Top 4 questions you need to ask before you buy a Multi-Network Gateway
A key requirement when selecting an LTE gateway that supports multiple Wide Area Network (WAN) links is the performance and the policies that define the switching behavior between WAN links. If you’re spending the extra money to buy a multi-network mobile gateway, you want to make sure that you’re actually going to get the performance you presumably want for your money, writes Bryan O’Flaherty Wills, the director of product management at Sierra Wireless.
All of the applications running in your vehicle are mission critical, and all require secure wireless connectivity to the core enterprise or corporate networks. You expect to get the best connectivity possible, when you need it, wherever you are to support such as CAD/AVL, dispatch, video and others. You don’t want connectivity to get in the way of carrying out their jobs, nor do you want to think about the connectivity.
Customers look to using a multi-network gateway for several key reasons including performance and connectivity. In terms of performance, Wi-Fi provides fastest data throughput for the least cost, which makes it ideal in the depot, garage or hospital. This performance is needed for applications like uploading video or downloading large map files that are required.
Customers also require connectivity, anywhere, and anytime. When Wi-Fi coverage is not available for best performance, cellular provides the connectivity needed everywhere else. And if a specific cellular carrier cannot provide the coverage required or goes down, then a second cellular carrier (or public safety network such as Band 14) can be used as backup.
Customers are faced with many choices for gateways claiming to support Multi-WAN. But how do you decide which is best for you? You should consider how a gateway will perform in the following situations:
Switching from Depot Wi-Fi to Cellular such as a Fire truck leaving the station and switching from Wi-Fi to cellular coverage.
Switching from a Cellular Network to Depot Wi-Fi such as an Ambulance returning to a station and needing to connect to Wi-Fi from cellular
Switching between Cellular Networks such as a police car losing coverage on one cellular network must switch to a secondary cellular network.
There are several vendors claiming to be able to provide this multi-WAN switching capability but you need to understand the differences in how this switching is done because it has real implications for how your mobile workforce is connected in the field. Look for the following:
- Does the gateway keep all the WAN radios active at all times?
Are all the WAN radio links active during operation, and is the gateway aware of its environment so that it can at least sense and assess the state of a link, where you’re located, and switch the traffic and all your data? In most you will find that the answer is no. And if the answer is no, it’s like starting from scratch every time you need to make a switch. The radio module has to boot up from idle and connect, which takes time. And in that time, your users are not connected to a network. So while a vendor may claim multiple WANs and failover, it’s not multi-WAN seamless switching. If this connectivity is mission critical, find a vendor that has all WANs in hot standby.
- Does the gateway switch from WAN to WAN based only on network priority?
If so, what will happen is, as your vehicles leave the station or depot, the gateway may still see and stay connected to the Wi-Fi access point or base station and the performance throughput on the link will degrade to the point that it is unusable before the connection is dropped completely, and only then will the gateway switch to a different WAN. During this delay, your workforce will experience poor or no connectivity for a longer period until the switch happens. To avoid this, look for a vendor that performs the switching based on policies other than network priority alone. Look for switching policies based on a number of variables including network priority, signal strength, vehicle speed, time and location.
- How does the gateway decide which network should be used, and when connectivity is lost, how does it determine when to return to the primary network?
If the gateway has to start from zero every time a switch is made, how does it return to your primary network (assuming it allows you to define a primary network). If it tries to return to the primary constantly, it may return under suboptimal conditions and drop connectivity again – so hopping back and forth. Look for policies that take a long look at the original network connectivity before deciding to return. You want to make sure that your gateway doesn’t end up in a cycle of network switching needlessly as this also results in your users being disconnected.
- What happens to my VPN tunnel when I switch between WAN links?
With an idle radio that needs to boot, and a connection that has disconnected, the VPN tunnel already established needs to be torn down and rebuilt on the new link. This can take several seconds, and can be disruptive to user applications such as streaming video or CAD applications that can’t tolerate a break in connection. Look for a solution that offers a mobile-optimized IPsec VPN that seamlessly switches the VPN tunnel and maintains session continuity for applications when roaming across networks instead of tearing down the VPN, and re-building a new tunnel.