In the 1970s, Bob Metcalfe and David Boggs invented Ethernet while working at Xerox PARC. At that time, Ethernet's top speed was 3 Megabits per second (Mbps). This version was installed in a few sites including Boeing, the White House, and various academic institutions. In the early 1980s, the original Ethernet standard was drafted by Digital Equipment Corporation (DEC), Intel, and Xerox and adopted by the IEEE as the 802.3 standard. Ethernet has become the dominant Local Area Network (LAN) Architecture (Kadambi, Crayford, & Kalkunte, 1998).
Why Not Token Ring?
The decision to move from Token Ring to Ethernet is not necessarily based on the technical merits of Ethernet. Although Ethernet has been tremendously successful, there are many technical reasons for using Token Ring. Since the technology is based on a physical star architecture similar to Ethernet, Token Ring networks are able to repair themselves if a node is taken offline. Additionally, since each node has predetermined access to the network, the technology is useful in environments were frequent transactions are the norm. Finally, the introduction of 100 Mbps and promise of 1000 Mbps Token Ring have made speed a non-issue. The primary for moving from Ethernet to Token Ring is cost. IBM originally developed the Token Ring standard and holds patents on much of the technology. Even with licensing agreements in place, this means that only a few vendors produce Token Ring equipment. Fewer vendors mean higher costs (Walters, 2001).
Companies deploy Ethernet networks for three primary reasons. As we have discussed, the first is cost. Since it is not encumbered by patents and licensing issues like Token Ring, Ethernet equipment is produced by a wide range of vendors. The competition among vendors results in higher quality and lower prices. Ethernet equipment is a standard part of nearly every computer that is produced today. The speed of Ethernet is also attractive to network implementers. With 1000 Mbps speeds being deployed to the desktop, the availability of 10 Gigabits per second (Gbps) is alluring. Finally, Ethernet networks are simple to manage. The technology was designed to operate without management. Any additional management or monitoring implemented by network operators is only necessary to improve performance (Kadambi, Crayford, & Kalkunte, 1998).
Three kinds of equipment are necessary to operate an Ethernet network. Each node connected to the Ethernet network must have an Ethernet controller. This includes computers, such as desktops and servers, as well as networked devices such as routers or printers. In the middle of all these networked devices is an aggregation point such as a hub or switch. Hubs and switches allow the devices connected to them to communicate. Finally, networked devices are connected to hubs and switches via cabling. Each Ethernet standard requires a minimum cable type to guarantee error-free communication.
Converting the network from Token Ring to Ethernet can be a fairly simple process. The first step is to plan the address scheme. If there is an existing Ethernet network that the Token Ring network is going to be migrated onto, an address scheme is already in place. Otherwise, if the Dynamic Host Configuration Protocol (DHCP) is going to be used, then a DHCP server should be made ready for the conversion. The key to the migration is the building wiring. Token Ring was originally designed to operate over Shielded Twisted Pair (STP) cable rather than the Unshielded Twisted Pair (UTP) typically employed in an Ethernet network. Fortunately, Ethernet has been certified by IBM and Cisco to operate over STP (Cisco, n.d.). Once the cabling is verified to work with Ethernet, the necessary switches must be put into place alongside the existing Token Ring hubs. The final step in the process is to install Ethernet controllers into each machine that will be migrated. Since the switches are already in place, computers can be migrated one at a time rather than in large groups. This makes the transition much easier.
Cisco Systems, Inc. (n.d.). Token Ring-to-Ethernet Migration. Retrieved September 11, 2009.
Walters, E. G. (2001). The essential guide to computing: The story of information technology. Upper Saddle River, NJ: Prentice Hall PTR.
Kadambi, J., Crayford, I., & Kalkunte, M. (1998). Gigabit Ethernet: migrating to high bandwidth LANs. Upper Saddle River, NJ: Prentice Hall PTR.