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Re: Waste will kill ipv6 too


From: Owen DeLong <owen () delong com>
Date: Fri, 29 Dec 2017 07:56:26 -0800



On Dec 29, 2017, at 02:27, sthaug () nethelp no wrote:

My wild guess is if we'd just waited a little bit longer to formalize
IPng we'd've more seriously considered variable length addressing with
a byte indicating how many octets in the address even if only 2
lengths were immediately implemented (4 and 16.)

Actually, that got heaved over the side fairly early in the IPng discussion,
because nobody  who was building silicon last century wanted to
deal with arbitrary-length addresses.  The IPv4 header had source and
destination addresses on 4-byte boundaries for good reasons which
still held true when we did the IPv6 headers.

It's rather interesting how parsing of variable length addresses was
thought to be way too complicated - while parsing of IPv6 extension
header chains of unknown length was okay.

Well... first, fast routers mostly don’t parse those chains. Second, to the extent they do, it’s the biggest legitimate 
complaint I’ve seen with the design of IPv6. 

Owen


Steinar Haug, Nethelp consulting, sthaug () nethelp no


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