I did this for two of my clients; one of which uses exchange:
Due to Hurricane Sandy hitting us and Internet connections going up and down without warning (or not coming back up for weeks), I have used a Verizon MiFi 4G LTE connected WIFI to a laptop with ICS configured for all services that I needed and the Laptop's LAN connected to the Failover Port on our SonicWall TZ 200 that I configured for LB/Failover. I was able to send out through Exchange and the client's server was able to recieve as well. It did not seem like any incoming or outgoing ports were blocked, although the client does not use postini, we were able to set our second MX to the DDNS that we configured for the failover connection (you will never get the same IP twice with a 4G connection, they are dynamic) and have not had any issues, it actually worked. The client's primary ISP comes and goes.
We did not use postini however so that is our main difference. In addition, we did not use a wireless bridge we used a laptop but that should not matter. In theory this should work and in practice without postini it has worked for me. Have you tried contacting the verizon wireless team about them blocking ports on your device?
We are using a Verizon Wireless MiFis that are on a no contract month-to-month plan.
- Marc Menzies
Thanks Marc, for the info. The only difference that would matter is that I used an iPad HotSpot connection and you used a MiFi device. Wonder if that had anything to do with it?
I did recently setup a MiFi for a client as their main WAN connection through a TZ215, with their existing SLOW T1 as the failover/secondary, and routed email through the T1 to keep their static IP on email. Unfortunately, they were eating 2GB per day in bandwidth, and we had to shut it down after they reached their 10GB limit as it was not feasible for day-to-day use (although they really enjoyed the 12MB/s up and down speeds of the 4G LTE they had with the MiFi.
Thanks for sharing your experience.
Darryl, in the configuration you set up, your iPad was functioning as a NAT router connected through the transparent wireless bridge to the WAN failover port of your SonicWall. The iPad was also functioning as a DHCP server, and assigned the WAN failover port some private IP address like 172.blah.blah.blah... As a result, no incoming traffic would be able to hit the WAN failover port on your SonicWall without some port forwarding rules in place on the iPad personal hotspot service. Port forwarding is not something that the iOS personal hotspot is able to do.
Of course, I would love for that function to be rolled into personal hotspot, but there are cell carriers involved with decisions that affect how their data plans can be used.