Web OS 10.0 Application GuideChapter 11: High Availability n 283212777-A, February 2002Stateful Failover of Layer 4 and Layer 7Persistent SessionsWeb OS provides stateful failover of content-intelligent persistent session state and Layer 7persistent session state. This includes the following: SSL session state HTTP cookie state Layer 4 persistent FTP session stateProviding stateful failover enables network administrators to mirror their Layer 7 and Layer 4persistent transactional state on the peer switch.N OTE – Stateful failover does not synchronize all sessions, except persistent sessions. Makesure Direct Access Mode (DAM) is enabled when you configure stateful failover for Layer 7persistency (for example: SSL session ID persistence-based server load balancing, URL andcookie-based server load balancing).To provide stateful failover, the state of the connection and session table must be sharedbetween the switches in high-availability configurations. With Virtual Matrix Architecture(VMA) enabled, all URL and cookie-parsing information is stored in the session table on port9. Sharing this information between switches is necessary to ensure the persistent session goesback to the same server.N OTE – Stateful failover is only supported in active-standby mode with VMA enabled.
