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STP and selecting priority

datchchadatchcha Member Posts: 265
in CCNA & CCENT
I already understand if default priority is used, then the MAC address is used to determine root bridge and which port is put in blocking state.

Question: Is the OUI portion of the MAC address used in this calculation? Example: 00.00.8c.00.98.70. The OUI is 00.00.8c. So should i know pay attention to 00.98.70 when trying to determine this? Should i convert the address to decimal or binary to assist in troubleshooting?

thanks.
Arrakis
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    jediknightjediknight Member Posts: 113
    Yes, the OUI is used in this calculation. For example if the OUI of one switch (lets call it A) was 11:11:11 and the OUI of another (lets call it B) was AA:AA:AA as well as the default priority was 32768 on both switches then A would be declared root switch in this STP topology.

    You should know that the MAC address is used if the default priorities are the same, but I would make sure to give more attention to the switch priority since you would more likely see value changed in both the exam and real world when configuring STP parameters.
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