A Guide to Network Redundancy in Data Centers

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A Guide to Network Redundancy in Data Centers
Data center network redundancy ensures reliable connectivity by minimizing downtime risks with backup connections and equipment.
If your data center is up but its network connection is down, you have a big problem. The reliability of a data center’s physical systems, like power and cooling infrastructure, matters little if the network that connects it to the outside world stops working.
This underscores the importance of network redundancy for data centers. Redundant network connections and equipment help to minimize the risk of network downtime, one of the greatest threats to data center reliability.
But what exactly does it mean for a data center to provide redundant networking? And how can businesses assess the network redundancy levels offered by a facility? Read on for guidance as we unpack what data center network redundancy means in practice.
What Is Data Center Network Redundancy?
Data center network redundancy means the availability of more than one network connection that allows workloads inside a data center to interface with those hosted elsewhere.
Redundant networks typically provide multiple means of connecting to the internet. But they can also take the form of redundant data center interconnections, meaning dedicated connections to other data centers that typically allow information to move faster and more reliably than it can over the generic internet.
Network redundancy minimizes downtime risks by using backup ISPs, cables, and failover systems. (Getty Images)
The Importance of Network Redundancy
The reason why network redundancy benefits data centers is simple enough: Individual network connections can fail. Having alternative connections available offers a backup solution in case the primary network that a workload or business relies on becomes unavailable.
Components of Network Redundancy in Data Centers
The concept of network redundancy inside data centers is simple enough in the abstract. But to put it to work into practice, data center operators must deploy several specific types of resources in duplicate form:
ISPs: Allowing multiple internet service providers (ISP) to serve a data center ensures that network connectivity will remain available if one ISP’s infrastructure goes down.
Physical cables: Each ISP should connect to the data center using a unique cable – and ideally, the cables will enter the facility at different locations. This setup reduces the risk that a localized problem (like a contractor accidentally digging up a cable, or a physical attacker cutting one) will cut connectivity to the entire data center.
Network switches and routers: Switches and routers must be deployed to eliminate single points of failure, ensuring connectivity remains intact even if one fails.
Automated routing and failover: To leverage network redundancy fully, data centers should have network routing and failover capabilities in place that can automatically redirect traffic in the event that one network fails.
The Limits of Redundant Networking
Importantly, even with resources like those described above in place, there are no guarantees that redundant network connections will prevent network-related outages.
A key challenge is that workloads typically use only one network connection at a time, as servers route traffic through a single external IP address. If that one connection fails, it can take anywhere from a few seconds to several minutes to switch over to a backup network.
There’s a way around this: Bonded networking, which makes it possible for servers to route traffic across multiple connections simultaneously. If one connection fails under a bonded setup, packets instantly and automatically use other connections to reach their destination.
The caveat is that bonded networking requires routers that can support this capability. It’s easy enough to implement bonded routers for all data flowing in and out of a data center. But it becomes trickier to take full advantage of network bonding in settings like colocation facilities, where multiple organizations deploy workloads with varying networking priorities and configurations – which means they can’t always share a single bonded router. Colocation providers sometimes offer access to network redundancy services that leverage bonding to increase reliability, but they are usually an extra service that increases costs.
The point here is that just because redundant networking is available in a data center doesn’t necessarily mean that a particular server or workload can fully benefit from it. It depends on the data center’s overall network architecture, and which types of networking capabilities are available on a workload-by-workload basis.
What to Consider When Assessing Network Redundancy in Data Centers
For organizations seeking a reliable data center for hosting workloads, it’s critical to evaluate more than just the high-level promises data centers providers make about network redundancy.
Virtually all data centers have redundant networks, meaning they connect to multiple ISPs and use multiple switches and routers. But some data centers offer more redundancy than others – plus, the ability of individual workloads to take full advantage of redundancy capabilities varies based on network and server infrastructure setups.

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