EIGRP metric calculation (classic and wide)

[iores]

Hi

I have two routers: A---B.

Router B is redistributing static route with redistribute static command. This means that it uses the bandwidth and delay of the interface from which it is sending advertisement as seed metric. 

This seed metric is in classic mode, and eqauls 2816 (BW 1.000.000 Kbit, Delay 10 microseconds).

On router A, the path metric to redistributed static route is in wide mode 66.846.720/1.310.720 (min. BW 10.000 Kbit, Delay 20.000.000 pico seconds).

RIB scaled metric is 66.846.720/128 = 522.240

How did it get 66.846.720/1.310.720? 

I cannot get the exact same numbers. I get 65.667.072 using wide metrics formula for Router A.

[Giuseppe Larosa]

Hello @iores ,

EIGRP classic metric provides a 32 bit unsigned integer that fits the size of the metric in the IP routing table.

EIGRP wide metric is 64 bit wide unsigned integer and the scaling factor is used to scale down to a value that can fit in a 32 bit integer to be put in IP routing table by IP routing table daemon.

So you cannot mix the two types of metrics or you use classic metric (32 bit ) on both or you use wide metric ( 64 bit scaled down to 32 bit) otherwise you get non consistent results like in your lab

Edit:

EIGRP metric calculations are made on integers not on floating (real numbers) so likely there are errors introduced by this. When we use a calculator and we apply the formulas we use floating numbers by default. This is likely the reason why you get different results.

Hope to help

Giuseppe

[paul driver]

Hello
Please review this- Wide metric calculation