Token ring is a local area network protocol which resides at the data link layer (DLL) of the OSI model. It uses a special three-byte frame called a token that travels unidirectionally around a star-wired logical ring. Token ring frames travel completely around the loop. The name 'Token Ring' is misleading since the physical topology is a loop.
Each station passes or repeats the special token frame around the ring to its nearest downstream neighbor. This token-passing process is used to arbitrate access to the shared ring media. Stations that have data frames to transmit must first acquire the token before they can transmit them. Token ring LANs normally use differential Manchester encoding of bits on the LAN media.
Token ring was invented by Olof Söderblom in the late 1960s. It was later licensed to IBM, who popularized the use of token ring LANs in the mid 1980s when it released its IBM token ring architecture based on active multi-station access units (MSAUs or MAUs) and the IBM Structured Cabling System. The Institute of Electrical and Electronics Engineers or IEEE (http://www.ieee.org) later standardized a token ring LAN system as IEEE 802.5 (http://www.ieee802.org/5/).
Token ring LAN speeds of 4Mbps, 16Mbps, 100Mbps and 1Gbps have been standardized by the IEEE 802.5 working group.
Token ring networks had significantly superior performance and reliability compared to early shared-media implementations of Ethernet (IEEE 802.3), and were widely adopted as a higher-performance alternative to shared-media Ethernet.
However, with the development of switched Ethernet, token ring architectures lagged badly behind Ethernet in both performance and reliability. The higher sales of Ethernet allowed economies of scale which drove down prices further, and added a compelling price advantage to its other advantages over token ring.
Token ring networks have since declined in usage and the standards activity has since come to a standstill as switched Ethernet has dominated the LAN/layer 2 networking market.
The Token Frame
When no station is transmitting a data frame, a special token frame circles the loop. This special token frame is repeated from station to station until arriving at a station that needs to transmit data. When a station needs to transmit a data frame, it converts the token frame into a data frame for transmission. The special token frame consists of three bytes as follows:
Starting Delimiter - consists of a special bit pattern denoting the beginning of the frame. The bits from most significant to least significant are J,K,0,J,K,0,0,0. J and K are code violations.
The Unistep IRP Elexol EtherIO 24 Module is a network board that is integrated with features that allow multiple devices over the same network to communicate. This microcontroller was designed to be implemented as an addition to a larger network system; the multiple features and capabilities allow for various industrial and home applications. Ethernet is very common and used in most networks, which makes the IRP a great candidate for networking problems both at home and in the work field.
The Jaagz’ local area network will use category 5 cable and run IEEE 802.3 protocol. Using IEEE 802.3, the network speed will average about 10 Mbps. It will utilize a combination of a star and bus topology, which is the most common topology used in networks. The bus topology makes up the backbone of the network while the star topology branches out.
Meanwhile, the advent of early PC’s and the recognition of the value in networking devices together gave rise to Local Area Networks. These LAN’s were developed from a business customer perspective, which placed more emphasis on costs and ease of use over reliability. There were a number of different competing LAN technologies, two of the most common being Token Ring (IBM) and Ethernet (everyone else). The triumph of Ethernet in the marketplace, to the extent where it is included in every PC, game console and some refrigerators, provides a consistent and relatively inexpensive way to build internal networks with relative ease.
A switch can be used to make various connections. Ethernet, Token Ring, and various other types of packet switched network segments together to form a heterogeneous network operating at OSI Layer 2.
...he secret of its success in the field of computer networking, and this is also the key to its use in other areas of communication as well.
MPLS was originally proposed by a group of engineers from Ipsilon Networks, but their "IP Switching" technology, which was defined only to work over ATM, did not achieve market dominance. Cisco Systems, Inc. introduced a related proposal, not restricted to ATM transmission, called "Tag Switching" when it was a Cisco proprietary proposal, and was renamed "Label Switching" when it was handed over to the IETF for open standardization. The IETF work involved proposals from other vendors, and development of a consensus protocol that combined features from several vendors' work.
When desktop computers and Local Area Networks (LAN) appeared in the 1980’s, they were small scale and being somewhat complex they required hands on technical skills, so were acquired in limited quantities. The low cash costs also meant they were often purchased without the approval of senior management.
In the ring topology, each node is connected to two other nodes, hence, “data sent between nodes will typically require paths of at least two links” (Mansfield, K. C., & Antaonakos, J. L., 2010, p. 27). Among some of the advantages of the ring topology is its organization, the reduction of collision and the one direction traffic flow at very high speed. Another advantage is that for connectivity between workstations, there is no need for network server to control such connectivity and each computer system has the same access to all network resources.
ATM is geared toward high speed voice and video transmission, much like a telephone network. It uses a cell-switching and multiplexing technology. The data (this refers to data, voice and video) is transferred between two points on a dedicated circuit in 53 byte cells. Each cell is the exact same size, no matter what data is being sent. The cells consist of 5 bits of header information and 48 bits of actual data. Using a smaller, consistent cell size means there's less delay between when each cell processes at the other end. Using dedicated circuits via virtual circuits ensures there is no interruption in the data transfer. This is extremely important to voice and video transmissions, because they are highly intolerant to data delays. This improves the Quality of Service (QoS) and speed of transfer, which can be between 25 Mbps to 622 Mbps.
Figure 2.11 above shows the network topology in a single lab. In the lab, a star topology is used to connect a printer, a wireless access point and 50 personal computers with a single special device known as switch. Instead of using hub, a switch is used to identify which computer system is connecting to which port. Switch knows exactly where a frame is received from and which port it wants to send to, without increasing the network response time. Unlike a hub which divides the bandwidth among the systems when multiple PCs are broadcasting, switch enables system users to access the maximum amount of bandwidth regardless the number of PCs transmitting. Thus, a switch is considered as a better choice than a hub because it maintains the performance instead of degrading.
Ethernet originally contested with two mainly branded schemes, Token Ring and Token Bus. Since Ethernet was bright to familiarize to shop realisms and change to cheap and universal twisted pair wiring, these branded protocols later initiated themselves opposing in a advertise flooded by Ethernet goods, and, by the conclusion of the 1980s, Ethernet was obviously the primary network equipment.
In communication networks, research was performed on Fiber Optics Local Area Networks such as Fastnet, Expressnet, D-Net, U-Net and Token Ring as they are key networks for factory automation. This leads to interest in modelling and testing of High Speed Networks, which is paramount for the successful development of multimedia systems.
Local Area Networks also called LANs have been a major player in industrialization of computers. In the past 20 or so years the worlds industry has be invaded with new computer technology. It has made such an impact on the way we do business that it has become essential with an ever-growing need for improvement. LANs give an employer the ability to share information between computers with a simple relatively inexpensive system of network cards and software. It also lets the user or users share hardware such as Printers and scanners. The speed of access between the computers is lighting fast because the data has a short distance to cover. In most cases a LAN only occupies one or a group of buildings located next to each other. For larger area need there are several other types of networks such as the Internet.
Ring- Like the bus, a Token Ring network uses a single cable. Unlike the bus, the cable's ends are looped to form a complete logical circle or ring. Unlike the bus, when a workstation needs to transmit data over the network, it must wait until the token is passed to it by its neighboring station. It takes control of the station and then places a data packet on the network.
...al. According to the textbook, “[today,] Ethernet is the most popular network standard for LANs [local area networks] because it is relatively inexpensive and easy to install and maintain.” The most common Ethernet connection speeds are “Fast Ethernet”, capable of 100 Mbps, “Gigabit Ethernet” which is capable of 1 Gbps, and even “100-Gigabit Ethernet”.