Well technically you are right, but you are still wrong :-0
I know you can get IPv4 on a controller. But I think you will need more than
1kB for IPv6 since IPSEC is required... And IPSEC requires public key on the
controller.
Yes there are bigger processors, but what I am interested in doing is putting
the processor into a light socket base. And to get the larger RAM you need to
get more pins (!). I was reading spec sheets over the weekend.
And the other issue is power. The larger, ethernet capable chips require a lot
more power. The tiny 384 byte RAM chips draw 11 micro-Watt. Which comes out at
half kilowatt hour in a millennia.
And yes, you can do IP in 1Kb ROM. But I need that for my cryptography. So far
I have found Skipjack in PIC logic but no code for AES yet. I am trying to
decide if Skipjack is enough for my application (controlling the garage door
from the Internet) or whether to code up the AES. Looks to me as if AES-128
should be practical.
The point I was making is that we are not going to have IP all the way out to
the edge of the network. However fast logic controllers get, the earlier
generation gets cheaper and is pushed out to another level.
And even if they can run IP they are not going to run the firewalls and such
that you would want to put the device out naked on the network?
But even without IP out to the edge, I can use the DNS to name them. And that
is all that matters to count them as part of the Internet. I can even assign
them a globally routable IPv6 address. But the device itself will never see it.
-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org on behalf of
michael(_dot_)dillon(_at_)bt(_dot_)com
Sent: Mon 12/1/2008 9:43 AM
To: ietf(_at_)ietf(_dot_)org
Subject: RE: The internet architecture
I know IETF thinks IP is the center of the universe and the
one true religion. But not in process control it is not. A
PIC controller comes with 384 bytes (BYTES, not kilo) of RAM.
This is wildly out of date. For at least the last 10 years
cheap and common PICs have been made with more RAM than that.
The IP stack has been implemented in 1K bytes of code that
will run on the 8-bit PIC CPUs.
Good luck getting an IP stack in there. And even if you use a
bigger processor with a built in TCP/IP stack you can only
run it over Ethernet type media. You can't use RS485 which
looks a much better bet for hardwired home automation systems
to me, it is what process control has used for decades.
Exactly. Process control doesn't need IP at all at the
edge of their network. They have other solutions that
work well for them. Whether it is I2C or one-wire or
RS-485, data can be relayed onto an IP network by devices
which speak both protocols. There is no problem here.
--Michael Dillon
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