Eigrp Psychological Warfare

The Psychological Warfare of Cisco’s EIGRP Metrics

EIGRP metrics are what happens when network engineers have too much coffee and decide that five variables aren’t nearly complicated enough. While OSPF just uses cost and BGP uses a handful of attributes, EIGRP went full mad scientist with bandwidth, delay, load, reliability, and MTU. It’s like they were trying to create the networking equivalent of a German compound word.

The formula itself looks like something you’d find carved into the wall of an abandoned mathematics department: metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)]. I spent three months at Florida Blue trying to explain to management why our network was choosing seemingly insane paths, and it always came back to someone, somewhere, tweaking a K-value without understanding the butterfly effect they were unleashing.

The real joke is that despite having all these knobs to turn, everyone just uses the default K-values anyway, which essentially reduces EIGRP to “bandwidth plus delay.” It’s like buying a Swiss Army knife and only using the bottle opener. But Cisco keeps all those other metrics in there, waiting, like dormant DNA from our networking evolutionary past, ready to confuse junior engineers who accidentally enable K2 and wonder why their network just had a nervous breakdown.