Cisco Cisco IOS Software Release 12.1(3)EC

This feature module describes the Hot-Standby 1+1 Redundancy feature. It includes information on the 
benefits of the new feature, supported platforms, related documents, troubleshooting tips, configuration 
examples, and a detailed command reference.

This document includes the following sections:

The Hot-Standby 1+1 Redundancy feature offers you the ability to provide high system availability 
when you configure a Cisco uBR7200 series universal broadband router to wait in hot-standby mode, 
protecting another Cisco uBR7200 series universal broadband router in case of system failure. The 1+1 
redundancy feature provides three- to five-second automatic system recovery time, thus helping to 
prevent calls from dropping in the system.

It is not uncommon for voice calls in their setup phase to be dropped when a CMTS system 
failure occurs, even with 1+1 redundancy configured on the cable network.

In order for 1+1 redundancy to operate between a Protect CMTS and its Working CMTS peer, the 
configuration files for the two routers must be exactly the same, excluding configuration commands 
specific to 1+1 redundancy. Sections of this feature module describe the necessary differences in 
configuration between a Protect CMTS and its Working CMTS peer.