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3.1.3. First Hop Redundancy

FHRP (First Hop Redundancy Protocol): Provides gateway redundancy so clients don't need reconfiguration if their gateway fails.

Multiple routers share a Virtual IP (VIP). Clients point to the VIP as their gateway. If the active router fails, the standby takes over the VIP—seamlessly, without client reconfiguration.

Subinterfaces: One physical interface divided into multiple logical interfaces, each with its own IP and VLAN assignment. Used in "router-on-a-stick" configurations where a single router interface handles inter-VLAN routing through 802.1Q trunk subinterfaces.

Alvin Varughese
Written byAlvin Varughese
Founder•15 professional certifications