by SpineyNorman » Aug 19th, '05, 13:48
"From the very first PS2 up to about version 8 or so, they all had a firewire port built in that was intended for connecting consoles together for local multiplayer. Only a couple games supported system link via ilink (most notables: GT3, Timesplitters 2, Time Crisis 3). In mid-2003, someone at Sony realized that the likelihood of two PS2s, two displays, two copies of the same game, and a $40 ilink cable all being in the same room was so unlikely that it would never become a selling point. Thus, they logically got rid of the ilink.
At this time the Network Adapter became bundled with the PS2, and they shifted multiplayer strategy to work over the internet. However this is still a good thing, because the Network Adapter can still allow LAN play, which is pretty much the same as system link (just over Ethernet cables). All you need is either a hub and a couple of straight through cables, or if you are just connecting two PS2s, a crossover cable."
Found this on agames forum. Hope it helps!