Implementing and Operating Cisco Enterprise Network Core Technologies (ENCOR) v1.2InfrastructureEasy
A data center network uses multiple Layer 3 switches for routing between VLANs. Engineers observe that traffic for a specific destination is always forwarded through the same path, even when multiple equal-cost paths exist. They want to utilize all available bandwidth by distributing traffic across these equal-cost paths. Which Layer 3 feature should be enabled or verified to achieve this goal?
- AVRRP
- BPort-channel
- CECMP
- DHSRP
Show answer & explanationAnswer & explanation
Correct answer: C. ECMP
Equal-Cost Multi-Path (ECMP) routing allows a router or Layer 3 switch to use multiple best paths to the same destination. Instead of choosing only one path, ECMP distributes traffic across all equal-cost paths, increasing bandwidth utilization and providing redundancy.
Why the other options are wrong
- A. VRRP (Virtual Router Redundancy Protocol) is another first-hop redundancy protocol, similar to HSRP, and does not distribute traffic over equal-cost paths.
- B. Port-channel (EtherChannel) aggregates multiple physical links into a single logical link at Layer 2 or Layer 3, not for distributing traffic over distinct Layer 3 paths.
- D. HSRP (Hot Standby Router Protocol) provides first-hop redundancy for default gateways, not traffic distribution over equal-cost paths.
Equal-Cost Multi-Path (ECMP)
A routing strategy where multiple best paths to a destination, having the same cost, are utilized simultaneously to distribute traffic, improve bandwidth utilization, and provide redundancy.
- Distributes traffic across multiple equal-cost routes.
- Increases effective bandwidth and provides load balancing.
- Supported by most modern routing protocols (OSPF, EIGRP, BGP).
Memory trick: ECMP: Every Connection Maximizes Paths