Terminology » Networking Basics » IGRP vs EIGRP: Key Differences in Routing Protocols

IGRP vs EIGRP: Key Differences in Routing Protocols

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This article highlights the key differences between IGRP (Interior Gateway Routing Protocol) and EIGRP (Enhanced Interior Gateway Routing Protocol), two important routing protocols.

IGRP vs EIGRP

FeatureIGRPEIGRP
Full FormInterior Gateway Routing ProtocolEnhanced Interior Gateway Routing Protocol
Protocol TypeDistance Vector ProtocolAdvanced Distance Vector (Hybrid)
Derivation-Derived from Interior Gateway Routing Protocol (IGRP)
MetricsBandwidth, Load, Delay, MTU, and ReliabilityBandwidth, Delay, Load, and Reliability
Path CalculationDistance vector algorithm with variance for load balancingDiffusing Update Algorithm (DUAL)
Area/Table SupportNo area support, supports multi-part routingSupports neighbor tables, topology tables, and routing tables
Maximum Hop Count255 (Default: 100)255

Key Differences Explained

  • Full Form: IGRP stands for Interior Gateway Routing Protocol, while EIGRP stands for Enhanced Interior Gateway Routing Protocol. The “Enhanced” in EIGRP signifies improvements over its predecessor.

  • Protocol Type: IGRP is a traditional distance vector routing protocol. EIGRP, while based on distance vector principles, is considered an advanced distance vector or hybrid protocol because it incorporates features from link-state protocols.

  • Metrics: Both protocols use metrics to determine the best path, but IGRP considers MTU (Maximum Transmission Unit) in addition to bandwidth, load, delay, and reliability. EIGRP excludes MTU from its metric calculation.

  • Path Calculation: IGRP relies on the classic distance vector algorithm. EIGRP uses the Diffusing Update Algorithm (DUAL), which allows for faster convergence and loop prevention.

  • Area Support and Tables: IGRP does not support areas or tables, using multi-part routing instead. EIGRP utilizes neighbor tables, topology tables, and routing tables for a more structured approach to routing.

  • Hop Count: Both protocols have a maximum hop count of 255, providing a limit to the number of routers a packet can traverse. The default hop count for IGRP is 100.