Diffrences: IPv4 vs IPv6

Robert E. Seastrom rs at seastrom.com
Wed Jan 25 12:14:21 CST 2012

Andre Kesteloot <andre.kesteloot at verizon.net> writes:

> http://electronicdesign.com/article/embedded/What-Is-The-Difference-Between-IPv4-and-IPv6.aspx?cid=embedded_newsletter&NL=1&YM_

This article has a bunch of factual errors.  My favorite:

   6rd (IPv6 rapid deployment) uses IPv6 to bridge IPv4 subnets. It
   tunnels IPv4 packet over IPv6. It is sometimes a service provided by

Actually it's the other way around.  6rd is "private 6to4" and allows
delivery of IPv6 over access networks that only speak IPv4.

Completely ignored when he talked about transition mechanisms were
NAT64/DNS64 and DS-Lite, both of which are likely transition points as
we go to lessen the load on carrier-grade NAT equipment (which is
going to be a total flying circus).

I also like "ipsec: required" in his side-by-side comparison.
Pervasive IPsec under IPv6 is aspirational-not-operational.

Then there's this one:

   "There is just one IPv6 private address block. It is fc00::/7, also
   called a Unique Local Address. The specification works just like the
   one used with IPv4. This means the block uses 121-bits for local

which suggests that the author is kind of unclear on the subject (you
should choose a network prefix at random out of ULA space and subnet a
/64 for "local devices" just like any other network, and please don't
repeat either the "" or the "192.168.1/24" errors that
people make when setting up private networks - the latter is why I
fought (in vain) for ULA-Central addresses).

The author is making a good effort to explain the technology based on
what he's read, but you should confirm what you read in this article
with an SME with a bit of street fighting experience.  :)

mo, what's your favorite?  Maybe an IPv6 preso for AMRAD is called for...


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