STP ethertype


I don't see what is the ethertype for STP. Is it similar to the protocol identifier, which is 00-00 ?

Thanks for your opinion, best regards, Michelot

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the standard you want is 802.1D - note there are lots of follow ons.

however - it doesnt use an Ethertype, but uses the "SAP and length" type ethernet format.

the IEEE put the standards online

formatting link
try a search on something like 802.1d spanning tree

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Bonsoir Stephen,

Thanks for your words.

Yes, I found this. It seems it's a rare case where we have still the length instead of the EtherType.

And there is either the SNAP encapsulation, either the LLC no SNAP encapsulation.

Case 1 that I translated from a trace found on the web:

DA = 01-00-0C-CC-CC-CD, SA = 00-02-7D-71-B8-C1, Length = 00-40, LLC SNAP = AA-AA, CTRL = 03, OUI Cisco = 00-00-0C, PID PVST = 01-0B,

Case 2 (I extracted the tag):

DA = 01-80-C2-00-00-00, SA = 00-02-7D-71-B8-C1, Length = 00-40, LSAP =

42-42, CTRL = 03,

I knew the multicast DA of the case 2, but not the multicast DA of the cas 1. Do you know the difference?

Best regards, Michelot

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It seems it is specific to the STP version of Cisco.

Best regards, Michelot

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