Multiplex communications – Fault recovery – Bypass an inoperative channel
Reexamination Certificate
1999-09-01
2004-08-31
Qureshi, Afsar (Department: 2667)
Multiplex communications
Fault recovery
Bypass an inoperative channel
C370S221000, C370S225000, C370S421000, C709S239000
Reexamination Certificate
active
06785226
ABSTRACT:
TECHNICAL FIELD
The invention pertains to communication networks in general and in particular to system and method for providing fault tolerance in an Ethernet based network communication system.
BACKGROUND
Communications networks typically include multiple nodes which communicate with each other over communications links. It is useful to think of the nodes as separate from the communications links, since they are often provided, maintained, and operated by different organizations and generally include and/or are coupled to termination devices actually utilizing the data or information communicated through the network. Each node in a network may include or be coupled to one or more computers or other information processing system, such as a telephony device, generically referred to herein as the “node computer”, for performing a variety of tasks. Each node can communicate directly with one or more other nodes through communications links, which might be implemented with wires, optical fiber, radio transmissions, and/or some combination of these. Each link is often terminated at each end with an interface device, such as a modem or network interface card (NIC), which converts the signals from the associated node computer into and from a format suitable for the particular type of link. The information to be communicated between nodes can be generically referred to as “user data”, and it allows the various nodes to perform their functions in a distributed manner. The standard industry term “user data” is a carryover from the early days of computers, and does not imply that a human user must be involved. The content of user data is typically independent of the type of communications links being used.
It is desirable for any node in a network to be able to communicate a user message (i.e., a quantity of user data) to any other node. The most direct way of accomplishing this is to provide a separate link from every node to every other node, and let the transmitting node select the proper link for a given message. However, if the network has very many nodes, the number of links required would be prohibitively expensive. To avoid this problem, many networks allow a message to be passed from node to node, or via some other form of shared use link, until the message reaches its final destination. This greatly reduces the number of links needed to send a message from any node to any other node. In “ring” networks (the nodes are connected in a loop), each node will typically have only two links, connecting it to two other nodes, and every message is simply passed around the loop until it reaches its destination node.
In a typical network, every user node is assigned a network “address” and every message contains the address of its destination node. Nodes have the capability to examine the address of a received message, keep and process the message if it sees its own address, or forward the message to another node if it does not see its own address.
While most conventional network links are “hard” links (copper wire or fiber-optic), network communications over radio links have also been developed. Large scale microwave networks may be deployed using millimeter wave technology, such as shown in the above referenced patent application entitled “COMMERCIAL NETWORK BASED ON POINT TO POINT RADIOS” involving the deployment of hundreds of links in a service area. Each of these links may carry customer traffic for the services provided by a telecom operator or other service provider, i.e., the traffic can be Internet e-mails, phone calls, video conference calls, etc. and/or these links may carry customer traffic for the services of another type of service provider, such as a computer network service provider, or even a private system's traffic.
One protocol for providing communication among nodes in a network is the Ethernet networking system. Ethernet protocol defines a shared bus topology in which all nodes on a network generally have access to all data placed on the network. While Ethernet is a common and convenient networking system, it lacks an effective mechanism for link fault tolerance. Therefore, the existence of a faulty connection could disrupt communication on a network without there being a built in remedy to address the disruption.
Where the network is entirely contained within a secure environment, a shared bus topology may not be problematic. However, where it is desired to protect the security and privacy of data associated with each node on a network from access by any other node on the network, standard Ethernet operation could present the problem of network users having access to data which is not intended or authorized.
Therefore, there is a need in the art for establishing link fault tolerance in an Ethernet or other shared link based networking system.
There is a further need in the art for a mechanism to provide security and privacy for data associated with a particular node in an Ethernet environment.
SUMMARY OF THE INVENTION
These and other objects, features and technical advantages are achieved by a system and method which conducts communication between a plurality of nodes in a network employing Ethernet or other form of Open Systems Interconnection (O.S.I.) layer two switching in a point to point transmission scheme. Routers or other form of layer three network data routing device may be advantageously incorporated at selected points in the network to provide redundant communication paths and thereby enable fault tolerance and prevent infinite looping of messages through the network. This network configuration may be referred to as consecutive point transmission. In this application, when no specific O.S.I. level is identified in connection with the term “switch”, the term “switch” refers to a layer two switch.
In a preferred embodiment, the network comprises nodes which are serially connected to form a complete ring wherein each node in the ring communicates with immediately neighboring nodes in both directions around the ring. This configuration preferably comprises routers at opposed ends of the ring network to control the transmission of messages within the network. This configuration provides fault tolerance by presenting alternative paths around the ring for any particular transmission.
In a preferred embodiment, communication between nodes in the communication network is achieved via wireless radio links preferably in the millimeter wave band to provide bi-directional communication between serially linked nodes. Alternatively, wired connections incorporating copper wire or fiber optic cable may be employed to provide for bi-directional communication between network nodes. In this application, the term “serially linked” does not refer to a communication format or protocol, but rather to a physical connection configuration of a sequence of network nodes. This may alternatively be described as a chain or daisy chain of nodes in direct sequence. A ring network is one particular network configuration of such a set serially linked nodes.
In a preferred embodiment, a number of O.S.I. layer two protocols may be employed for communication between nodes within a network, whether in a ring or other configuration. Such protocols include but are not limited to: Ethernet and token ring. Preferably, the layer two protocols appropriately cooperate with protocols in different layers within the open systems interconnection model.
A preferred embodiment ring configuration of a consecutive point transmission system employing radio Ethernet communication presents the advantage of inherently providing for redundant paths between any two nodes in the network. This feature would be absent in a straight line point to point transmission system. In a straight line configuration, a fault in a link between nodes would leave parts of the network isolated from each other barring the introduction of an extrinsic link to compensate for the malfunctioning link. (Generally, the deployment of Ethernet, or other O.S.I. layer two protocol, in a ring configuration under normal circumstances, pr
Harris Jim
Oltman David Kelly
Carriercomm, Inc.
Fulbright & Jaworski L.L.P.
Qureshi Afsar
LandOfFree
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