Hello all,   Our HQ and primary DC is in NY.  The secondary DC which is partially a DR site but also has some active services is in NC.  We have branches in NY, NC, and SC connected to our DCs through metro-e connections.  Currently, with our ISR routers, NY branches connect to the NY DC, while NC and SC connect to the NC DC.  All branches also have cellular gateways as a backup connection.    Below is how i currently have things hooked up in my lab phase. The Metro-E is any to any so the 2 DCs can potentially communicate through it and branches can potentially communicate directly with both DCs.  I say potentially because in our current build pre-Meraki, that's not how it's set up.  You'll notice there's 2 more connections between DCs but my goal would be for everything branch related to stay on Metro-E until they reach the DC that whatever service is at.  Meaning, I would prefer a NC branch doesn't send traffic to the NC DC to then ride the p2p to NY and instead send traffic to the NY Hub, unless the NY Hub is down, then it would come into NC and traverse the datacenter p2p.   Note:  We currently plan for traffic to stay on Metro-E unless a branch needs to connect through their Cellular backup.  The MX105's are getting internet access through the default gateway on the L3 switch. I believe my main questions at this point are: Is it better to be using One-arm Concentrator or Routed mode for this?  I started with Routed mode and then just switched to VPNC after reading about dc-dc failovers.  Now i'm believing I don't actually want DC-DC failover because I don't need any local networks to failover between DCs.  I just need traffic to reroute.  Would either method have limitations in my scenario? Note:  even if i were doing Routed mode, i still need the L3 switch in NY due to the HA pair of MX105s.    Why would my cellular backups at the branches be able to form a VPN with the HUBs in routed mode but not VPNC?  Something to do w/ auto-NAT maybe?   Is it going to be possible to have branches form connections to both HUBs and send traffic to each?  Can the 2 HUBs send traffic to each other which essentially means there's a third connection between my datacenters? ... View more