Re: threats ID

[Tim Shepard <shep@alum.mit.edu>]

> There is no such thing as layer 3.5.
> 
> Network layer solutions are at layer 3, transport layer solutions are
> at layer 4. PERIOD.
> 

As far as I am aware, the IETF has never reached a consensus on how
the layers are to be numbered or what layers should exist.  Clearly
the number of layers varies depending on exactly what you are doing.
Note that IPSEC adds a layer, increasing the number of layers below
TCP by one.  (I would say that IPSEC looks like it is quite a bit more
than half a layer, and it certainly appears to be thicker than many
other things which are allowed to occupy a full unit of layering in
our minds.)

I know that many people are aware of the layer numbering convention
that was developed for the OSI suite of compter networking protocols,
but I know of no reason to take that particular numbering of layers
seriously. I have trouble keeping straight which layer is which
number, so I would appreciate it if layers would be refered to by some
meaningful name and not just a bare number.

What layer number you are at depends on where you start counting and
how many things you have stuck between you and there.

			-Tim Shepard
			 shep@alum.mit.edu