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Network Convergence Time Calculator

Estimate convergence time for routing protocols with BFD comparison

Select the routing protocol. OSPF and EIGRP converge in seconds, while BGP can take minutes. BFD can dramatically reduce failure detection time for all protocols.
Interval between hello/keepalive packets. OSPF default: 10s (broadcast), 30s (NBMA). EIGRP: 5s. BGP: 60s.
seconds
Time to declare neighbor down after last hello. OSPF dead: 40s (4x hello). EIGRP hold: 15s (3x hello). BGP hold: 180s (3x keepalive).
seconds
seconds
Bidirectional Forwarding Detection interval. Typically 50-300ms. BFD detects failures in milliseconds instead of seconds, providing sub-second convergence.
ms

Convergence Comparison

Without BFD

Failure Detection
LSA/Update Propagation
SPF/Route Computation
RIB/FIB Update
Total Convergence

With BFD

Failure Detection (BFD)
LSA/Update Propagation
SPF/Route Computation
RIB/FIB Update
Total Convergence
BFD Improvement
References:
RFC 5880 - Bidirectional Forwarding Detection
RFC 2328 - OSPF, RFC 7868 - EIGRP, RFC 4271 - BGP
BFD provides sub-second failure detection independent of routing protocol