Routing resilience is a network’s ability to keep traffic moving when one path disappears. It depends on having alternate routes, routers that can recalculate paths quickly, and enough capacity on backup links to absorb the load. In practical terms, a resilient network should fail over without major interruption when a leased circuit ends, a fiber is cut, or a provider withdraws a route.
This matters in cyber security because availability is part of security. Attackers may try to disrupt routing by damaging infrastructure, exhausting links with DDoS traffic, or manipulating internet routes with BGP hijacks. Defenders build routing resilience with redundancy, diverse physical paths, route monitoring, and regular failover testing. In critical networks, the goal is not just to survive a single outage, but to avoid surprise when a dependency changes and to keep essential services reachable.