Service chaining routes traffic through a sequence of network functions. Each function processes traffic before passing it to the next.
Example chain: Firewall, then IDS, then Load Balancer, then Web Server.
Without service chaining: Manual VLAN configuration, static routing, changing the chain means reconfiguring everything.
With service chaining: Define chain in software. Traffic steered automatically. Add or remove functions dynamically. Scale independently.
Implementation methods: NSH headers identify chain and position. Policy-based routing. VXLAN stitching via controller.