IPv4 address length technical design

[james.cutler at consultant.com (Cutler James R)]

On Oct 4, 2012, at 4:00 PM, William Herrin <bill at herrin.us> wrote:
> On Wed, Oct 3, 2012 at 7:12 PM, Cutler James R
> <james.cutler at consultant.com> wrote:
>> On Oct 3, 2012, at 6:49 PM, Jimmy Hess <mysidia at gmail.com> wrote:
>>> In 100 years, when we start to run out of IPv6 addresses,  possibly we
>>> will have learned our lesson and done  two things:
>>> 
>>> (1)   Stopped  mixing the Host identification and the Network
>>> identification into the same bit field;   instead  every packet gets a
>>> source network address,  destination network address, AND  an
>>> additional  tuple of       Source host address,   destination host
>>> address;  residing in completely separate address spaces,  with  no
>>> "Netmasks",  "Prefix lengths", or other comingling of  network
>>> addresses and host address spaces.
>>> 
>>> And
>>> (2)  The new protocol will use  variable-length address for the Host
>>> portion, such as  used in the addresses of CLNP,  with a convention of
>>> a specified length,  instead of a hardwired specific limit  that comes
>>> from using a permanently  fixed-width field.
>> 
>> I suggest that the DNS name space should be considered to be
>> an "hierarchical host address space" thus satisfying (1) and making (2) moot.
> 
> I'd suggest that too, but we'd have to throw out TCP, UDP and a good
> chunk of the BSD sockets API to get there.
> 
> Or did you mean use DNS as it fits in the current system, which
> doesn't actually satisfy (1) at all since the layer 4 protocols
> continue to build the connection identity from the layer 3 network
> identity instead of the external host/service identity.
> 
> Regards,
> Bill Herrin

Yes. 

Why does the connection identity have to include the host identifier.  Is that not a problem under the control of applications?