Subject: (no subject)

From: "Anjali Gajendragadkar" <[email-masked]>
Date: Tue, 18 Sep 2007 10:37:14 +0530

Conime,
> 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 p=
retty 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 add=
resses, 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 al=
lowed for auto-configuration, much like IPX. Auto-configuration based on MA=
C address was pretty much part of the initial deal, the rationale for movin=
g from 64 to 128 bit. "Someone" was really many people, but if I had to pic=
k 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

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