Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-04-21
2002-09-03
Jung, Min (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S410000
Reexamination Certificate
active
06445711
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of sending control communications to devices within a network. More particularly, the present invention relates to the field of sending control communications to bridges within a network for effecting control and allocating resources along a communications route.
BACKGROUND OF THE INVENTION
The IEEE Std 1394-1995 standard, “1394 Standard For A High Performance Serial Bus,” is an international standard for implementing an inexpensive high-speed serial bus architecture which supports both asynchronous and isochronous format data transfers. In addition, the IEEE Std 1394-1995 bus has a universal clock called the cycle timer. This clock is synchronized on all nodes. Isochronous data transfers are real-time transfers which take place based on the universal clock such that the time intervals between significant instances have the same duration at both the transmitting and receiving applications. Each packet of data transferred isochronously is transferred in its own time period. An example of an ideal application for the transfer of data isochronously would be from a video recorder to a television set. The video recorder records images and sounds and saves the data in discrete chunks or packets. The video recorder then transfers each packet, representing the image and sound recorded over a limited time period, during that time period, for display by the television set. The IEEE Std 1394-1995 standard bus architecture provides multiple independent channels for isochronous data transfer between applications. A six bit channel number is broadcast with the data to ensure reception by the appropriate application. This allows multiple applications to simultaneously transmit isochronous data across the bus structure.
Asynchronous transfers are traditional reliable data transfer operations which take place as soon as arbitration is won and transfer a maximum amount of data from a source to a destination. Asynchronous transfers are used for control purposes, including the setup of isochronous communications.
The IEEE Std 1394-1995 standard provides a high-speed serial bus for interconnecting digital devices thereby providing a universal I/O connection. The IEEE Std 1394-1995 standard defines a digital interface for the application thereby eliminating the need for an application to convert digital data to analog data before it is transmitted across the bus. Correspondingly, a receiving application will receive digital data from the bus, not analog data, and will therefore not be required to convert analog data to digital data. The cable required by the IEEE Std 1394-1995 standard is very thin in size compared to other bulkier cables used to connect such devices in other connection schemes. Devices can be added and removed from an IEEE Std 1394-1995 bus while the bus is operational. If a device is so added or removed the bus will then automatically reconfigure itself for transmitting data between the then existing nodes. A node is considered a logical entity with a unique address on the bus structure. Each node provides in a standard address space, an identification ROM, a standardized set of control registers and in addition, its own address space.
The IEEE Std 1394-1995 standard defines a protocol as illustrated in FIG.
1
. This protocol includes a serial bus management block
10
coupled to a transaction layer
12
, a link layer
14
and a physical layer
16
. The physical layer
16
provides the electrical and mechanical connection between a device or application and the IEEE Std 1394-1995 cable. The physical layer
16
also provides arbitration to ensure that all devices coupled to the IEEE Std 1394-1995 bus have access to the bus as well as actual data transmission and reception. The link layer
14
provides data packet delivery service for both asynchronous and isochronous data packet transport. This supports both asynchronous data transport, using an acknowledgement protocol, and isochronous data transport, providing real-time guaranteed bandwidth protocol for just-in-time data delivery. The transaction layer
12
supports the commands necessary to complete asynchronous data transfers, including read, write and lock. The serial bus management block
10
contains an isochronous resource manager for managing isochronous data transfers. The serial bus management block
10
also provides overall configuration control of the serial bus in the form of optimizing arbitration timing, guarantee of adequate electrical power for all devices on the bus, assignment of the cycle master, assignment of isochronous channel and bandwidth resources and basic notification of errors.
IEC-61883 is a ratified international standard for the transport of audio/video command requests and responses. This standard uses the concept of plugs and plug control registers to manage and control the attributes of isochronous data flows. It should be noted that plugs do not physically exist on an audio/video device, but a plug is used to establish an analogy with existing audio/video devices where each flow of information is routed through a physical plug.
An isochronous data flow flows from one transmitting device to one or more receiving devices, by transmitting isochronous packets on an isochronous channel of the IEEE Std 1394-1995 serial bus. Each isochronous data flow is transmitted to an isochronous channel through one output plug on the transmitting device and is received from that isochronous channel through one input plug on the receiving device.
The transmission of an isochronous data flow through an output plug is controlled by an output plug control register (oPCR) and an output master plug register (oMPR) located on the transmitting device. The output master plug register controls all attributes that are common to all isochronous data flows transmitted by the corresponding transmitting device. The output plug control register controls all attributes of the corresponding isochronous data flow that are independent from attributes of other isochronous data flows transmitted by the transmitting device.
The reception of an isochronous data flow through an input plug is controlled by an input plug control register (iPCR) and an input master plug register (iMPR) located on the receiving device. The input master plug register controls all attributes that are common to all isochronous data flows received by the receiving device. The input plug control register controls all attributes of the corresponding isochronous data flow that are independent from attributes of other isochronous data flows received by the receiving device.
An isochronous data flow can be controlled by any device connected to the IEEE Std 1394-1995 bus by modifying the corresponding plug control registers. Plug control registers can be modified through asynchronous transactions on the IEEE Std 1394-1995 bus or by internal modifications if the plug control registers are located on the controlling device.
To transport isochronous data between two audio/video devices on the IEEE Std 1394-1995 bus, it is necessary for an application to connect an output plug on the transmitting device to an input plug on the receiving device using an isochronous channel. The relationship between one input plug, one output plug and one isochronous channel is called a point-to-point connection. A point-to-point connection can only be broken by the application or initiating device that established it. An application can also just start the transmission or reception of an isochronous data flow on its own device by connecting one of its output or input plugs respectively to an isochronous channel. The relationship between one output plug and one isochronous channel is called a broadcast-out connection. The relationship between one input plug and one isochronous channel is called a broadcast-in connection. Broadcast-out and broadcast-in connections are collectively called broadcast connections. A broadcast connection can be established only by the device on which the plug is located, but it can be broken by
James David V.
Scheel Richard K.
Haverstock & Owens LLP
Jung Min
Sony Corporation
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