Packet Timing and Failover Sensitivity in a Geographically Redundant MPLS Backbone: A Reproducible Scenario Assessment

Failover planning for geographically redundant Multiprotocol Label Switching (MPLS) backbones must distinguish directional rate adequacy, packet deadlines, and interruption loss. This study develops a reproducible assessment combining G.729 traffic accounting, stochastic route/recovery trials, and independently verified finite buffer packet events. At 462 calls and 11.85 Mbit/s per direction, three-realization delivery by 100 ms averages 99.721% for independent phases and 90.818% for a 4 ms phase cluster. A matched comparison across 64 policy cells admits 30 using mean delay and blackout criteria, 19 using the full packet criterion, and eight using a sufficient all-phase bound. These counts persist at timely delivery targets of 98%, 99%, and 99.5% with the original blackout limit. Normalized analysis and five traffic levels from −20% to +20% identify when additional capacity, deadline headroom, or shorter recovery is required. A targeted 800-trace extension uses fifty realizations per cell and bounded one-sided release delays of 1–2 ms. The tested admission contrast persists, while shorter typical deadline miss runs can coexist with slightly worse aggregate timely delivery. The contribution is a verified comparison of conditional planning decisions and continuity consequences. OPNET illustrations provide configuration provenance; operational transfer requires calibrated traffic, service, and recovery inputs.