GRE CSS tunnels configured over backup links

Products

• VMware VeloCloud SD-WAN

Issue/Introduction

For GRE CSS tunnel setup over backup link, the GRE CSS tunnel will only come up if the backup link is backup active.

But if the link is backup Idle the GRE CSS tunnel will remain down.

Environment

Customer trying to build GRE CSS tunnels using a backup WAN link.

Cause

This is an expected behavior of GRE.

Resolution

A link as backup idle will not bring the GRE CSS tunnel up, only backup or hot standby can do under below condition.

"A backup/hot-standby link will only be used if the number of available active links is less than the number of minimum active links configured"