We’ve had a number of interesting WAN designs the past few months where our clients are considering 4G as a failover method for remote site redundancy. This is considered a viable alternative when there is concern about the remote site being completely cut off from the outside world through hard line connections. 

Generally this concern comes from the possibility that fiber and copper lines are cut at the street close enough to the site to cause all connectivity to be severed.  Most remote sites do not have more than one path into the building. Even if you have an alternate carrier, such as a second internet connection from another provider, it still comes in through the same path.  If that path is severed, then all connections are down. This is where an over-the-air solution becomes valuable.  

Let’s consider the options. 

4G

If you can get decent data plans from your carrier, 4G has plenty of bandwidth in most cases to handle a failover situation. You’ll want to make sure you have adequate signal and, if needed, extend the antennas or locate the router to a location where good signal exists. If you are using a Cisco router, you can add a 4G card.  From there, it’s just a matter of configuration to allow the router to use this connection in a failover situation. 

Another option for 4G is through the use of the Meraki Wireless WAN, or Cellular Gateway.  This uses a cloud-based device to establish site connectivity over a wireless carrier network.  The wireless gateway is installed and connected to the network and is controlled via the Meraki cloud dashboard—an elegant way to establish site-to-site failover.  

Wireless Internet

The other option is through plain wireless internet. There are many wireless internet providers today, and there is very likely one within the range of the site that needs failover.  The wireless ISP will usually provide their own wireless gateway that will have an ethernet hand-off you can connect to your router. The router will then make the decision of when to use this connection.

Or, if you have SDWAN configured, you can use this connection as an alternate path for normal traffic. Typically we don’t do this with 4G due to data connection charges, but with a guaranteed flat cost from a wireless ISP, this is a good option. 

The only downside to using a wireless ISP is that you are likely to have a different one in each geographic area which will require managing yet another carrier, whereas with 4G you can likely have one provider for all your sites. You have to decide which is more valuable—one carrier to manage, or a low-cost ISP that can be used for day-to-day traffic usage?

Conclusion

With so much of our data and applications residing in the cloud or at remote data centers, having viable alternatives for site redundancy is a necessary component to WAN design.  The likelihood of a primary circuit outage is real, and having an alternate path that is not hardwired provides extra protection.  Although covering every single failover possibility is usually too expensive, this one is worth considering.