On Tue, Sep 04, 2001 at 07:43:33AM -0500, Dale Botkin wrote:
> On Tue, 4 Sep 2001, Byron A Jeff wrote:
>
[ Agreement on IP and TCP complexity ... ]

> > I believe that the appropriate transport protocol is UDP. With its paper thin
> > wrapping over the core IP protocol, and its standard and widely deployed API
> > interface, it's perfect for a PIC to interact on the Internet.
>
> UDP definitely is a lot simpler to implement.  Once you have IP/UDP sorted
> out, you have the use of DNS, SNMP, and other very useful protocols.  The
> only real down side is that most firewalls will summarily deny UDP, so
> it's commercial applications are a little limited for some products.

That sucks...

>
> > My students and I have been working on and off on a UDP/IP/SLIP stack with
> > a linux gateway interface. The interface box is simply to allow for SLIP to
> > be used. Since SLIP is basically a trivial wrapper over IP, it's real easy
> > to implement and test on the PIC.
>
> Here's where I have a problem with most existing stacks.  SLIP is OK for
> something that will be connected to a dedicated box - like directly wired
> to a Linux machine's serial port, for example.

Which happened to be my target. Running completely in a vacuum wasn't a
requirement.

>  But for applications that
> will need Internet dialup connectivity, PPP is pretty much a requirement I
> would think.

Absolutely.

> Actually I'd be much happier with Ethernet, but there you
> have a requirement for either an ISA bus card (endangered species) or lots
> of surface mount and some magnetics.  I have a couple of stalled projects
> because I just haven't found a really good solution for this issue - but
> then I work with a peculiar set of restrictions, so this is not a problem
> for a lot of people.

I still think that parallel port cards may have some promise. But they too are
endangered. USB has quite a bit of complexity, especially at high speeds.

If you're not doing straight serial, there are definitely some dilimmas.

>
> I've also spent a lot of time writing a "bulletproof" modem dialer, one
> that will be able to handle redials, busies, no-answers, modem hangs, etc.
> It's NOT pretty and takes an awful lot of code space as it is.  One of
> these days I need to rip it completely apart and start from scratch.

How about a cell phone packet interface? More costly but maybe doable???

BAJ

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