Why doesn't the big package get through?

Question

linux

There is such question:
In the test environment there are three computers - comp1 com2 and comp3
On comp2 and comp3 in settings of the network card included jumbo frame. Now they ping each other with large packets - ping comp2 -l 8000 -f
Also these two computers ping with comp1 regular packets. But if you try to ping them big, but without a flag prohibiting fragmentation, there is no connection.
The question is why? As far as I understand, if the network card has a standard mtu, then it should fragment large outgoing packets of 1500 bytes. Where am I wrong?
Although, if the receiving side fragments, then everything is correct. After all, the answer also comes in the same size, and is discarded by the network card?

Answer 1

Look with wireshark to see what comes back to you. Most likely, echo reply 8000 MTU is not accepted by the network card, on which jumbo is disabled.
In general, according to the description, it is very similar to a black hole, but nothing is blocked for you, right?

Answer 2

If you enable jumbo frame, then it must be enabled on all devices in the segment.
Otherwise, devices on which it is not enabled will not be able to work, those who have a jumbo frame.
In other words, there is no fragmentation in ethernet frames, and when a large frame arrives at a device that is not waiting for it, then this frame will simply be rejected. Moreover, one JF will be perceived by the host as two frames, which will further aggravate the situation.
https://ru.wikipedia.org/wiki/Jumbo frame

Answer 3

Install new switch or medic