Many of the old DOS / early Win95 games utilizes the IPX protocol for multiplayer.An example of this is the game: Carmageddon and Red Alert 2
Inter Packet Exchange (IPX) has long been deprecated in favor of TCP/IP, meaning that it is somewhat hard to get old games to play on modern PCs - even PCs running Windows XP.
Although Windows XP does support IPX natively, getting games to run using this protocol is hard on modernish hardware - in any case, I have never really succeeded.
Lucky for us, IPX wrapper exists that wraps IPX packets in UDP broadcast packets meaning that the game/application talks IPX but using UDP as a Network layer protocol.
IPXWrapper by Solemn is exactly this, a wrapper for many of the old games: http://www.solemnwarning.net/ipxwrapper/
I recently tested this out using Carmageddon, a racing game from 97’ against a couple of friends in a LAN setup. Just copy over the dlls into the game directory and the game will load these dlls instead of using the ones coming with Windows and will thus use UDP as Network layer packet transport.
Wonderful workaround to deprecation!