Re: [Fwd: I-D Action: draft-carpenter-6man-why64-00.txt]

Hi,

----- Original Message -----
> From: Christian Huitema <huitema@microsoft.com>
> To: Brian E Carpenter <brian.e.carpenter@gmail.com>; Alexandru Petrescu <alexandru.petrescu@gmail.com>
> Cc: "ipv6@ietf.org" <ipv6@ietf.org>
> Sent: Friday, 17 January 2014 4:47 PM
> Subject: RE: [Fwd: I-D Action: draft-carpenter-6man-why64-00.txt]
> 
> 
>>  But maybe someone who has Christian's book could send a paraphrase
>>  of his explanation.
> 
> I have of course a few copies on my shelves. Mark ZZZ Smith is probably 
> referring to the Chapter 4 of "IPv6, the new Internet Protocol," which 
> was published in 1996.

The edition I have is the 1998 2nd edition, and the text which I found most interesting regarding the history of the address size choice was in the Points of Controversy section, starting on page 77, of the "Routing and Addressing" chapter, which described considerations such as geographic based addressing, variable length addressing and the 8+8 proposal.

I'd still recommend people get the book even though it was last published in 1998, because the "Points of Controversy" sections at the end of each chapter provide so much insight into why IPv6 was designed the way it was. I've found the "whys" and "why nots" of the designs of things to be as useful if not sometimes more useful than the "whats", and this is one of the few networking books that I have that captures quite a lot of the "whys". (Radia Perlman's "Interconnections", 2nd edition is another one.)

Regards,
Mark.

> The chapter deals with "plug and play," and the 
> first paragraph reads:
> 
> "By the end of June 1994, the IPng saga was coming to a close. The IPng 
> selection committee had almost made up its' mind. The choice had to be based 
> on the SIPP proposal, but SIPP could not be bought lock, stock, and barrel. A 
> substantial number of directorate members thought that the 64-bit addresses were 
> too narrow, that they would not provide enough flexibility to implement proper 
> routing protocols. There was a compromise in sight, if only the SIPP proponents 
> would agree to increase the address size to 128 bits. The IETF decision process 
> is based on building consensus, part of which implies polling opinion leaders. I 
> was one of those leaders by this time, or so they thought, so they polled me. 
> Would I accept inflating the address to 128 bits? I had publicly stated many 
> times that 64 bits was more than enough and I could back my opinion with 
> substantial mathematical analysis. However, I did not hesitate too long. Going 
> to 128 bits was a little price to pay to reach consensus and sa
> ve the Internet. Moreover, 128-bit addresses have a definite advantage. They 
> have twice the width that routing procedures require, hence they make a lot of 
> room avail-able for proper implementation of auto configuration procedures. 
> "
> 
> I then go on to explain how auto configuration works by concatenation of a 
> network prefix and a unique identifier of the host, normally a MAC address. The 
> 1996 version of the book was written before the ND specifications was finalized, 
> and does not actually specify the 64 bit prefix size. Many examples show an 80 
> bit prefix and a 48 bit MAC address.
> 
> 
> -- Christian Huitema
> 
> 
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