Shared Gateway over DMVPN

[Daryl Clark]

We are looking to deploy a DMVPN solution for 20 remote devices.  At each remote site there will only be a single endpoint connected and thus only a single IP needed.  I am wondering if it is possible for all sites to share the same subnet with a common gateway at the hub location or if I will need to create a /30 at each site and advertise those subents back into my LAN.

[Giuseppe Larosa]

Hello Daryl,

you will need an IP subnet for each remote site as the target of DMVPN is to interconnect LANs over an arbitrary IP network with an emulated flat network in the middle ( the multipoint GRE performs this task).

It is a L3 service so you cannot have a single gateway in hub and a single IP subnet that spans over the remote sites.

In choicing the IP subnets I would use  a less specific IP subnet as needs may easily change over time, what if a user one day is in another office?

Using a /28 should be a good choice.

Hope to help

Giuseppe