I have just setup a VPN between a Meraki and SonicWALL and am having some issues with traffic flow. I have followed the recommendations in Meraki's documentation but so far have not had full success.
Per Meraki I have enabled Keep Alive on the SonicWALL side which results in the VPN coming up right away but no traffic flows if it originates on the network behind the SonicWALL. Once I initiate traffic from a device behind the Meraki to a device behind the SonicWALL traffic starts to flow in both directions.
A simplified diagram:
______________ ______________ _________ _________________
1) 10.222.25.2 pings 192.168.241.10 and nothing will go through, request timed out
2) 192.168.241.10 pings 10.222.25.2 the ping goes through no problem
3) now 10.222.25.2 is able to ping 192.168.241.10
4) if the VPN breaks for any reason (internet outage) traffic from 10.222.25.2 will not reach 192.168.241.10 until 192.168.241.10 initiates the traffic