Cisco Certified Support Technician (CCST) NetworkingIP ConnectivityMedium
A network architect is designing a routing solution for a campus network that requires fast convergence and support for unequal-cost load balancing. The network consists entirely of Cisco devices. Which routing protocol would be the most suitable choice to meet these requirements?
- ABGP
- BRIPv2
- COSPF
- DEIGRP
Show answer & explanationAnswer & explanation
Correct answer: D. EIGRP
EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary routing protocol known for its fast convergence (using DUAL algorithm) and its unique ability to perform unequal-cost load balancing. OSPF offers fast convergence but only supports equal-cost load balancing. RIPv2 is slow to converge and does not support unequal-cost load balancing. BGP is an exterior gateway protocol, not typically used for internal campus routing.
Why the other options are wrong
- A. BGP is an exterior gateway protocol used for routing between autonomous systems, not for internal campus network routing.
- B. RIPv2 is a distance-vector protocol with slow convergence and only supports equal-cost load balancing, making it unsuitable for the 'fast convergence' and 'unequal-cost load balancing' requirements.
- C. OSPF is a link-state protocol with fast convergence but only supports equal-cost load balancing, failing the 'unequal-cost' requirement.
EIGRP Features
EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary hybrid routing protocol known for its rapid convergence and support for unequal-cost load balancing.
- Uses DUAL (Diffusing Update Algorithm) for fast convergence.
- Supports unequal-cost load balancing.
- Cisco proprietary (though open standard in limited form now).
- Uses composite metric (bandwidth, delay, reliability, load).
Memory trick: Each protocol has its own 'personality' for speed and sharing.