MTU in EIGRP Metric

In Eigrp, Metric is calculated by using below formula.

metric = {K1*BW + [(K2*BW)/(256-load)]+(K3*delay)}*{K5/(reliability+K4)}

As we can see MTU is not present in it. So how it is impacting the EIGRP calculation?

The answer is it will not take part in route election till the time maxixmum path is not crossed. Changing MTu will not initiate the routing recalculation.

MTU is only in use when router has many routes for the destination and due to the maximum path restriction ( default or configured) it has to reject few routes then it will reject the routes with lowest MTU .

Let’s suppose if router has 16 routes for same destination and we have configured the maximum path to 4. 

So the question is how the router will select the 4 routes out of 16 best available routes. Router rejects the routes which  have the lowest MTU values. MTU is checked only on the incoming interfaces rather than outgoing interfaces.