Dale, Ethertypes are allocated not by IANA, but IEEE. See https://standards.ieee.org/develop/regauth/ethertype/ for further information.
Cheers, Andy On Sat, Jul 22, 2017 at 4:15 AM, Dale R. Worley <[email protected]> wrote: > The concept of Geneve as a generalized encapsulation technique -- or > even the concept of some alternative to Geneve as a generalized > encapsulation technique -- brings very little overhead other than > demands on number assignments. This message is an exercise to work > through the implications of that idea. > > When Geneve is used over layer 4, UDP, then there needs to be an > assigned UDP destination port. IANA has assigned 6081 as the port > number. > > When Geneve is used over layer 3, IP, it needs a protocol/next header > value. Protocol values are only 8 bits, but only a bit over half of the > space has been allocated in 30 years, so it seems that there's not a lot > of pressure on the number-space. > > When Geneve is used over layer 2, Ethernet, it needs an Ethertype > value. But only 3,500 Ethertypes have been assigned out of a space of > 64k. > > In theory, Geneve could be used over layer 1, in which case the > underlying protocol doesn't have a next-protocol field, but rather the > layer 2 protocol is configured by the operational environment > > The Geneve header contains a next-protocol field, which is an Ethertype, > which signals the overlying protocol. > > When layer 2 is used over Geneve, the next-protocol is 6558 > (encapsulated Ethernet). > > When layer 3 is used over Geneve, the next-protocol is 0800 (IPv4) or > 86DD (IPv6). > > When layer 4 is used over Geneve, things are more complicated, because > there's no defined way of representing an IP protocol/next header value > directly as an Ethertype, and few or no protocols that can be > represented as such a value have assigned Ethertypes. > > It seems to me that it would be useful to embed the IP protocol/next > header value space into the Ethertype space by allocating a block of 256 > Ethertypes, xx00 to xxFF, to IANA, to represent the protocol/next header > values. This is a large allocation, but the Ethertype space is thinly > allocated and ony 60 or so of the possible first-byte values are used, > leaving over 150 choices to allocate. > > Thus, if we are to generalize Geneve (or any similar protocol) to be > used over and under various protocol layers, we need these additional > IANA assignments: > > - a protocol/next header value to indicate Geneve > > - an Ethertype to indicate Geneve > > - a 256-value block of Ethertypes that are assigned to IANA to embed the > protocol/next header value space > > Comments? > > Dale > > _______________________________________________ > nvo3 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nvo3 >
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