Reference documentation and code samples for the Compute Engine v1 API enum BackendServiceConnectionTrackingPolicy.Types.ConnectionPersistenceOnUnhealthyBackends.
Specifies connection persistence when backends are unhealthy. The default value is DEFAULT_FOR_PROTOCOL. If set to DEFAULT_FOR_PROTOCOL, the existing connections persist on unhealthy backends only for connection-oriented protocols (TCP and SCTP) and only if the Tracking Mode is PER_CONNECTION (default tracking mode) or the Session Affinity is configured for 5-tuple. They do not persist for UDP. If set to NEVER_PERSIST, after a backend becomes unhealthy, the existing connections on the unhealthy backend are never persisted on the unhealthy backend. They are always diverted to newly selected healthy backends (unless all backends are unhealthy). If set to ALWAYS_PERSIST, existing connections always persist on unhealthy backends regardless of protocol and session affinity. It is generally not recommended to use this mode overriding the default. For more details, see Connection Persistence for Network Load Balancing and Connection Persistence for Internal TCP/UDP Load Balancing.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-08 UTC."],[[["\u003cp\u003eThis page provides reference documentation for the \u003ccode\u003eBackendServiceConnectionTrackingPolicy.Types.ConnectionPersistenceOnUnhealthyBackends\u003c/code\u003e enum within the Google Cloud Compute Engine v1 API.\u003c/p\u003e\n"],["\u003cp\u003eThe latest version documented is 3.6.0, with versions ranging back to 1.0.0 available for review.\u003c/p\u003e\n"],["\u003cp\u003eThis enum specifies how connections are handled when backends become unhealthy, offering options for connection persistence, defaulting to \u003ccode\u003eDEFAULT_FOR_PROTOCOL\u003c/code\u003e for connection-oriented protocols.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eConnectionPersistenceOnUnhealthyBackends\u003c/code\u003e enum has four fields: \u003ccode\u003eAlwaysPersist\u003c/code\u003e, \u003ccode\u003eDefaultForProtocol\u003c/code\u003e, \u003ccode\u003eNeverPersist\u003c/code\u003e, and \u003ccode\u003eUndefinedConnectionPersistenceOnUnhealthyBackends\u003c/code\u003e, each representing different persistence behaviors.\u003c/p\u003e\n"],["\u003cp\u003eThe default behavior \u003ccode\u003eDEFAULT_FOR_PROTOCOL\u003c/code\u003e, causes existing connections to persist on unhealthy backends for TCP and SCTP protocols under specific conditions.\u003c/p\u003e\n"]]],[],null,[]]
