Overview and configuration

First of all, what is the "overlay stickiness"? It applies to Spoke-to-Spoke traffic only. It instructs the Hub to prefer staying within the overlay selected by the originating Spoke. And it is typically configured using policy routes, such as:

config router policy
  edit 1
    set input-device EDGE_ISP1
    set output-device EDGE_ISP1
  next
  edit 2
    set input-device EDGE_MPLS
    set output-device EDGE_MPLS
  next
end

As mentioned earlier, the Jinja Templates generate these simple policy routes on the Hubs by default, for each defined overlay. This functionality can be disabled, by adding the following optional parameter to the Project Template:

{% set overlay_stickiness = false %}

To understand when it makes sense to disable it and when it is better to keep the default behavior, let us go back to the two types of the topologies and examine them one by one:

• Topologies with segregated transports

• Topologies with interconnected transports