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A switch doesn't alter the frame, and source/destination mac addresses remain how sending host specified them,so let me say it again Layer 2 Switching never changes the frames means no changes in MAC and in CRC values,switches either flood, forward, or filter MAC addresses. Since they do transparent bridging by nature!

Every single port on a switch has its own mac address then what are they used for?

there are some posts and discussion over this subject but there is no clear satisfying valid answer.

in this link here the guy says Switch changes the source mac address to its own port MAC addresses when want to flood or do any kinda transmission but provides no reference to that which kinda seems to be wrong!

Teun Vink
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user7741
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    identity of the port, layer-3 use of the port, ... a manufacturer could use them any way they want. Does a layer-2 port need a MAC? Of course not as nothing talks to the port itself. – Ricky Sep 09 '14 at 19:50
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  • identity of the port for what reason,sw gonna work transparent, 2.Layer3 usage is acceptable answer,3."manufacturer could use them any way they want" what are the examples??
    • – user7741 Sep 09 '14 at 20:40
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    Very good question. Simple switches don't need a MAC address for each interface. – Navin Mar 19 '16 at 08:39
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer. – Ron Maupin Jan 03 '21 at 21:32