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
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
Service
Service PIC Failure
Routing 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.
