How does a router calculate a MTU

Question

For a given link type, how would a router calculate it's MTU?

I initially thought of it taking a brute force approach, using a binary search to figure out the point at which the link fails to support a packet.

But, wouldn't this require a protocol to get a response (ACK) (so the router knows the packet was actually successfully sent)

Does it use a timeout system?

score 2 · Answer 1 · answered May 28 '19 at 21:43

2

Routers do not calculate the MTU. The MTU is a function of the layer-1/2 interface. For example, the MTU of ethernet is 1500 bytes. Other protocols will have other MTU sizes. That is something inherent in the interface and protocol, so a router or other device knows what the MTU of the link is.

answered May 28 '19 at 21:43

Ron Maupin

98,218
26
115
191

There are 2 Ron's. It's confusing – Tobiq May 28 '19 at 23:27
There used to be more. :) – Ron Maupin May 28 '19 at 23:28
I’m the good looking one :) – Ron Trunk May 29 '19 at 01:35

How does a router calculate a MTU

1 Answers1