Consider the two devices:
A: PC, NIC MTU is set to 1500
B: Router, MTU of relevant interface is 1478
Now if A
sends a frame of length 1500
to B
, something might go wrong. But what if I set A
's MTU to 1400? Now A
to B
should be OK, what will happen when B
sends a frame of length 1478
to A
? MTU
setting of 1400
indicates A
should drop a frame longer than 1400
, But since 1400
is a manually set value, A
's NIC is capable of processing frames of length 1478
.
This post suggests
MTU is the Maximum Transmission Unit, the largest packet of data that a computer interface will send.
MTU
only affects sending. Therefore, A
will accept frame of length 1478
even if its MTU is set to 1400
.
Wikipedia suggests
the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction
that can be communicated means '''A''' should reject frame of 1478
since it is not valid at all.
Here is my question: Does MTU setting affect sending, receiving, or both?