Talk:EtherType
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[edit] Ethernet II Prevalence
I seriously doubt that e.g. 802.3 is "the way we do IP traffic today" as was implied by this article prior to my changes. AFAIK Ethernet Version 2 is and remains the way most Internet Protocol networks are set up.
I do understand that the IEEE most dearly would like 802.3 to be used instead of Ethernet Version 2, and as writers of textbooks and the like tend to listen to people with big mouths they readily sometimes believe that 802.3 is a common protocol. It is not. Ethernet Version 2 is very very common though. It is the default behaviour of e.g. Microsoft Windows and Linux to use Ethernet Version 2.
Prove me wrong - empirically.
[edit] 802.3 Compatibility
Taken from other 802.3 twiki: IEEE 802.3x-1997 allows the 16-bit field after the MAC addresses to be used as a type field or a length field, so that Ethernet II frames are also valid 802.3 frames in 802.3x-1997 and later versions of the IEEE 802.3 Ethernet standard.
[edit] EtherType Database
I work as a technical consultant to the IEEE Registration Authority for evaluating new EtherType assignments. At the recent July 07 meeting of the IEEE Registration Authority Committee (RAC), we had a long discussion about the poor quality of information about existing EtherType assignments in the IEEE's public EtherType listing. They decided NOT to undertake a project within the IEEE to update and expand the information content in their EtherType public listing, and instead I was instructed to contact Wikipedia about the possibility that they should host the definitive list of EtherType assignments.
The fundamental problem is that the IEEE listing is basically just a transaction log showing who made the request for each assigned EtherType, without attempting to track who is currently responsible for maintaining the protocol. As a result: (1) there is very little information about long-standing EtherType assignments (that happened before the responsibility for EtherType assignments shifted from Xerox to the IEEE); and (2) it is difficult to determine what protocol belongs to each EtherType, even for well-known protocols defined by IEEE and/or IETF standards. For example, the EtherType value 0x8808 is used for the MAC Control Frames as defined in 802.3x-1997, but the IEEE public EtherType listing says it belongs to Bay Networks with ``protocol unavailable. OTOH, at least you can find the EtherType by looking it up in the Ethernet standard (IEEE Std 802.3-2005, clause 31.4.1.3).
The situation is much worse for IETF standards, because the RFC documents don't get edited to include the EtherType value after it has been assigned. For example, the definition of ARP in RFC 826 (aka STD0037) does not include EtherType value 0x0806, but merely refers to it mnemonically as ``ether_type$ADDRESS_RESOLUTION. Although the EtherType value for ARP was listed in RFC 1700, that document was obsoleted by RFC 3232 moving the responsibility for assigned numbers to an online repository at IANA -- which for EtherTypes points to the IEEE public listing which does not mention ARP, and says that 0x0806 belongs to Symbolics, Inc. with "protocol unavailable".
So the bottom line is, can we rely on the Wikipedia entry for EtherTypes to be used as the definitive reference for the usage of existing EtherType values? I would work to make sure sure that all entries for IEEE protocols are complete and up-to-date, and would ask the IETF to do the same for their protocols. I can also ask that the applicant for each newly-assigned EtherType value take responsibility for maintaining their own entry. Does this make sense? Comments please! DrBLAM 22:20, 30 July 2007 (UTC)
