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Route Switch Processor (RSP8) Installation and Configuration Guide
OL-4920-02
Enabling High Availability Features
Youcan manually synchronize configurationfiles and ROM monitor environment variables on the active
and the standby RSPs using the following command in privileged EXEC configuration mode:
Caution When you install a second RSP for the firsttime, you must immediately configure it using the slave
sync config command. This ensures that the new standby RSP is configured consistently with the
activeRSP. Failure to do so might result in an unconfiguredstandby RSP taking control of the router
when the active RSP fails, rendering the network inoperable.
The slave sync config command is also a useful tool for more advanced implementation methods not
discussed in this document. Refer to the Cisco IOS Configuration Fundamentals Configuration Guide
and the Cisco IOS Configuration Fundamentals Command Reference publications, which are available
on the Documentation CD-ROM, online at Cisco.com, or as printed documents.
Enabling High Availability Features
This section discusses the following topics:
•High Availability Feature Overview, page41
•Hardware and Software Prerequisites, page 43
•Installation Procedures, page 43
•RPR, RPR+, SSO, and FSU Troubleshooting Tips, page63
High availability (HA), an alternative to the default high system availability (HSA) feature, is a series
offeatures that minimizes system downtime through a “warm standby.”Warm standby allows the system
toswitch over to a standby RSP preloaded with a Cisco IOS image in 30 seconds to 5 minutes, depending
on the feature. For more information on high service availability (HSA), the system default program,
referto the “Configuring High System Availability” section on page 25. Like HSA, HA is supported on
theCisco 7507, Cisco 7507-MX, Cisco 7513, and Cisco 7513-MX routers with two RSP8s, or with one
RSP8 and one RSP16.
A router configured for HA has two RSPs, an active RSP and a standby RSP. The active RSP controls
all functions of the router, and the standby RSP monitors the active for failure.

High Availability Feature Overview

HA features include:
•SingleLine Card Reload (SLCR)—Speeds recovery of a failed router by reloading a failed line card
without reloading other line cards on the network backplane. SLCR isolates the fault to a single
Versatile Interface Processor (VIP2 or VIP4) or Legacy interface processor card, and accelerates
recovery time by reloading only the faulty VIP or Legacy interface processor card. Physical lines
and routing protocols on the other line cards of the network backplane remain active. The system
continues forwarding packets with minimal interruptions.
Command Purpose
Router# slave sync config Manually synchronizes active and standby configuration
files.