I just noticed that mac address of a serial port is not there in a 2911 router in PT. also while using eui-64 the serial picks up the mac of some a gigabit or fast ethernet interface.

  • MAC addresses are used by IEEE LAN protocols (ethernet, Wi-Fi, token ring, FDDI, etc.), and some of those use 48-bit MAC addresses, and some use 64-bit MAC addresses. Other protocols use something different (DLCI, VPI/VCI, etc.) or nothing at all. – Ron Maupin Jan 5 at 18:39

Serial ports don't have or need MAC addresses. It's as simple as that.


MAC Addresses are specific to Ethernet interfaces - serial interfaces are point-to-point and use a different Layer 2 protocol (PPP, HDLC, FR etc.) for communication.

EUI-64 is most likely deriving it's address from another source on your router.

  • ... and to some other standards (some of which from the past) like Token Ring, FDDI, somewhat in Fibre Channel, ATM and others. – Marc 'netztier' Luethi Jan 6 at 14:27

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