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Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers
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Chapter 10 High Availability Support
Hardware Redundancy
Hardware Redundancy
Integrated Session Border Controller supports use of a redundant or standby Route Processor (RP) and
redundant Embedded Services Processor (ESP) on the Cisco ASR 1006 Router. The Cisco ASR 1006
Router has an ESP as well as an RP for dual hardware redundancy. If the active RP or active ESP
hardware fails, the system performs a switchover to the standby RP or standby ESP. RP and ESP
hardware redundancy support is independent. An RP failure does not require a switchover of the ESP
hardware and an ESP failure does not require an RP switchover.
Hardware redundancy is available only on the Cisco ASR 1006 Router.
Software Redundancy
On the Cisco ASR 1000 Series Routers, Cisco IOS runs as one of many processes within the Cisco IOS
XE operating system. This architecture is different than on traditional Cisco IOS, where all processes
are run within Cisco IOS. The Cisco ASR 1000 Series Router architecture allows for software
redundancy opportunities not available on other Cisco IOS platforms.
Integrated Session Border Controller supports software redundancy by running a standby peer SBC
module within the IOS process that resides in an active RP. If the SBC module fails, then Integ rated SBC
switches over to the standby SBC module in the standby IOS process. The standby IOS process may
reside on the same Route Processor as the active IOS process (Cisco ASR 1002 and Cisco ASR 1004
Routers) or it may be on a redundant, standby RP (Cisco ASR 1006 Router).
On the Cisco ASR 1002 and Cisco ASR 1004 Routers, a standby Cisco IOS process is running on the
same Route Processor as the active Cisco IOS process. In the event of a Cisco IOS failure, the router
switches to the standby Cisco IOS process. No redundant Route Processor or redundant ESP is available
on the Cisco ASR 1002 Series and Cisco ASR 1004 Series Routers.
On the Cisco ASR 1006 Routers, the data border element (DBE) can have a redundant Route Processor
and a redundant ESP. In the event of failure of the active Cisco IOS process, the router switches to the
standby Cisco IOS process, running on a separate standby Route Processor. SBC redundancy at the ESP
level is provided only if a standby, redundant ESP is used. SBC components running on the active ESP
have identical peer components running on the standby ESP . In th is case, if the SBC components running
on the active ESP fail, then a switchover to the backup ESP occurs.
The following types of software redundancy are supported on Integrated Session Border Controller:
• Route Processor Redundancy (RPR)
• Stateful Switchover (SSO)
• In-Service Software Upgrade (ISSU)
Route Processor Redundancy (RPR)
RPR allows you to run with a standby RP without state synchronization. In the event of a fatal error on
the active RP, the system switches to the standby RP, which then completes its initialization. Because all
the state information held by the formerly active RP is lost, the newly active RP has to configure itself
and relearn all the state information.