> Somewhere along the way, it was decided that a 128 bit address was > more appropriate - if 32 bits isn't enough for all uses for all time, > who says 64 is? Long story there that I wasn't a party to.
That was actually decided during the review of the SIPP proposal, and was pretty much a condition for selecting SIPP (and 128 bits) as IPv6. > But OK, it > became 128 bits, and someone started talking about maybe using the > MAC address in the host part. Part of same review. SIPP was competing for selection with TUBA, a proposal based on CLNP. CLNP (i.e. the OSI datagram layer) used variable length addresses, but the most prominent form featured 20 bytes addresses whose last 48 bits where derived from the 48 bit Ethernet address of the host. That allowed for auto-configuration, much like IPX. Auto-configuration based on MAC address was pretty much part of the initial deal, the rationale for moving from 64 to 128 bit. "Someone" was really many people, but if I had to pick a name I would say Scott Bradner. > Someone noted that not all MAC > addresses were 48 bits; for example, an E.164 address (a telephone > number by any other name) when represented as BCD digits might easily > be 16 digits, and some 802 series addresses are 64 bits. So it was > suggested that 64 bits be set aside for the host part. That was, and still is, the official IEEE line. IEEE 802 is very concerned that 48 bit is not quite enough. -- Christian Huitema -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
