Re: Ether types (was: Re: GRE specification going to last call)

[David Meyer <dmm@cisco.com>]

> > 
> > "The IANA SHOULD NOT encourage the assignment of additional ETHER
> > TYPES (GRE Protocol Types) for use with GRE."


> Two issues.
> 
> Firstly, why should it matter whether IANA (or anyone else) assigns 
> *additional* ether types or not? This should not affect any existing systems.
> 
> Secondly, I'm a little confused and/or ignorant about what exactly "DIX 
> ether types" are and who is authoritative for them.
> 
> RFC2074 (for example), in the ether2 PROTOCOL-IDENTIFIER section says: "DIX 
> Ethernet, also called Ethernet-II... The authoritative list of Ether Type 
> values is identified by the URL: 
> ftp://ftp.isi.edu/in-notes/iana/assaignments/ethernet-numbers."
> 
> http://www.cavebear.com/CaveBear/EtherNet/ (last updated 1998/04) (cited by 
> "ethernet-numbers") says "The Ethernet Type values are managed by Xerox" 
> but also lists "contributions from network managers and vendors" and has a 
> reference to the rather ancient RFC1010.
> 
> RFC1701 says "In general, the value will be the Ethernet protocol type 
> field for the packet. Additional values may be defined in other documents." 
> It then gives a list of types, the only ones which conflict with 
> "ethernet-numbers" are those below 05DC i.e. SNA, OSI, and PUP.  It also 
> says "Future protocol types must be taken from DIX ethernet encoding... See 
> the IANA list of Ether Types for the complete list of these values." Is 
> this an indirect statement that "ethernet-numbers" is the definitive DIX 
> encoding?
> 
> The new "gre-update-02" notes "XEROX" and references (the old) RFC1700, 
> which does not assign authority, but says you should contact XEROX for an 
> ether type.
> 
> The "ethernet-numbers" document itself says "The following list of 
> EtherTypes is contributed unverified information from various sources." Not 
> a very strong assertion of authority. It also says you should contact the 
> IEEE Registration Authority if you want an ether type.
> 
> http://standards.ieee.org/regauth/ethertype/type-tut.html asserts "the 
> value of the type field is obtained from the IEEE Type Field Registrar. New 
> values obtained from the IEEE Type Field Registrar will not interfere with 
> the existing Type field assignments from Xerox or the IEEE. Former 
> assignments are still valid." Whether this is authoritative or not I can't 
> say, but it's certainly the most assertive statement I've found on the topic.
> 
> But the IEEE don't seem very forthcoming. They state "It is important to 
> realize that this is a partial listing of all assigned EtherType Field. Not 
> all recipients wish to publish their assignment at this time." The actual 
> list of public assignments is at 
> http://standards.ieee.org/regauth/ethertype/type-pub.html
> But this only lists the organizations to which assignments has been made, 
> e.g. "0800-0803" (including 0800 for IPv4) is listed simply as "Xerox". 
> Also "86DD" (IPv6) is not listed here at all, but is of course listed in 
> "ethernet-numbers". This may be because it was a "secret" assignment, but 
> it sounds unlikely since it came from IANA.
> 
> Any answers?
> 
> As for GRE, can't we just say (words to the effect) "use what was in 
> [RFC1701] and what is in [ethernet-numbers]" and remove the section about 
> "NOT encourage"?
> 

	I removed it. Thanks.

	Dave