random thought: would piling 2 ethernet shields (one on top of another) on a Duemilanove work? i figure that it will need some hacking of the core libraries. i'm guessin there shouldn't be issues with power.
anyone tried that before?
Interesting idea:
It could work but you will have a hardware conflict on the SPI bus, so the upper shield should have the ChipSelect pin bend so it can be controlled from another pin. The library must be patched so that in the constructor the pin-number for the CS can be given.
Don't know what difficulties you will meet down this road but I hope you keep us informed.
What is your goal in mind: a firewall, intelligent repeater, ....?
There could well be an issue with power, if you're feeding it through the onboard voltage regulator on the Arduino. The Wiznet chip is a bit of a greedy beggar for current. Besides that and the already pointed out SPI conflicts, the ethernet shield is slow (around 4kB a second) and sticking two together isn't going to do the performance any favours.
Wrong tree for a router/firewall/repeater IMO.
great. ok i'll update this thread if i try this out. thanks all!
There's a known problem with Wiznet chips not properly releasing the MISO line when they're not selected. It's the reason that the SD socket on the original Ethernet shields don't work.
Some people have come up with workarounds for this. A forum search should turn up their postings.
NKC has an Ethernet shield designed to make it easier to get it working with the Mega (which has a different SPI pinout). It might also make it easier to get two shields working together.