• Virtual Path(VP) between SD-WAN MCN(master control node) and all branches is DEAD. 
• In MCN GUI statistic,
  • Virtual Path detailed VP status shows dead reason is "SILENCE". 
  • MCN--->Branch direction path. NO hearbeat being sent out from "kbps" column with 0 results.
• MCN could receive branch's heartbeat. However MCN doesn't reply heartbeat.
• WAN Link and Interfce is UP.

To match issue behaviors,

-->Check SD-WAN GUI Path statistic by 

1. Go to Monitoring---->Statistics--->Paths(Details)
2. Confirm "Reason" show "SILENCE"
3. Confirm "kbps" show "0.00"

-->Check SD-WAN interface status is UP

1. Go to Configuration---->Applliance Settings--->Network Adapters---Ethernet
2. Confirm all applied interface status UP and Layer2 network para, is negotiated sucessfully with Speed and Duplex field fullfilled correctly.

-->Check SD-WAN ARP statistics by

1. Go to Monitoring---->Statistics--->ARP
2. Confirm defecctive Gateway IP table "State" column show "Reply Pending" instead of expected "READY ACTIVE"

Then, please varify if gateway is still online since it's not answering ARP request.

In some cases, you may need to update SD-WAN configuration with updated gatweay address. Please follow below link:
https://docs.citrix.com/en-us/citrix-sd-wan/current-release/configuration/deploy-mcn-configuration/deploy-configuration-to-branches.html
 

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Problem Cause

This issue is customer environment related, which result SDW unable learn gateway MAC address via interface.