An empty AS Path typically indicates that the route is not learned via BGP (Border Gateway Protocol) but is instead manually configured, may this thread help you
How to create an effective route for Virtual HUB with type VPN_S2S_Gateway with out AS PATH field
Shaked Eyal
41
Reputation points
Hi,
We are trying to recreate a situation we saw previously on our system, which is inside the effective routes of a Virutual HUB with Azure Firewall and Routing Intent enabled.
The case was an effective route in the default
routing table we had a route with a Next hop Type
equal to VPN_S2S_Gateway,
but the AS Path
was empty.
What are the conditions for this situation?