Re: threats ID

[Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>]

Brian;

> Masataka, you conclude by saying
>
>
> > However, TCP is not IP, which is the point of my presentation
> > at Vienna.
>
>
> We can hardly disagree. But TCP is not SCTP, UDP, DCCP or ICMP either.

That's why TCP is not IP.

> The systems level argument for a layer 3.5 solution

There is no such thing as layer 3.5.

Network layer solutions are at layer 3, transport layer solutions are
at layer 4. PERIOD.

> is that it can cover
> all cases, including ones we have not invented yet.

UDP, which we already invented, can not be covered by network
layer solutions.

> You are correct that a layer 3.5 solution requires cached state, probably
> with timeouts

Anything with wrongly guessed timeout is no solution.

> There is a classical
> solution to that, which is for the ULP to send a keepalive signal to prevent
> the cache from timing out.

That is a modification to the ULP, including application ones and
is substantial.

That you must modify something above layer 4 gives a very convincing
evidence, even for those who don't understand layering enough to dream
of layer 3.5, that layer 3.5 is a fallacy.

> That would indeed be a ULP enhancement, but a very
> minor one and not essential.

That is a well known argument for NAT.

However, it is not an enhancement but a restriction.

It is the essential reason why NAT is not acceptable.

							Masataka Ohta