Network Architectures

Written by Julianus Yu

Network architectures include Ethernet, Token Ring, Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM), and 100VG-AnyLAN, capable of operating on other media as well as predominant cabling infrastructure "UTP".

Ethernet
Ethernet is the most mature and common of the network architectures. According to technology analysts IDC (International Data Corporation), Ethernet is used in over 80 percent of all network installations. Over the past 25 years, despite stiff competition from more modern network architectures, Ethernet has flourished. In the past 10 years alone, Ethernet has been updated to support speeds of 100Mbps and 1000Mbps; currently 10 Gigabit Ethernet is being deployed over optical fiber and research is progressing to make it available over UTP.

Why is Ethernet so popular? Because on a properly designed and cabled network, Ethernet is fast, easy to install, reliable, and inexpensive. Ethernet can be installed on almost any type of structured cabling system, including unshielded twisted-pair and fiber-optic cable. Gigabit Ethernet deployment is still in the early stages, and we don’t expect to see it extended directly to the desktop in most organizations. The cost of Gigabit Ethernet hubs and networkinterface cards is too high to permit this in most environments. Only applications that demand the highest performance will actually see Gigabit Ethernet to the desktop in the next few years.

Token Ring
Token Ring uses a ring architecture to pass data from one computer to another, Token Ring employs a sophisticated scheme to control the flow of data. If no network node needs to transmit data, a small packet, called the free token, continually circles the ring. If a node needs to transmit data, it must have possession of the free token before it can create a new Token Ring data frame. Token Ring operates at either 4Mbps or 16Mbps; however, a ring only operates at a single speed. (That’s unlike Ethernet, where 10Mbps and 100Mbps nodes can coexist on the same network.) Care must be taken on older Token Ring hardware that a network adapter operating at the wrong speed is not inserted into a ring because doing so can shut down the entire network.

Fiber Distributed Data Interface (FDDI)
Fiber Distributed Data Interface (FDDI) is a networking specification that was produced by the ANSI X3T9.5 committee in 1986. It defines a high-speed (100Mbps), token-passing network using fiber-optic cable. In 1994, the specification was updated to include copper cable. FDDI can operate as a true ring topology, or it can be physically wired like a star topology.

Asynchronous Transfer Mode (ATM)
ATM (asynchronous transfer mode, not to be confused with automated teller machines) first emerged in the early 1990s. ATM was designed to be a high-speed communications protocol that does not depend on any specific LAN topology. It uses a high-speed cell-switching technology that can handle data as well as real-time voice and video. ATM is a connection oriented service, in contrast to many network architectures, which are broadcast based.

100VG-AnyLAN
What does the VG stand for? Voice grade. The 100VG-AnyLAN was designed to operate over a minimum of Category 3 cable using all pairs in a four-pair UTP cable. It could also be implemented over fiber-optic and STP cabling. But, because it was rapidly overtaken by inexpensive 100Base-T solutions, it was never implemented widely and is effectively extinct.