10-3
Cisco IOS XE Integrated Session Border Controller Configuration Guide for the Cisco ASR 1000 Series Aggregation Services Routers
OL-15421-01
Chapter 10 High Availability Support SSO Support
Upon an RPR-based RP switchover event, all SBC calls already established (in a steady state) at the time
of the switchover are lost. Some SBC calls in the process of being established at the time of the
switchover are dropped as gracefully as possible. No new calls can be established briefly after the initial
switchover event. An SBC call reconciliation takes place after an RPR-based RP switchover to ensure
that both RP and Embedded Services Processor (ESP) are in sync.
RPR redundancy can allow for IOS fast software upgrades when ISSU is unavailable. In RPR mode, no
Cisco IOS SBC state information is synchronized to the standby RP. Therefore, all calls are dropped
upon an RPR-based switchover.
Note RPR is supported on the Cisco ASR 1000 Series Routers while RPR+ is not. You can use Stateful
Switchover (SSO) instead of RPR+.
SSO Support
Integrated Session Border Controller support for Stateful Switchover (SSO) allows for stateful IOS
process switchovers where critical state information is synchronized between one Route Processor used
as the active processor and the other RP used as the standby processor. When Cisco IOS is configured
for SSO, the SBC module running on the active IOS process constantly “replicates” its internal state to
its standby peer SBC module on the standby IOS process. In this way, the standby SBC module is kept
in sync with the active IOS process and has all the state information necessary to retain active calls and
resume call processing in the event the active IOS process fails and an SSO occurs.
For information on SSO, see the Cisco IOS High Availability Configuration Guide at
http://www.cisco.com/en/US/products/ps6922/products_installation_and_configuration_guides_list.ht
ml.
ISSU Support
Integrated Session Border Controller supports In-Service Software Upgrade (ISSU) with a redundant RP
or redundant IOS process. The ISSU process allows software to be updated or otherwise modified on a
standby RP or standby IOS process while packet forwarding on the active RP or active IOS process
continues. For the Cisco ASR 1000 Series Routers, ISSU compatibility depends on the software package
being upgraded and the hardware configuration.
See the “High Availability Overview” section in the Cisco ASR 1000 Aggregation Services Router
Software Configuration Guide for more, updated information on ISSU compatibility.
For information on the ISSU process, see the Cisco IOS In Service Software Upgrade and Enhanced Fast
Software Upgrade Process document at:
http://www.cisco.com/en/US/docs/ios/12_2sb/feature/guide/sb_issu.html.