Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureEasy
A network engineer is configuring a new Layer 3 switch to act as a default gateway for multiple VLANs. To provide redundancy and high availability for the default gateway, two Layer 3 switches will be used. The requirement is that one switch actively forwards traffic, while the other remains in a standby state, taking over seamlessly if the active switch fails. Which protocol should the engineer configure to achieve this?
- AOSPF (Open Shortest Path First)
- BVRRP (Virtual Router Redundancy Protocol)
- CGLBP (Gateway Load Balancing Protocol)
- DHSRP (Hot Standby Router Protocol)
Show answer & explanationAnswer & explanation
Correct answer: D. HSRP (Hot Standby Router Protocol)
HSRP (Hot Standby Router Protocol) is a Cisco proprietary First Hop Redundancy Protocol (FHRP) that allows two or more routers to share a single virtual IP address and MAC address, with one router acting as active and the other as standby. This provides seamless failover for the default gateway.
Why the other options are wrong
- A. OSPF is an interior gateway routing protocol, not an FHRP.
- B. VRRP is an open-standard FHRP, similar to HSRP, but HSRP is Cisco proprietary and common on Cisco devices.
- C. GLBP provides load balancing across multiple gateways, not just active/standby.
Hot Standby Router Protocol (HSRP)
A Cisco proprietary First Hop Redundancy Protocol (FHRP) that provides high network availability by providing a default gateway IP address that is always available.
- One router is Active, forwarding traffic.
- Another router is Standby, monitoring the Active router.
- Uses a virtual IP and MAC address for the default gateway.
Memory trick: FHRP: Your Gateway's Backup Plan.