• TCP/IP
• Packet Radio
• EDI
• Telephone
• Ethernet

• Virtual Private Networking

See also:

• The Network Administrators Guide by Olaf Kirch
• http://members.tripod.com/~mdileo/ Tiny Embedded Network
• http://www.elmelectronics.com/
• MODBUS
  • Full reference to MODBUS including source code.
• LON
  • peer-to-peer serial protocol. It supports heirarchical addressing (scalable up to 32K nodes in a logical network), multi-drop, multiple media - twisted pair, RF, Fiber, powerline (or a mix of media in a logical network). Since it is peer-to-peer, every node can act as a master or you can implement a mult-master architecture. The protocol is done and implemented in silicon available from multiple sources. Echelon wants to charge $5 per node (!) for use and restricts doc's/changes spec to enforce this.
• CAN
  • http://www.llp.fu-berlin.de/pool/newproj/CAN/ can4linux is a driver supporting 82c200 and 82527 based CAN controllers,