Bidirectional Forwarding and Detection Health Check over Virtual Machine Interfaces
Contrail Networking supports BFD-based health checks for VMIs.
Health check for VMIs is already supported as poll-based checks with ping and curl commands. When enabled, these health checks run periodically, once every few seconds. Consequently, failure detection times can be quite large, always in seconds.
Health checks based on the BFD protocol provide failure detection and recovery in sub-second intervals, because applications are notified immediately upon BFD session state changes.
If BFD-based health check is configured, whenever a BFD session status is detected as Up or Down by the health-checker, corresponding logs are generated.
Logging is enabled in the contrail-vrouter-agent.conf file with the log severity level SYS_NOTICE.
You can view the log file in the location
Snippet of sample log message related to BFD session events
2019-02-26 Tue 14:38:49:417.479 SYS_NOTICE BFD session Down interface: test-bfd-hc-vmi.st2 vrf: default-domain:admin:VN.hc.st2:VN.hc.st2 2019-02-26 Tue 14:38:49:479.733 PST SYS_NOTICE BFD session Up interface: test-bfd-hc-vmi.st2 vrf: default-domain:admin:VN.hc.st2:VN.hc.st2