Wide Area Network (WAN) redundancy uses multiple connections to keep the network stable and avoid downtime. This strategy ensures uninterrupted connectivity, even when one link fails.
Data centers and colocations rely on WAN redundancy to improve disaster recovery and maintain reliable service.
This article explains WAN redundancy, its role in colocation, and how providers ensure stable connections through redundancy.
What Is WAN Redundancy?
WAN redundancy creates backup paths to keep the network always available. A WAN connects remote locations and serves as a gateway to external networks. It's typically at the edge of a local network.
By adding extra gateways, providers create backup paths. These paths ensure the network stays online even if an ISP, link, or local component fails.
A well-designed WAN redundancy strategy helps colocation providers keep services online. It also prevents data loss and boosts performance. Multiple connections and failover mechanisms reduce the chances of outages.
Why Is WAN Redundancy Important for Colocation?
WAN redundancy reduces disruptions by offering backup paths when network components fail. It ensures the network remains online despite hardware problems, ISP issues, or physical damage.
A redundant WAN setup offers:
- Stability. Traffic reroutes through a backup connection if the primary WAN link fails.
- Reliability. Extra paths protect against single points of failure, keeping access to essential services uninterrupted.
- Performance. Multiple WAN links help prevent congestion, improving overall network performance.
Since colocation data centers house critical IT infrastructure, uninterrupted network connectivity is essential. WAN redundancy allows colocation providers to guarantee clients stable, high-performance connections, even in failures and outages.
How Do Colocation Providers Achieve WAN Redundancy?
Colocation providers use various strategies to ensure WAN redundancy and prepare for network failures. These strategies help reduce the impact of issues like hardware malfunctions, ISP failures, or fiber cuts.
Below are some key redundancy strategies and examples.
Multiple Connections
To prevent internet disruptions, colocation providers connect to multiple ISPs. They use the Border Gateway Protocol (BGP) to route traffic dynamically. BGP selects the best path based on latency, bandwidth, and policy-based routing.
Colocation providers use different redundancy configurations for WAN connections:
- Single-homed. The provider connects to one ISP. This configuration offers no redundancy and is avoided in enterprise colocation environments.
- Dual-homed. The provider connects to one ISP with multiple links. The connections can be through one or multiple edge devices. The setup protects against a single link failure but relies on one provider.
- Single multi-homed. The provider connects to multiple ISPs using one link per ISP. The connections can include redundant edge devices. The setup protects against ISP failures but faces link failures.
- Dual multi-homed. The provider connects to multiple ISPs with multiple links to each ISP. It is the safest configuration, ensuring redundancy for link and ISP failures.
BGP detects network failures and reroutes traffic between ISPs. Colocation providers use Autonomous System (AS) numbers to manage routing policies across multiple ISPs.
A provider advertises its network prefixes to multiple ISPs and decides how traffic moves through the network. They carefully configure BGP routing policies to ensure failover occurs as expected since ISPs may prioritize their routes.
For example, if ISP 1 has an outage, BGP reroutes traffic through ISP 2 to ensure uninterrupted service. This dynamically changing routing policy enables failover and load balancing between different ISPs.
Diverse Fiber Paths
By installing multiple physical routes, providers prevent disruptions caused by fiber cuts or infrastructure damage. These redundant paths enter the data center from different locations to improve resilience.
For example, a colocation facility can have two fiber paths, one entering the facility from the east and another from the west. If construction work accidentally cuts one of the connections, traffic continues through the alternative path with no disruption.
SD-WAN
Software-defined WAN (SD-WAN) improves network efficiency by automatically selecting the best available connection. It optimizes performance by evaluating real-time conditions like packet loss, latency, and jitter.
SD-WAN uses overlay tunnels and applies dynamic path selection policies. It uses forward error correction (FEC) and packet duplication to improve resilience further.
SD-WAN detects latency issues and automatically reroutes traffic to a more stable link. The process is automated and does not require manual intervention.
Redundant Edge Devices
Colocation providers use multiple edge devices (routers and switches) to prevent single points of failure. Redundant routers use failover protocols (like VRRP and HSRP), ensuring traffic continues if one router fails. Switch redundancy relies on different built-in protocols (STP or MLAG) to keep the network stable.
If a primary router that handles WAN traffic fails, a secondary router, pre-configured with VRRP, automatically takes over. End-users experience continuous operation since failover occurs in milliseconds.
Cross-Connect
Providers offer private, high-speed connections between networks in the same data center to reduce reliance on external ISPs. Although it's not a WAN connection, it supports WAN redundancy by providing an alternative dedicated network inside a colocation facility.
Cross-connects use dedicated fiber or copper cables inside facilities to provide direct connectivity between tenants and cloud providers (such as AWS or Google Cloud). These connections minimize network hops, improve throughput, and reduce latency.
For example, a trading company that has colocation in a data center may utilize direct connections. Critical trading applications use cross-connect services instead of internet-based VPNs to ensure low latency and improved security.
Conclusion
This guide explained why WAN redundancy is essential for reliable colocation services, preventing downtime and ensuring continuous connectivity.
To further strengthen your network, read more about network infrastructure security.
