Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureEasy
A network engineer is configuring a new Layer 3 switch to act as the default gateway for multiple VLANs in a data center. The design requires high availability for the gateway, ensuring that if the primary switch fails, another switch can immediately take over the role without any disruption to client connectivity. Which First Hop Redundancy Protocol (FHRP) is commonly used and provides active-standby redundancy with a virtual IP address and MAC address?
- AGLBP
- BHSRP
- CPIM-SM
- DVRRP
Show answer & explanationAnswer & explanation
Correct answer: B. HSRP
HSRP (Hot Standby Router Protocol) is a Cisco-proprietary FHRP that provides active-standby redundancy. It allows two or more routers (or Layer 3 switches) to share a virtual IP address and MAC address, ensuring that if the active device fails, the standby device seamlessly takes over the default gateway role.
Why the other options are wrong
- A. GLBP (Gateway Load Balancing Protocol) provides load balancing across multiple active gateways, which is not the primary requirement of 'active-standby redundancy'.
- C. PIM-SM (Protocol Independent Multicast - Sparse Mode) is a multicast routing protocol and not an FHRP.
- D. VRRP (Virtual Router Redundancy Protocol) is an open-standard protocol providing similar active-standby functionality to HSRP, but HSRP is Cisco-proprietary and very common in Cisco environments.
HSRP (Hot Standby Router Protocol)
A Cisco-proprietary First Hop Redundancy Protocol (FHRP) that provides high network availability by providing a virtual default gateway for IP hosts on a LAN.
- Cisco proprietary.
- Active-standby redundancy model.
- Uses a virtual IP address and virtual MAC address.
- One router is Active, one is Standby, others are Listeners.
Memory trick: FHRPs: Your gateway always stays up.