Understanding Communication Protocols: FDDI, Ethernet, Fast Ethernet and Token Ring

Computer networks are complex, involving multiple layers of hardware, software and protocols governing the transmission and reception of data. The network must simultaneously integrate many functions while maintaining compatibility of device connections. Network architecture is the name for the design principles that go into creating and building a computer network. Designing a network involves both logical and physical considerations.

Network architecture relies on different communication standards, or protocols, to connect the various devices on a network. Some of the most popular technologies include Ethernet, Fast Ethernet, token ring and Fiber Distributed Data Interface (FDDI). These technologies have made network interfacing and design more sophisticated. Using these technologies allows network architecture to build robust frameworks that transcend the limitations of old paradigms.

Ethernet

Ethernet consists of physical cabling and protocol standards that govern the transmission of data through the cabling. Basic Ethernet design involves all devices on a network communicating over a single cable. A local area technology, Ethernet works best connecting devices over very short distances.

A computer sending data along an Ethernet cable has to address it so the right device intercepts it. Every device reads a packet sent along an Ethernet channel, but only the device matching the address can use it. Ethernet has built-in collision detection, which protects the network from colliding packets. Additionally, Ethernet devices “listen” to the cable to make sure no other device is transmitting. It is like a reconnaissance team giving the all clear to proceed.

Fast Ethernet

The Ethernet design first created by Robert Meltcalfe at Xerox Corporation in 1973 could only support up to 10 megabits per second (Mbps). Fast Ethernet can transmit data at the rate of 100 Mbps. Fast Ethernet started to be deployed on a large scale in the 1990s when higher local area network (LAN) performance was needed by businesses. A major advantage of Fast Ethernet is the ability to coexist and integrate with existing installations. The result has been for most networks to include both Ethernet and Fast Ethernet. Using so-called “10/100” adapters is what makes this possible. The adapter detects whether the cable is Ethernet or Fast Ethernet and adjusts accordingly.

Token Ring

Developed by International Business Machines, token ring is a widely used alternative to Ethernet and Fast Ethernet. In contrast to the wait-and-see approach to data transmission used in Ethernet, token ring utilizes an orderly method of strict rules. Data is transmitted through a ring of computers, from device to device until it reaches its intended destination.

The transmission process occurs through a token, which is special permission given to a device to transmit. The token races around the ring of computers until it finds one that wants to transmit. The transmitting computer gets rid of the token, replacing it with a data frame which completes its own journey around the ring, returning to the transmitting computer. Finally, that computer removes the frame and creates a new token, which re-starts the process.

FDDI

FDDI is an optical communications standard, capable of transmitting data at the rate of 100 Mbps at a distance of up to 200 kilometers (around 127 miles). Network architectures that use FDDI serve thousands of end-users, linking vast areas of smaller networks and transmitting huge amounts of data. FDDI sends digital data over fiber-optic cables, which are capable of transmitting enormous data loads at high speed. They are analogous to the spine that serves as the conduit for the human body’s nervous system.