Alternate Routing (IGAR)
This feature enables systems with distributed branch offices and distributed call centers an
alternate means of providing bearer connection between port networks and gateways when the
IP-WAN is incapable of carrying the bearer traffic. IGAR may request that bearer connections
be provided by the PSTN under the following conditions:
The number of calls allocated or bandwidth allocated via Call Admission Control – Bandwidth.
Limits (CAC-BL) has been reached.
● VoIP RTP resource exhaustion in a MG/PN is encountered.
● A codec set is not specified between a network region pair.
● Forced redirection between a pair of network regions is configured.
● The number of calls allocated or bandwidth allocated via Call Admission Control –
Bandwidth
● Limits (CAC-BL) has been reached.
IGAR takes advantage of existing public and private-network facilities provisioned in a network
region.
Most trunks in use today can be used for IGAR. Examples of the better trunk facilities for use by
IGAR would be:
● Public or Private ISDN PRI/BRI
● R2MFC
IGAR is the next logical step in providing Quality of Service (QoS) to large distributed
single-server configurations.