Session down and disconnect event in BGP domain.

Products

• VMware Smart Assurance

Issue/Introduction

What is the logic to determine a BGP session down and disconnect event?

Environment

SMARTS-10.1.x

Resolution

Smarts determines BGP session events (Down and Disconnected) using the following logic:

If the session is disconnected and if the peer is not missing, the Down and Disconnected events will be generated.
If the session is disconnected and if the peer is missing then the Disconnected and PeerMissing events will be generated.

This is the code that Smarts uses to determine the difference between Down - Disconnected and PeerMissing events.

computed attribute boolean IsIBGPPeerMissing
    "True if peer system is missing."
    = (IsSessionDisconnected &&
       !IsBGPPeerAdminDown &&
       !IsEBGP &&
       (|PeerSystem| == 0));

event Disconnected
    "One or more endpoints of this link do not have ESTABLISHED connections."
    loss(0.0001)
    = !IsFlapping && SessionDisconnectedAttribute; 
    export Disconnected;

refine symptom LocalSymptoms
    = Disconnected,
      PrefixThresholdCrossed 0.1,
      Disconnected explains,
      PrefixThresholdCrossed explains,
      SessionGroupImpactedSymptom explains;

  problem Down
    "This BGP link between neighboring endpoints is down."
    => LocalSymptoms if !IsIBGPPeerMissing,
       LocalSymptoms explains if !IsIBGPPeerMissing;
  export Down;