After the SFD come two MAC addresses, bytes each. The destination MAC appears first. Switches read this to decide where to send the frame. The source MAC follows. Switches use this to learn which port leads to that device. If the destination is FF:FF:FF:FF:FF:FF, the frame goes to all ports. I'll explain how switches build their MAC tables soon.
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$ curl repovive.com/roadmaps/network-design/physical-and-data-link-fundamentals/destination-and-source-mac
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