[ppml] 2005-1:Business Need for PI Assignments
Ed.Lewis at neustar.biz
Mon Apr 25 10:24:11 EDT 2005
At 16:11 +0100 4/22/05, Michael.Dillon at radianz.com wrote:
>IPv6 is not IPv4. Being prudent and conservative in an IPv6
>world involves different behaviors than being conservative
>in an IPv4 world.
Reading the further discussions bring me back to this statement.
I wonder what the differences are. I can think of some. When I hear
arguments about fractions of space available, I don't see why
fractions are relevant.
More and more, IPv4 and IPv6 seem alike to me. IPv6 only adds bits
to the address.
IPv6 promises a new generation of software to make all sorts of other
wonderful things happen - but as it's taken so long to get rolling,
it is now plagued by the same disease as IPv4 - hardening of the
software. E.g., renumbering IPv6 networks is impinged by firewall
rules - firewalls weren't around back when IPv6 design work began.
In addition, IPv4 has been accreting capability to come up to what
was wanted from IPv6. (E.g., NAT has extended the address space.)
A /32 of IPv4 space is the same percentage as a /32 of IPv6 space.
That's obvious. So what? With more address space available, I would
expect to get a smaller percentage of the overall space.
The one alleged feature of IPv6 that plays to the size of the
addresses and the amount assigned to a network is its "security
through obscurity" achieved by being sparse. I find it ironic that
folks will say that "because it takes so long to scan a network" the
net is more secure yet also say that "NAT provides no security." Not
that NAT provides security, but how is a wasting a lot of space to
hide a server any better?
The one pertinent difference is that devices are supposed to be
capable of having multiple addresses on an interface - for multicast
groups, etc. I can buy that you need to allocate more addresses than
interfaces, something not widely done in IPv4. This is a double
edged sword - scoped addressing isn't something generally beneficial
to applications. (Do I open the SSH session over a globally unique
address or the local scope address?)
What I'm afraid I am hearing is that "since there are so many more
IPv6 addresses, let's loosen the address supply to make it easier to
manage." That sounds a little like a cop out, understanding that the
technology is immature and we don't really know where it's heading.
If you put a /48 in my house, with each device getting a /64 to
assign a /128 to it's interfaces, I still have a hard time imagining
that this would be an efficient use of space. Even with MIT-like
smart kitchens, etc., I can't imagine that much address space being
needed and used efficiently. (Especially for those who've been to my
house. I could address all of the items in my fridge with a v4 /29,
maybe a /28 after a trip to Giant.)
It seems to me that IPv6 DHCP assigning addresses more compactly than
using the Ethernet address as the last 48 bits would be worth the
Edward Lewis +1-571-434-5468
If you knew what I was thinking, you'd understand what I was saying.
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