Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureEasy
A network engineer is configuring a Layer 3 switch to act as a default gateway for multiple VLANs in a campus network. To provide high availability, the engineer wants to ensure that if the primary switch fails, another redundant Layer 3 switch can automatically take over the default gateway role with minimal disruption. Which protocol should be configured?
- ABorder Gateway Protocol (BGP)
- BLink Aggregation Control Protocol (LACP)
- CSpanning Tree Protocol (STP)
- DVirtual Router Redundancy Protocol (VRRP)
Show answer & explanationAnswer & explanation
Correct answer: D. Virtual Router Redundancy Protocol (VRRP)
Virtual Router Redundancy Protocol (VRRP) is a First Hop Redundancy Protocol (FHRP) that provides automatic default gateway failover. It allows multiple routers/switches to share a single virtual IP address and MAC address, ensuring continuous connectivity even if the primary device fails.
Why the other options are wrong
- A. BGP is an exterior gateway routing protocol used for routing between autonomous systems on the Internet, not for local default gateway redundancy.
- B. LACP bundles multiple physical links into a single logical channel for increased bandwidth and link redundancy, but not default gateway redundancy.
- C. STP prevents Layer 2 loops and does not provide Layer 3 default gateway redundancy.
Virtual Router Redundancy Protocol (VRRP)
A First Hop Redundancy Protocol (FHRP) that provides automatic failover for the default gateway, ensuring high availability for end devices.
- Creates a virtual router with a virtual IP and MAC address.
- One router acts as master, others as backups.
- Standardized protocol, alternative to HSRP.
Memory trick: FHRP is like having a backup key for your front door.