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Maintenance and Failover in the Packet Gateway Overview

By providing redundancy for both the Routing Engine and the service PICs, the packet gateway high-availability (HA) architecture allows for a multilevel redundant solution. This solution ensures service and call continuity, which is necessity for VoIP services.

Figure 24 shows the packet gateway HA architecture.

Figure 24: Packet Gateway HA Architecture

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Table 15 indicates how service PIC failure and Routing Engine failure affect different types of services.

Table 15: How Service PIC and Router Engine Failures Affect Service and Call Continuity

ServiceService PIC FailureRouting Engine Failure

Stable H.248 contexts

Call continuity—All calls are lost.

Service continuity—Provided when the backup service PIC is available.

Call continuity—All existing calls are maintained through the failure

Service continuity—New calls and session can be established when the backup Routing Engine takes control.

H.248 contexts are modified

Call continuity—All existing call states are lost.

Service continuity—Calls and sessions that are in a Setup state (gates and terminations not fully defined) are lost

Call continuity—All existing call states are lost.

Service continuity—Calls and sessions that are in a Setup state are lost.

Connection to the PGC

Call continuity—All calls are lost.

Service continuity—Provided when the backup service PIC is available.

Call continuity—No calls are lost.

Service continuity—Provided when the backup Routing Engine takes control.


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