[SGVLUG] Bit order (was Linux based web-server appliance)

[Dustin Laurence]

On Tue, May 23, 2006 at 03:47:45PM -0700, David Lawyer wrote:

> If there wasn't a physical layer, nothing could go over the internet.
> We a just wasting time quibbling over semantics :-)

You are missing the point--the semantics are very clear and inherent in
the whole reason for designing the Internet Protocol, and it does no
good to try to make up your own.  It's reason for existence is
*precisely* that it does not assume anything about any physical layer,
not even that it is based on binary data (it could send in some other
base and re-translate and IP wouldn't care).  All IP needs is that in
some way it can hand a packet of *bytes* to the next network.  Then IP
takes care of network-to-network addressing and routing no matter what
happens machine to machine.

In other words, there is *NO* physical layer in the Internet Protocol,
it's point is not to have one.  We use one to give IP what it needs,
that's all, but those layers are not part of IP.

> > You assumed that something related to modems was predictive of real
> > networking?!?
> 
> Not exactly, but I suspected it was true.

Then you were missing the crucial piece of political information--the
companies that defined the networking protocols back when PC's were
somewhere between a joke and non-existent were all big-endian vendors.
:-)

Though the fact that things like Horner's rule are inherently big-endian
would have been obvious to the designers, and they may have regarded it
as an advantage since it's easy to implement in hardware.  Shift and
add, shift and add, shift and add.  Now that I think of it this is a
case where even the addition can be done by bitwise or since no carrying
is necessary (it's already reduced to canonical form).

Dustin

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