Difference between Link Down Alert Notification and Link Dead Event

Products

• VMware VeloCloud SD-WAN
• VMware SD-WAN by VeloCloud

Issue/Introduction

The article explains the difference between Link Down Alert Notification and Link Dead Event

Environment

VMware VeloCloud SD-WAN all supported releases.

Resolution

Link Down Alert

 

Edge uploads link stats to VCO, VCO based on incoming link stats to drive the fact if link is alive or not. If link stats tell VCO the link is disconnected. Then Link Down alert is triggered. If situation does not change until the delay timer is reached, notification will be sent.

Link Down Alert is decided and generated by VCO.

 

VCO backend log

2024-11-08T05:36:45.020Z - info: [process.edge-monitor.173101922.34227] [29057] link [GE5/172.16.5.10/01c215ec-6941-4eb0-9694-3aa7060369cb] event driven state change from [STABLE] to [UNSTABLE]
2024-11-08T05:37:15.020Z - info: [process.edge-monitor.173102274.42979] [30438] link [GE5/172.16.5.10/01c215ec-6941-4eb0-9694-3aa7060369cb] event driven state change from [UNSTABLE] to [DISCONNECTED]
2024-11-08T05:37:15.024Z - info: [process.edge-monitor.173102274.42979] [30438] link trigger inserted {"enterpriseAlertConfigurationId":3,"enterpriseId":1,"linkId":16,"holdingEdgeSerialNumber":"","linkName":"GE5_Private (GE5)","edgeId":5,"edgeName":"b5-edge1","state":"PENDING","stateSetTime":"2024-11-08T05:37:15.022Z","lastContact":"2024-11-08T05:35:40.000Z","triggerTime":"2024-11-08T05:37:15.022Z","timezone":"Asia/Tokyo","locale":"en-US","remainingNotifications":1,"nextNotificationTime":"2024-11-08T05:40:15.022Z","name":"LINK_DOWN","type":"LINK_DOWN","firstNotificationSeconds":180,"maxNotifications":1,"notificationIntervalSeconds":300,"resetIntervalSeconds":3600}

 

VCO Monitor Alerts Page

 

Link Dead event

 

If all paths on a WAN link are dead, then the WAN link is dead, the Link Dead event is triggered and edge informs VCO via management heartbeat.

Link Dead Event is decided and generated by edge. 

 

edged.log

2024-11-08T03:40:56.415 |1499867| SEVERE	[LINKFSM] run_link_fsm:443 Link GE3 old state STABLE is now in QUIET state
2024-11-08T03:41:02.728 |1499867| SEVERE	[LINKFSM] run_link_fsm:443 Link GE3 old state QUIET is now in INITIAL state
2024-11-08T03:41:02.728 |1499867| SEVERE	[LINKFSM] send_network_event:432 Link GE3 is now DEAD
2024-11-08T03:41:19.516 |1499867| SEVERE	[LINKFSM] run_link_fsm:443 Link GE3 old state INITIAL is now in UNSTABLE state
2024-11-08T03:41:19.516 |1499867| SEVERE	[LINKFSM] send_network_event:432 Link GE3 is no longer DEAD
2024-11-08T03:41:19.541 |1499867| SEVERE	[LINKFSM] run_link_fsm:443 Link GE3 old state UNSTABLE is now in STABLE state

 

mgd.log

2024-11-08T03:41:02.729 INFO    [server (19430:MgdServer:19504)] Received event LINK_DEAD on link 'GE3' from edged
2024-11-08T03:41:28.860 DEBUG   [heartbeat (19430:Heartbeat:19510)] Heartbeat: Config: WAN:1730874928541,QOS:1730874928541,firewall:1730874928541,controlPlane:1730874928542,analyticsSettings:0,properties:1728446855000,managementPlane:1714369699924,metaData:0,imageUpdate:1717656366730,deviceSettings:1730874928541,atpMetadata:0, Events: LINK_DEAD(Link GE3 is now DEAD),LINK_ALIVE(Link GE3 is no longer DEAD)

 

VCO Monitor Events Page