Failover Strategies Against Network Failures

Business processes depend more and more on functioning networks. The network edge is where the device or local area network communicates with the Internet. To ensure reliability, many companies rely on SD-WAN, software-defined network structures.

Modern 4G-LTE and 5G technologies can supplement conventional cable connections in the SD-WAN orchestra – and are often the first choice, for example, when non-stop availability of Internet connections is essential. In the case of company branches or branches, there are a few unique features to consider.

A small group of risk points is responsible for most network problems. The following six failover strategies can counteract this.

Connectivity Diversity At The Edge

WAN connections to branch offices are usually based on just one or two lines from an Internet Service Provider (ISP) shared by several consumers. This connection to the corporate network and cloud is vulnerable because it can be disrupted in various ways, such as weather events or construction work.

Connections such as 4G LTE and 5G gigabit-class are more flexible and faster than wired lines. With the help of such wireless connections, special wireless routers create a failover in the event of a network failure. Network managers can also use these connections to monitor and troubleshoot the router and other devices in the branch office.

Dual Carrier Connectivity

Dependence on just one cellular network operator or Internet provider can be risky for uninterrupted operation: Network congestion, routing, DNS problems, and network core failures can cause disruptions. In wireless WAN architectures, at least two connections from different operators should therefore be used because it is unlikely that both networks will fail simultaneously.

LTE or 5G routers with at least two modems or a SIM card extension can be set up for this carrier redundancy. Both connections can be bundled for additional capacity at peak times.

Hardware Redundancy

Redundant or mirrored routers often also protect against failures. They monitor each other and create automatic failover if the primary router or WAN link fails. Updates, configuration changes, and other maintenance work can be carried out without jeopardizing communication.
Modern end devices use the Virtual Router Redundancy Protocol (VRRP) to configure and coordinate the failover. The routers are connected directly via a cable or an Ethernet switch, share a virtual gateway address and a DHCP table, and thus act as a router for other devices in the network. During the failover state, the former primary router continually monitors its WAN connection and signals the backup router when it can switch back over.

Secure Connection Via VPN Tunnel

Multiple direct Internet connections via VPN tunnels to various input devices can ensure uninterrupted communication between the branch and head offices. A configuration of so-called dynamic multipoint virtual private network tunnels (DMVPN) is possible from each branch to redundant devices.

Each tunnel is routed independently over the Internet, and the data traffic is dynamically routed via the most effective connection. If network or hardware problems disrupt a tunnel, traffic is sent over the alternate path.

Cushion Traffic Peaks

Increasing video usage, file sharing apps, software updates, and the increasing number of connected devices often contribute to spikes. A backup connection based on mobile communications can offer relief here. Routers with SD-WAN functionality dynamically load balance traffic to the best available path. When the peak traffic subsides, the wireless connection is automatically and invisibly disconnected in the background, allowing employees to continue working without interruption.

Remote Management In Routine And Emergency

Cellular wireless connections can also provide an alternate network connection when the end device is unreachable over primary links. Routers configured for use at the edge of the network have so-called out-of-band management functions. The responsible persons access the device remotely via a wireless connection to solve problems without an on-site visit.