System Management
7210 SAS M, T, X, R6 Basic System Configuration Guide Page 205
High Availability
NOTE: High availability with control plane redundancy is an option available for use only on 
7210 SAS-R6. Control plane redundancy option is not available on 7210 SAS-X, 7210 SAS-M 
and 7210 SAS-T. These platforms support only component redundancy as described below. 
This section discusses the high availability (HA) routing options and features available to service 
providers that help diminish vulnerability at the network or service provider edge and alleviate the 
effect of a lengthy outage on IP networks.
High availability is an important feature in service provider routing systems. High availability is 
gaining momentum due to the unprecedented growth of IP services and applications in service 
provider networks driven by the demand from the enterprise and residential communities. 
Downtime can be very costly, and, in addition to lost revenue, customer information and business-
critical communications can be lost. High availability is the combination of continuous uptime 
over long periods (Mean Time Between Failures (MTBF)) and the speed at which failover or 
recovery occurs (Mean Time To Repair (MTTR). 
The popularity of high availability routing is evident at the network or service provider edge 
where thousands of connections are hosted and rerouting options around a failed piece of 
equipment can often be limiting. Or, a single access link exists to a customer because of additional 
costs for redundant links. As service providers converge business-critical services such as real-
time voice (VoIP), video, and VPN applications over their IP networks, high availability becomes 
much more stringent compared to the requirements for best-effort data. Network and service 
availability become critical aspects when offering advanced IP services which dictates that IP 
routers that are used to construct the foundations of these networks be resilient to component and 
software outages. 
HA Features
As more and more critical commercial applications move onto the IP networks, providing high 
availability services becomes increasingly important. This section describes high availability 
features for devices. 
• Redundancy on page 206
→ Software Redundancy on page 206
→ Configuration Redundancy on page 206
→ Component Redundancy on page 207
→ Service Redundancy on page 207
→ Accounting Configuration Redundancy on page 207