Multiplex communications – Fault recovery – Bypass an inoperative switch or inoperative element of a...
Reexamination Certificate
1998-04-30
2001-11-27
Kizou, Hassan (Department: 2662)
Multiplex communications
Fault recovery
Bypass an inoperative switch or inoperative element of a...
C370S225000, C370S228000, C370S401000, C709S239000, C709S249000
Reexamination Certificate
active
06324161
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present embodiments relate to digital networks, and are more particularly directed to a multiple network configuration implementing redundancy both within each local network of the configuration as well as between the different remote networks of the configuration, where the redundancy is achieved using a redirect operation across dual media.
Data communication is a critical and everyday part of modern computing, and occurs through the use of various types of networks. Such data communication may be used for various reasons, such as business, science, telecommunications, personal, or entertainment. The span of such data communications may occur in different magnitudes. Particularly, in the network vernacular there has evolved notions of both local area networks (LANs) and wide area networks (WANs). As a generally stated distinction between the definition of a LAN and a WAN, a LAN is for more local communication of data such as within a small location, building, or complex, while a WAN is for communication of data across a greater distance which may be across a nation or even worldwide. Moreover, often a LAN is formed from only one or more locally connected networks, that is, in a manner where a given LAN host station on the network is only capable of communicating to those media which share the same “network” address which corresponds to the host address(es) of the given LAN host station, as is discussed in greater detail below. In contrast, a WAN often includes multiple networks where a given WAN host station may not only communicate to local hosts, but may further communicate via one or more routers with a remote network (and its host stations) where the remote network has a network address different than the network address corresponding to the host address(es) of the given WAN host station. In any event, the existence of networks for purposes of data communication is now very popular, and appears to be a way of life for the foreseeable future.
Various considerations of reliability arise along with the acceptance and proliferation of data communication among networks, one of which is the minimization of down time of a network. In other words, it is known in many types of data communication contexts that it is preferable to reduce or eliminate instances where one or more nodes attached to a network are unable to communicate with one or more of the other nodes also attached to the same network. In this regard, one attempt to minimize downtime of locally connected networks is through the use of so-called redundant solutions. Redundancy typically indicates that some type of resource associated with the network(s) is duplicated, and for reference and possible other purposes a first of these resources may be referred to as a primary resource while the second of these resources is referred to as a secondary resource. In the redundant system, if the primary resource becomes inoperative then the secondary resource is preferably quickly used in place of the primary resource, thereby minimizing or eliminating the chance to perceive the failure of the primary resource. Note that the actual resource or resources which are duplicated in this manner may depend on the particular context and, thus, could include repeating nodes, databases, network media, and still others as will be known by one skilled in the relevant art.
By way of further background, one type of prior art redundancy which has been used in the telecommunications industry has been in the context of an Ethernet LAN, and further involves the implementation of a fairly common network protocol known in the art as IP (internetwork protocol). Often the IP is mentioned as part of TCP/IP or UDP/IP. However, either of those two instances are actually a combination of two standards used in the protocol. For example, with respect to TCP/IP, the first protocol is TCP which is an abbreviation for transport control protocol. The second protocol is the IP introduced above. Although the name TCP/IP combines these two standards, in actuality the standards are implemented in an ordered level manner such that the TCP protocol is closer to the application level and the IP protocol is closer to the physical network connection level. In any event, TCP/IP and UDP/IP are well known and permit packets of information to be sent and received along different types of networks. Returning then to a discussion of the prior art IP approach, which is also detailed in greater fashion later, note that it provides two Ethernet interfaces for each node in the LAN thereby connecting each such node to redundant Ethernet cables. Consequently, assuming no failure of any node in the LAN, then each node may communicate to any other node on the LAN along either (or both) of the two Ethernet cables. However, if a failure occurs along one of the two routes of communication (e.g., a failure in an Ethernet cable), then a node may still communicate to other nodes along the other of the two Ethernet routes of communication. In various contexts such an approach has satisfactorily reduced the amount of network down time and provided valuable reliability to the users of the network.
While the prior art approach of the preceding paragraph provides various benefits, the present embodiments address various of its attributes which in some contexts may provide limitations. As a key example, the above-described approach is constrained to implementation for each single autonomous network, where typically that network is locally formed as a LAN. However, if a first such LAN is connected to one or more remote LANs to form a multiple network WAN, then the prior art approach does not comprehend, for a node in the first LAN, a fault in one of the redundant media in the remote LAN. Further, the prior art approach makes no provision for redundancy along the communication path between the two LANs. Clearly, the use of a WAN which includes multiple networks may be highly desirable or even necessary for various types of communications, with telecommunications as a key example. Thus, an approach which provides redundancy only within each autonomous network LAN may provide unacceptable or at least a severely restrictive limitation in some contexts.
To better understand some of the limitations of the above-described approach to an autonomous network using the IP standard, a brief discussion of IP address formats is now provided. More specifically, under the standards for IP, an IP address for a node on a network is formed by combining four integers typically represented in the following fashion:
Q.R.S.T
Ultimately at the machine level, each of the integers are represented in eight bit binary fashion and thus, provide four “bytes” which are also sometimes referred to as “octets.” Thus, the IP address is a total of 32 bits (i.e., four bytes * 8 bits per byte). As binary values, therefore, the values of Q through T are each between 0 and 255. Thus, in decimal form, the same address may be represented as follows, with numeric ranges substituted for the above:
0-255.0-255.0-255.0-255
Still further principles also apply to these addresses, such as the use of “class” identifiers for class A through class E networks based on the different permitted values of the various bytes of the address. For purposes of this document, a detailed explanation of such additional principles is not presented but instead deference is given to one skilled in the art.
In order to ensure an understanding of the above convention, the limitations of the prior art, and the inventive embodiments described later, note that all IP addresses are divisible into two portions, those being a host (or sometimes called a “node”) address and a network address. The host address is some number of the least significant bits (“LSBs”) of the address (i.e., those to the right of the value), while the network address is then the remaining most significant bits (“MSBs”) of the address. For purposes of this document, therefore, and as i
Alcatel USA Sourcing L.P.
Anderson, Levine & Lintel LLP
Kizou Hassan
Tsegaye Saba
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