Re: Port numbers in the network layer?

Am 25.04.2013 14:52, schrieb John Day:
> Re: [e2e] Port numbers in the network layer?
> The question is why is a protocol-id field required in some protocols 
> and not others.
>
> If it is to identify the protocol in the layer above, then how many 
> thousand SCTP instances can I identify on top of a single IP 
> instance.  If it identifies the protocol, then that should be 
> possible.  Obviously it isn't what it is intended for.

So, what is, concisely, the problem and your proposed solution?

Up to know, each individual TCP connection is uniquely identified by an 
address quadruple (node 1, port 1, node 2, port2).

Why doesn't this work?

And which solution works better?