Strangler-Fig pattern applied to payments migration across three network stages, progressively shifting traffic from monolith to dedicated payments service. Stage 1 routes all checkout traffic through the monolith; Stage 2 introduces a routing proxy with feature flags to read from the new payments service while dual-writing; Stage 3 darkens the monolith path as the payments service owns all writes. Each stage maintains network isolation via VLANs (10, 20, 30) and preserves production stability through gradual cutover. Fork this diagram to customize your own strangler migration timeline, feature flag logic, or database failover strategy.