I connected two pcs to a switch in packet tracer , no ip addresses at all.and on switch cli I put a show mac address-table command,why there is nothing shown in the table?how does the switch so learn mac addresses?any one helps,please.I am a beginner in netwroking ,thanks

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    Dec 15, 2019 at 5:41

2 Answers 2


When PC send a frame switch learning his MAC address via looking in frame header and checking source MAC address.

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    – kubn2
    Jul 19, 2019 at 7:46

A switch learns MAC-port associations by inspecting the source address of frames received on a port (self-learning MAC bridge).

If a node doesn't send any frame (which may be the case if IP is deactivated and nothing else is active) the switch can't learn its MAC address.

  • But when I connect another switch to the first switch , its MAC address is shown in the table.why? Jul 19, 2019 at 8:01
  • "Its" = the non-IP node one? No. If the first switch doesn't see a frame from that node, the second one can't see one either. Possibly that is a glitch in Packet Tracer, in reality it's impossible.
    – Zac67
    Jul 19, 2019 at 8:21

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