Cisco ASR1006 Configuration Guide - Page 232

IPsec Failover High Availability Overview On the Cisco ASR 1000 Series Router, SSO can also be used to enable a second IOS process on a single RP for a Cisco ASR 1002 or 1004 Router. See the "Second IOS Process on a Cisco ASR 1002 or 1004 Router" section on page 4 for additional information on the second IOS process. It is important to note that in most cases, SSO requires less downtime for switchover and upgrades than RPR. RPR should only be used when there is a compelling reason to not use SSO. For additional information on NSF/SSO, see the Cisco Nonstop Forwarding document. SSO-Aware Protocol and Applications SSO-supported line protocols and applications must be SSO-aware. A feature or protocol is SSO-aware if it maintains, either partially or completely, undisturbed operation through an RP switchover. State information for SSO-aware protocols and applications is synchronized from active to standby to achieve stateful switchover for those protocols and applications. The dynamically created state of SSO-unaware protocols and applications is lost on switchover and must be reinitialized and restarted on switchover. To see which protocols are SSO-aware on your router, use the following commands show redundancy client or show redundancy history. IPsec Failover IPSec failover is a feature that increases the total uptime (or availability) of a customer's IPSec network. Traditionally, this is accomplished by employing a redundant (standby) router in addition to the original (active) router. If the active router becomes unavailable for any reason, the standby router takes over the processing of IKE and IPSec. IPSec failover falls into two categories: stateless failover and stateful failover. The IPsec on the Cisco ASR 1000 Series Router supports only stateless failover. Stateless failover uses protocols such as the Hot Standby Router Protocol (HSRP) to provide primary to secondary cutover and also allows the active and standby VPN gateways to share a common virtual IP address. Bidirectional Forwarding Detection Bidirectional Forwarding Detection (BFD) is a detection protocol designed to provide fast forwarding path failure detection times for all media types, encapsulations, topologies, and routing protocols. In addition to fast forwarding path failure detection, BFD provides a consistent failure detection method for network administrators. Because the network administrator can use BFD to detect forwarding path failures at a uniform rate rather than the variable rates for different routing protocol hello mechanisms, network profiling and planning is easier, and reconvergence time is consistent and predictable. On the Cisco ASR 1000 Series Routers, BFD for IPv4 Static Routes and BFD for BGP are supported. For more information on BFD, see the Bidirectional Forwarding Detection document. Cisco ASR 1000 Series Aggregation Services Routers Software Configuration Guide 6