Designing a Resilient Direct Connect Architecture to Ensure Business Continuity

For enterprises that rely on Amazon Web Services Direct Connect (Direct Connect) for hybrid‑cloud connectivity, constructing a network architecture that can survive both planned and unplanned maintenance events is essential.

Defining Resilience

Resilience is not the same as redundancy. While having a primary and backup Direct Connect link provides redundancy, true resilience also requires proactive fault detection, rapid response, continuous operation during failures, and post‑event review.

Failure Scenarios

Scenario A: A global live‑streaming event that cannot tolerate any interruption.

Scenario B: A financial trading platform where even millisecond‑level latency spikes are unacceptable.

Both scenarios demand modeling of capacity and ensuring sufficient spare bandwidth to handle failover without congestion.

Direct Connect Maintenance Types

AWS classifies maintenance into Planned Maintenance and Emergency Maintenance. Planned maintenance follows a two‑stage traffic migration:

AS‑Path prepend : AWS adds three AS‑Path segments to make the route less preferred, giving your network time to react.

Route withdrawal : After a 60‑second window, AWS withdraws all routes learned from your on‑premises device, while the BGP session remains established for monitoring.

Before any change, AWS performs a comprehensive pre‑check to confirm the device is not carrying customer traffic.

Designing for Maximum Resilience

The recommended topology distributes connections across at least two Direct Connect locations, with two independent physical ports per location. This design eliminates single‑point‑of‑failure impact and maintains traffic flow even if an entire location fails.

In a primary/primary (active‑active) setup, ensure that each link’s utilization never exceeds the spare capacity of its counterpart, otherwise a single link failure will cause congestion.

Enabling BFD

Activating Bidirectional Forwarding Detection (BFD) on all Virtual Interfaces (VIFs) reduces BGP fault detection from the default 180 seconds to sub‑second intervals, dramatically shortening convergence time during emergencies.

Validating Resilience

Because Direct Connect is a shared, partially opaque service, regular manual traffic shifts to the redundant link, quarterly role swaps, and the Direct Connect Failover Test feature are recommended to verify that failover works as expected.

Summary

By implementing a maximum‑resilience topology (multiple locations, dual connections), enabling BFD for rapid fault detection, and routinely testing failover, organizations can keep critical workloads online during both scheduled maintenance windows and unexpected incidents, thereby meeting business‑continuity requirements.