Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Reexamination Certificate
2000-03-13
2004-09-28
Phunkulh, Bob A. (Department: 2661)
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
C370S220000, C370S244000, C714S002000
Reexamination Certificate
active
06798740
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates generally to data transmission in wide area networks, by way of example, the asynchronous transfer mode (ATM) networks. More specifically, the invention relates to error monitoring within the ATM network and to a decision process for switching to the redundant portions of the switching fabric and network.
2. Related Art
Developments with the telecommunication industry has significantly improved the ability for people to communicate, exchange data, perform research, and, more generally, the ability to access information resources that were unavailable even in recent history to the common person. The new communication networks are altering the business landscape and are altering the very way individuals work, shop, and keep in touch with each other. Not only, for example, can one use cellular phone service or e-mail to communicate with others, one can also now obtain large documents, graphic images, databases, and other types of information having significant memory footprints through wireless and wireline networks.
The manner in which the communication networks are evolving creates a need for more capable information access tools (computers and transceivers, for example). The new tools, in turn, create a need for new networks having increase data throughput capacity and reliability. New networks and information exchange capabilities that were unimaginable even in recent times are being developed and implemented in a way that impacts businesses and individuals in a significant way. For example, standalone computers may now be integrated with wireless radio telephones to allow the transmission of information from the computer to a destination by way of a wireless communication network and then by way of the Internet.
The recent explosion of the Internet is creating the capability and desire for networks of all types to be integrated and coupled to exchange data signals carrying the varying types of information. In many cases, the same data also will also be transported through a local area network (LAN) prior to being delivered to the Internet. Thus, by way of example, a digitized signal can be transported from a source through a LAN and through the Internet, to a final destination. Moreover, within the Internet portion itself, there may be a need to transport the user data through a backbone data transport infrastructure, by way of example, through an ATM network.
Generally speaking, the Internet is, in essence, a collection of many large and small computer networks that are coupled together over high speed backbone data links such as T-1, T-3, OC-1 and OC-3. Stated differently, the Internet is a network of networks. As a result of the creation of the Internet, worldwide access may be achieved. People and their equipment may now communicate from most any civilized point to another in a fast and relatively inexpensive medium.
While it is popular to think of the Internet as one network of networks, there are other such Internets that are in existence and that are under development. For example, the network now commonly known as the Internet was originally a network of institutional networks including university networks. As a result of the commercialization of the Internet and the resultant reduction in quality of service, new generation Internet type networks are under development to better achieve the purposes of the original “Internet”. Moreover, new international standards and protocols are being approved to create additional and enhanced Internets. For the sake of simplicity, however, each of the worldwide Internet networks will be referred to collectively as the Internet.
Regarding its physical aspects, the Internet is a packet switched network that is currently based upon a group of protocols known as transmission control protocol/Internet protocol (TCP/IP). TCP is a connection-oriented protocol that first establishes a connection between two computer systems that are to exchange data. TCP then breaks a given digital information signal into packets having a defined format. The packets are then attached to headers that are for containing control and address information.
For example, in addition to a destination address, a TCP packet typically contains a sequence number that is to be used by the destination in reconstructing a signal that is similar to the original digital information that was broken into packets at the originating end. TCP packets also typically include port IDs, checksum values and other types of control information as is known by those skilled in the art.
IP protocol is used for routing purposes. Thus, the IP protocol includes the destination and originating addresses and default gateway identifiers. IP routers, therefore, are operable to evaluate IP protocol information for routing an IP data packet and to evaluate TCP protocol information for error control and other similar purposes.
In order to make communication devices created by companies throughout the world compatible with each other to create local area networks and worldwide networks such as the Internet, protocols and standards are often defined. These protocols and standards are used to guide the design of the communication devices, and more specifically, to guide the design of the operating logic and software within the devices. While communication devices that are designed in view of these standards do not always follow the suggested models exactly, they are usually compatible with the protocol-defined interfaces (physical and logical). In order to appreciate the construction and operation of many devices, it is important to generally understand the concepts of some of the significant protocol standards and models.
One important model that currently guides development efforts is the International Standards Organization (ISO) Open Systems Interconnection (OSI) model. ISO/OSI provides a network framework or model that allows equipment from different vendors to communicate with each other. The OSI model organizes the communication process into seven different categories or layers and places these layers in a sequence based on their relation to the user. Layers 1 through 3 deal provide actual network access and control. Layers 4 through 7 relate to the point to point communications between the message source and destination.
More specifically, the seven layers in the OSI model work together to transfer communication signals through a network. Layer 1 includes the physical layer meaning the actual hardware that transmits currents having a voltage representing a bit of information. Layer 1 also provides for the functional and procedural characteristics of the hardware to activate, maintain, and deactivate physical data links that transparently pass the bit stream for communication between data link entities. Layer 2 is the data link layer or the technology specific transfer layer that effectuates and controls the actual transmissions between network entities. For example, layer 2 provides for activation, maintenance, and deactivation of data link connections, character and frame synchronization, grouping of bits into characters and frames, error control, media access control and flow control.
Layer 3 is the network layer at which routing, switching and delaying decisions are made to create a path through a network. Such decisions are made in view of the network as a whole and of the available communication paths through the network. For example, decisions as to which nodes should be used to create a signal path are decided at layer 3. As may be seen, layers 1, 2 and 3 control the physical aspects of data transmission.
While the first three layers control the physical aspects of data transmission, the remaining layers relate more to communication functionality. To illustrate, layer 4 is the transport layer that defines the rules for information exchange and manages the point to point delivery of information within and between networks including providing error recovery and flow control. Layer 5 is the session layer that controls the
Hunter Van
Reddy Sri
Senevirathne Tissa
Garlick Bruce E.
Harrison James A.
Nortel Networks Limited
Phunkulh Bob A.
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