[En-Nut-Discussion] Finally change ...emergency system

Vesa Jääskeläinen chaac at nic.fi
Fri Jun 27 18:15:07 CEST 2008

huys cobb wrote:
> Thank's
> Thiago A. Correa wrote:
>> Wouldn't this require NAT? I don't think Ethernut has any routing mechanisms
>> inplace, in order to transfer packets from one IP based interface to
>> another.
> Nowadays the GSM modules had PPP TCP/IP stack..and had capability became server side...I'm using SIM300 and ethernut v1.3g
> There was discussion about that at:
> http://www.edaboard.com/ftopic176890.html
> So..I think that the ethernut can ber used as GPRS/PPPd GSM network gateway to ethernet.

Well... PPP will provide IPv4 nicely for you, but rest you have to 
"invent". That is the hard part. And that is the code that you usually 
have to pay some $$$'s for.

What you really want to do is to implement NAT. Ethernut at least with 
AVR will not give too high performance for you in this scenario.

> Vesa J wrote:
>>> The GSM module had PPP stack...
>>> And the ethernut as gateway from GSM network to Ethernet side...
>>> Someone here had info about how to made pppd from GSM network >to ethernet via >>ethernut.
>> Buy a 3G/GPRS router... it has everything you need. And in the end costs 
>> less.
>> At least Linksys and D-link has one of those...
> Yes,there was but have two reasons:
> 1.I had hardwares already and didn't had moneys to purchase
> 2.The gadget from Linksys and D-link can only work for US operators.(When I saw the brochure).

Well the trick is to put proper pc-card there that matches your region.

In example following models might work for you:
D-Link DIR-451 - http://www.dlink.com/products/?sec=1&pid=525

This US-page only lists US possibilities, but for local D-link homepage 
there are other options visible.

Compatible Internet PC Cards (freely edited):

- Huawei E220 (USB)
- Huawei E630
- Vodafone GT MAX GX0201
- Option GI 0201 (USB)
- Novatel Wireless Merlin U530
- Novatel Wireless Merlin U730
- Option Wireless GT 3G Quad
- Sierra Wireless AirCard 860
- Sony Ericsson GC89

Doing whole stuff form scratch, even with PPP outputting 3G device there 
is sill lots of work to be done to be success. If you want to do home 
brew version, you may want to use PC and Linux and then compatible 3G 
adapter. Even that includes some work, but is doable for couple of days.

Hardest part in this project would be NAT functionality (or 
alternatively you can implement HTTP proxy or so, but this limits 
usage). And next thing is to have proper performance.

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