[TUHS] Research Datakit notes

[Rob Pike]

I am not a networking expert. I said that already. The issue could well be
a property more of sockets than TCP/IP itself, but having the switch do
some of the call validation and even maybe authentication (I'm not sure...)
sounds like it takes load off the host.

-rob


On Tue, Jun 28, 2022 at 8:39 PM Derek Fawcus <
dfawcus+lists-tuhs at employees.org> wrote:

> On Sun, Jun 26, 2022 at 09:57:17AM +1000, Rob Pike wrote:
> > One of the things we liked about Datakit was that the computer didn't
> have
> > to establish the connection before it could reject the call, unlike
> TCP/IP
> > where all validation happens after the connection is made.
>
> Nor does TCP, one can send a RST to a SYN, and reject the call before it is
> established.  That would then look to the caller just like a non listening
> endpoint, unless one added data with the RST.
>
> So this is really just a consequence of the sockets API, and the current
> implementations.
> I've a vague recall of folks suggesting ways to expose that facility via
> the sockets
> layer, possibly using setsockopt(), but don't know if anyone ever did it.
>
> As I recall that TCP capability was actually exposed via the TLI/XTI API,
> and (for some STREAMS based TCP stacks) it did function. Although I may be
> thinking of embedded STREAMS TCP stacks, not unix based stacks.
>
> Or by 'connection' are you referring to an end-to-end packet delivery,
> and that Datakit allowed a closer switch to reject a call before the packet
> got to the far end?
>
> DF
>
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