I'm confused about something I'm new to this, for example I use network switches in my network they support RSTP protocole, So let say every switch have 5 port. Switch base MAC address , aa:bb:xx:yy:zz:00 so port 1 bpdu send aa:bb:xx:yy:zz:01, port 2 aa:bb:xx:yy:zz:02 and port 3 ..etc. When I add new network switch to this network,Should the new device's MAC address be equal to the other device's (base MAC address + port number)? A mean new switch MAC addres start with aa:bb:xx:yy:zz:06 ? How are these MAC address conditions taken into account when producing RSTP devices? How can I find a resource on this?

  • Did any answer help you? if so, you should accept the answer so that the question does not keep popping up forever, looking for an answer. Alternatively, you could post and accept your own answer.
    – Ron Maupin
    Commented Dec 23, 2021 at 16:36

1 Answer 1


Should the new device's MAC address be equal to the other device's (base MAC address + port number)?

No, definitely not. The vendor is required to provide unique addresses and ranges to each device. I'm referring to a device's source MAC address, of course.

"Unique" in this case might not be literally globally and eternally unique, but unique enough so that no two devices with the same MAC could ever meet each other.

  • Thank you for your explanation. A mean manufacturer produce network device which have aa:bb:cc:dd:ee:00 and its device have 6 port So, Is manufacturer produces new device MAC address start with aa:bb:cc:dd:ee:06 ? Commented Feb 9, 2021 at 12:48
  • Usually, LAG trunks and virtual interfaces (SVI, loopback, ...) each have their own address, so a 6-port switch might need an allocation of at least 16 addresses.
    – Zac67
    Commented Feb 9, 2021 at 12:53
  • this is good question for me thank you NetworkStudent and good answer for me @Zac67 . A mean aa:bb:xx:yy:zz:00 mac address device could have 16 address inside maybe more. If the manufacturer produces aa:bb:xx:yy:zz:00 switch than other device MAC address start with least aa:bb:xx:yy:zz:00 + 16 address ?
    – hobik
    Commented Feb 9, 2021 at 13:00
  • 16 addresses would mean :00 through :0f in the last octet (or :10..1f, :a0..af and so on). The vendor needs to make sure that the device won't ever use more addresses than it's been allocated.
    – Zac67
    Commented Feb 9, 2021 at 13:07
  • Don't forget to accept an answer when your question is answered. ;-)
    – Zac67
    Commented Feb 9, 2021 at 21:21

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