AVR-Chat

I need to have up to 100 AVRs talk to each other over unknown topology 
network with long wires. collisions expected.
TWI can handle this nicely other than the long wire spec.
philips makes a I2C extender part that basically gives SCK & SDA a 
boost to allow low pullup R's to work. the driver has ~30mA drive and 
allows a pullup of 330 ohms - now if I reduce the speed, things "could" 
work well.
the mega8 data sheet is not totally clear if the low drive when TWI is 
turned on is a standard port pin capability, or a much reduced (3mA) 
drive, it does say it is slew limited. the other thing that is not 
obvious is if I can use the internal port pin pullup as the I2C pullup 
between the AVR and the extender chip as that "network" is actually 
point-point over no real distance. (the bad network is on the other 
side of the driver)

what I am really asking is if I really need the driver?

anyone experimented?