what is static mac address of port CPU on switch?

vlan    mac address          type    ports
-----    -------------       -----   -----
ALL      0100.0ccc.cccc     static   CPU

On a switch 2960, I see twenty of them. What are they used for?

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Comments

crypticgeek

Speaking specifically to the MAC addresses not assigned to a physical port or logical one (like a VLAN), most likely they are used for addressing certain internal switch operations. Maybe someone with more knowledge of the IOS architecture can give a more specific answer, but I'm not sure how much those outside of Cisco really know in detail enough to answer with any certainly. If you notice at least some of the MAC addresses listed are multicast addresses, which depending on the framed protocol and specific switch may need to involve the CPU for some or all of their processing. Examples of this may be frames for CDP, VTP, STP, etc.