Re: [uCsimm] net traffic filtering

From: Tom Walsh (tom@cyberiansoftware.com)
Date: Tue Jan 16 2001 - 11:46:32 EST


daniel haensse wrote:
>
> Most of the filtering is done by the ethernet controller (if it is not running
> in promiscuous mode), since only packets with matching ip destination
> will be received and afterward processed by the up. If you want to do some
> routing, I would suggest to use a 68vz328 which can
> run with up to 33MHz.

I tend to agree with Daniel, the EZ is not a performance platform, it
does have its place. You will have to place the ethernet controller
into promiscuous mode, then write code that will take all traffic that
is intercepted, examine the packet headers, and decide how to process
them. If you are trying to shove the data down a serial port to be
processed by another machine, then you will have to keep your overhead
low. Or if you simply want to print out the to: from: addresses of the
matching IP and don't care what the data is, then the EZ would be able
to do that for you.

Actually, if you need another platform to build this upon, take a look
at what Erwin has at: 'http://uclinux.home.at'. He is working with the
ARM7TDMI and I would venture to say that the ARM processor he is using
is still a higher performance than what you can get out of the VZ
processor. The VZ only 5 MIPS, I do believe that the ARM7TDMI is
somewhere around 20 MIPS. There are evaluation boards that will cost
you several hundred US dollars, compared with the 600..1000 US dollar
cost for some of the Motorola evaluation boards, these ARM boards might
be a better choice: more MIPS, less cost, but may not be exactly what
you want as they may have too little RAM, missing Ethernet interface,
etc.

This all depends on your level of expertise. If the hardware is
missing, I personally would add it, I design stuff. But if you are an
end-user and not an engineer (yet), you may have to spend a significant
amount of money to get the system that will do your job. Just remember
you can always waste excess MIPS, if the board does not have them to
give you then will not be able to get the job done. When in doubt,
overpower the system (more MIPS).

Regards,

TomW

-- 
Tom Walsh - WN3L - Embedded Systems Consultant
'www.openhardware.net', 'www.cyberiansoftware.com'
"Windows? No thanks, I have work to do..."
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