Multiplex communications – Diagnostic testing – Path check
Reexamination Certificate
1998-09-18
2003-06-17
Olms, Douglas (Department: 2661)
Multiplex communications
Diagnostic testing
Path check
C370S388000, C370S241000
Reexamination Certificate
active
06580692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to switching systems. More specifically, the present invention relates to a switching system which provides the ability to interconnect a large number of electronic components in a manner which allows the components to function as if they were physically wired together using virtually any type of data transfer protocol while exhibiting low latency (achieving a total data transfer delay close to the that which would have been achieved in a direct-wired configuration), timing consistency (achieving a latency which is deterministic and predictable), and high signal fidelity (not adding to, deleting from, or altering the signal in any way).
2. Glossary
Before beginning a discussion of either the related art or the preferred embodiments according to the present invention, it should be mentioned that the inventors have opted to employ the following terms throughout the specification. A glossary of these terms are set out immediately below.
Blocking—Blocking refers to a condition wherein a connection is refused even though there are free input and output channels.
Contention—refers to an attempt to connect an input port to an output port which is already in use.
Data Transfer Protocol Insensitive—Data transfer protocol insensitive functional behavior refers to the ability to of the switching system to handle virtually any type of data transfer protocol, i.e., any device can be connected to any other device that uses that same data transfer protocol, without adding to, deleting from, altering, or responding to the transfer protocol in any way. From the discussion immediately above, it will be appreciated that neither the origin nor the destination of any signal is determined by analyzing the associated header or the data content of the signal; switching is completely content-independent or message-independent.
Deliver—Deliver, as used hereinafter, is employed to connote that any specification-compliant signal received is switched and “delivered” as a corresponding specification-compliant output signal. “Delivered” is understood to be broad enough to encompass the general process wherein the input signal, once recognized as a valid signal, is converted into one or more other signal formats as it is handled within the switch, so long as the final output signal “delivered” by the MIPPSS is specification-compliant in its original format.
Distributed System—Distributed system refers to the switching system design wherein each switching unit has the capability of servicing multiple locations, and no single location must house the entire switch. It will be appreciated that this reduces need for costly modifications or additions to facilities to accommodate switching equipment.
Hot-Swapping—Hot-swapping capability refers to the ability to perform on-line replacement of line-replaceable units, i.e., the switching system remains operable overall while discrete, inoperable elements are replaced.
Low Latency—Low latency refers to the ability of the switching system to achieve a total data transfer delay close to the that which would have been achieved in a direct-wired configuration.
Multi-Interface—Multi-Interface functional behavior refers to the ability to handle virtually any type of data transfer protocol, i.e., any device can be connected to any other device that uses that same data transfer protocol.
NTDS—Naval Tactical Data System (NTDS) refers to the Navy's specific implementation of the Military Standard Document entitled “Input/Output Interfaces, Standard Digital Data, Navy Systems,” commonly referred to as MIL-STD-1397 (NAVY). The standard describes interface classifications (Types) and categories of NTDS interfaces, the latter being parallel interfaces, serial interfaces, and other interfaces. For specific information of each NTDS signal type, refer to MIL-STD-1397 (NAVY), the latest version of which, MIL-STD-1397C, is available from the Naval Publications and Forms Center, Philadelphia, Pa., or at http://www.dodssp.daps.mil. MIL-STD-1397 is incorporated herein by reference.
Point-to-Multipoint—Point-to-multipoint functional behavior refers to the ability by which a single data generating device (root node) communicates with a plurality of data receiving devices (leaf nodes). In nodal notation, traffic on the switching system is generated by the root node and received by all of the leaf nodes. Moreover, the switching system does not reserve bandwidth for traffic from any of the leaf nodes toward the root node and the leaf nodes cannot communicate with one another through the point-to-multipoint connection. A switching system capable of point-to-multipoint connections is said to include a broadcast capability.
Point-to-Point—Point-to-point functional behavior generally refers to the ability to connect devices which are required to communicate with one another on a one-to-one basis.
Signal Fidelity—Signal fidelity refers to the ability to replicate the input signal at the output port. High signal fidelity denotes that the signal is delivered without adding to, deleting from, or altering the signal in any way.
Switch Fabric—The components with a switching system that provides paths for the connections. In the discussion which follows, two distinct types of switch fabrics will be considered. The first type is multi-layer switch fabric, where the switch fabric is arranged in layers, i.e., discrete switch enclosures, according to the signal format the individual layers are designed to receive and/or output. The second type is mixed-layer switch fabric, wherein multiple signal formats are received and/or output by a single switch layer, e.g., a single switch enclosure.
Timing Consistency—Timing consistency refers to the ability of the switching system to achieve a latency which is deterministic and predictable. See low latency.
Transparency—Transparent functional behavior refers to the ability to deliver a signal without interaction with the interface protocol corresponding to that signal. Thus, an interface-compliant input signal bit arriving at an input terminal is output as an interface-compliant signal bit, irrespective of whether the bit is a control bit or a data bit. This characteristic is critical when the switch serves to connect objects which are themselves under test, allowing research and testing without introducing additional possible sources of errors due to switching.
3. Brief Discussion of Related Art
The primary utility of MIPPSS is in transparently switching signals between and among components which may not have been originally designed to be switched. The signals can be of virtually any data type (communications, images, sensor data, accounting records) and can be used for any scientific, commercial, or military purpose. See FIG.
1
.
The discussion immediately below provides a review of basic digital communications. In addition, the discussion outlines the need for switching, current methods and apparatus used to perform switching, and the principal limitations and disadvantages of these methods. Several solutions to the overall switching problem solved by MIPPSS are also discussed.
Digital equipment communicates by sending digital signals, which are composed of binary digits, or bits. Each bit represents either a
1
(one) or a
0
(zero).
FIG. 2
shows a representative bit expressed as a deflection from a baseline over a period of time. By convention, most upward deflections are signed positive. The presence of a
1
or a
0
is interpreted according to an agreed-upon encoding technique, as described in greater detail below, but it should be noted here that the presence of a
1
or a
0
may be denoted by positive or negative deflections, positive or negative transitions, or simply by the presence or absence of a transition. Digital signaling is generally superior to analog information transfer because it is capable of very accurate transmission over great distances.
It will be appreciated that the bit is signaled in a digital circuit by varying voltages. The most comm
Brown Gair D.
Calvert, II Gary S.
Cocke, IV Thomas F.
Francis Harry F.
Gorder Timothy Y.
Bechtel, Esq. James B.
Bussan, Esq. Matthew J.
Olms Douglas
Pizarro Ricardo M.
Powell, Jr. , Esq. Raymond H. J.
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