White Paper Abstract:
ISSU, available on the Cisco Catalyst 4500 E-Series, allows customers to virtually eliminate planned outages for full feature software upgrades. It provides the means to upgrade or, if needed, downgrade the Cisco IOS® Software in a redundant Cisco Catalyst 4500 E-Series system without incurring a service outage. ISSU adds additional functionality to the Cisco Catalyst 4500 E-Series high-availability capabilities provided by Stateful Switchover (SSO) and Nonstop Forwarding (NSF), discussed elsewhere in this paper.