The diagnostic code specifies the local system's reason for the last change in session state. This allows remote systems to determine the reason that the previous session failed, for example. These diagnostic codes are specified in section 4.1 of RFC5880
[[["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complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-08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\u003eThe latest version of the \u003ccode\u003eGoogle.Cloud.Compute.V1.BfdPacket.Types.Diagnostic\u003c/code\u003e is 3.6.0, and the page provides links to various versions ranging from 1.0.0 to 3.6.0.\u003c/p\u003e\n"],["\u003cp\u003eThe content describes the \u003ccode\u003eDiagnostic\u003c/code\u003e enum within the \u003ccode\u003eGoogle.Cloud.Compute.V1\u003c/code\u003e namespace, found in the \u003ccode\u003eGoogle.Cloud.Compute.V1.dll\u003c/code\u003e assembly.\u003c/p\u003e\n"],["\u003cp\u003eThe \u003ccode\u003eDiagnostic\u003c/code\u003e enum provides diagnostic codes that explain the local system's reasons for session state changes, as detailed in RFC5880 section 4.1.\u003c/p\u003e\n"],["\u003cp\u003eThe enum has eleven fields including \u003ccode\u003eAdministrativelyDown\u003c/code\u003e, \u003ccode\u003eConcatenatedPathDown\u003c/code\u003e, \u003ccode\u003eControlDetectionTimeExpired\u003c/code\u003e, \u003ccode\u003eEchoFunctionFailed\u003c/code\u003e, \u003ccode\u003eForwardingPlaneReset\u003c/code\u003e, \u003ccode\u003eNeighborSignaledSessionDown\u003c/code\u003e, \u003ccode\u003eNoDiagnostic\u003c/code\u003e, \u003ccode\u003ePathDown\u003c/code\u003e, \u003ccode\u003eReverseConcatenatedPathDown\u003c/code\u003e, \u003ccode\u003eUndefinedDiagnostic\u003c/code\u003e, and \u003ccode\u003eUnspecified\u003c/code\u003e.\u003c/p\u003e\n"]]],[],null,[]]
