Multiple continental DMVPN HUB and spoke topology

[dev.puniya]

Hello There,

I am trying to explore an option of setting up multiple continental DMVPN HUBs and each spoke router in that continent will talk to a local DMVPN HUb. However, I am skeptical about the following - 

How will be the HUB-to-HUB communication? 

Will spoke still be able to set up a direct phase 3 communication, even though the hub is regional?

Or instead of I use only 4 routers in the same region and make all 4 HUBs for the rest of the spoke site. 

Do I need to be aware of any special things which might over complicated the topology and/or failure scenarios?

What are the major drawbacks of seeing multiple continental HUB vs regional hubs?

Thank you!

[MHM Cisco World]

now you want active/active Hub 
this need to make both Hub advertise the LAN to Spoke 
https://networklessons.com/cisco/ccie-enterprise-infrastructure/dmvpn-dual-hub-dual-cloud

if you want primary/backup Hub
then make backup hub as spoke to primary hub 

https://networklessons.com/cisco/ccie-enterprise-infrastructure/dmvpn-dual-hub-single-cloud

[dev.puniya]

Hi MHM,

It is not just a typical HUB and SPOKE topology, currently, I have active/passive tunnels but this is a little different than what you just described. Thank you for your response. 

[Rob Ingram]

@dev.puniya sounds like you are looking for a hierarchical DMVPN design, with a Central bub(s) and regional hubs, this allows spoke-to-spoke tunnels to be built between any spokes within the DMVPN network, whether they are in the same region or not.

This guide provides more information, describing the design and packet flow. https://www.cisco.com/c/en/us/support/docs/security/dynamic-multipoint-vpn-dmvpn/211292-Configure-Phase-3-Hierarchical-DMVPN-wit.html

[MHM Cisco World]

draw topology can help us to give you right design