Overview
Enhanced Interior Gateway Routing Protocol (EIGRP) is often called a 'hybrid' protocol. It uses the Diffusing Update Algorithm (DUAL) to ensure fast convergence and loop-free paths.
Key Features
- Metric: A composite metric based on Bandwidth, Delay, Reliability, and Load (though usually only Bandwidth and Delay are used).
- Partial Updates: Only sends changes when they occur, rather than the full table.
- Neighbor Discovery: Uses Hello packets to maintain relationships.
- Unequal Cost Load Balancing: Can distribute traffic across multiple paths with different metrics.
History
Originally a Cisco proprietary protocol, it was partially opened as an IETF draft in 2013.