Equal-Cost Multi-Path (ECMP) uses multiple paths simultaneously. Every leaf has equal-cost paths through each spine.
How ECMP works:
Routing protocol advertises equal-cost routes
Switch hashes packet headers
Hash selects which path to use
Flows between same endpoints take same path
Benefits:
- All links carry traffic
- Adding paths increases bandwidth
- No spanning tree blocking
With spines, each leaf-to-leaf path has options. ECMP spreads traffic across all .