01-00-0c-cc-cc-cc

Unanswered Question
Jul 29th, 2008
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Hi,


A quick question. Do you see 01-00-0c-cc-cc-cc system MAC address as being broadcast or multicast?


I can find arguements to both, but I am interested to hear more opinions.


Thanks,

David

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a.alekseev Wed, 07/30/2008 - 00:16
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01-00-0C-CC-CC-CC 0x0802 CDP (Cisco Discovery Protocol), VTP (Virtual Trunking Protocol)

andrew.burns Wed, 07/30/2008 - 03:56
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Hi,


You can directly look this up in the IEEE 802.3 standard documents. (Section 1, sub-section 3.2.3.1), to quote:


All 1's in the Destination Address field shall be predefined to be the Broadcast Address.


So, to answer the question, you can say that 01-00-0c-cc-cc-cc is definitely not a broadcast address (because it's not all 1's). However, as the I/G bit is 1 it is a group (or multicast) address. (The broadcast is a sub-type of multicast - but the reverse isn't true)


HTH

Andrew.


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