Multiplex communications – Diagnostic testing
Reexamination Certificate
1998-07-30
2001-07-10
Hsu, Alpus H. (Department: 2661)
Multiplex communications
Diagnostic testing
C370S389000
Reexamination Certificate
active
06259674
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to a device and method for automatic selective initialization of multi-mode signal controllers located at nodes of a communication system having different interface requirements and, more specifically, to a device and method for automatic selective initialization of a multi-mode signal controller connected to either a private branch exchange (PBX) shelf extension control or a PBX main switch control.
DESCRIPTION OF THE RELATED ART
A PBX serves as a miniature central office for a customer that requires sophisticated local telephony capabilities. For instance, a large business having a campus that includes multiple departments and numerous employees is likely to find it economical to install a PBX to provide intra-campus telephone service and external connections to a public switch telephone network (PSTN) central office. Station lines which connect the PBX switch to the phones of the employees are privately leased or owned and all internal calls are routed through the PBX switch.
In a typical installation of a PBX system, a cabinet houses a host of switching electronics, power supplies, and other computing components. For example, the switching electronics are organized within the cabinet into a number of shelves typically occupying the top portion of the cabinet. Below the switching electronics are the power supply components followed by computer components, including a common control which provides switching functions and system administration for the entire PBX system. A backplane interconnects the various parts of the system, providing data and access control between the switching electronics and the computer.
At times, it is desirable to separate one of the shelves containing switching electronics from the PBX main switch. If a PBX provides telephony for a business which expands to an adjacent building, it might be more cost effective to locate a peripheral shelf at the new building, rather than to equip the new building with an independent PBX system. The peripheral shelf and the main switch can be connected by a fiber optic cable. A first signal controller and a common control are on the main switch side of the fiber optic link, while a second signal controller and a peripheral shelf control are on the peripheral shelf side. The signal controllers perform conversions at the opposite ends of the fiber optic link in order to facilitate communication between the peripheral shelf and the main switch. For instance, the two controllers might communicate information over the fiber optic link in the form of Ethernet packets. The second signal controller at the peripheral shelf side of the link converts signals received from the peripheral shelf control into Ethernet packets to be transmitted to the first signal controller on the main switch side of the fiber optic link. The second signal controller also converts Ethernet packets received from the main switch side signal controller to a format compatible with the peripheral shelf control. The main switch side signal controller performs the opposite format conversions for the common control.
While the two signal controllers perform fundamentally the same functions, the controller operations are mirror images of each other when viewed from the fiber optic link. Each signal controller can be specifically designed to execute its packetizing and depacketizing operations, so that there are two different single-mode controllers that provide the necessary compatibility when connected at the correct ends of the fiber optic link. This requires some duplication of labor in the product design and product manufacture stages of the controllers, but works well for its intended purposes.
Alternatively, a multi-mode signal controller can be designed to allow the controller to be used on either side of the fiber optic link. If the controller is set in one mode, the controller functions as the main switch-side controller described above. On the other hand, the controller can be set in an opposite mode that enables performance of the functions of the peripheral shelf-side controller. Multi-mode signal controllers have the potential of providing significant cost savings.
Care must be taken to ensure that each multi-mode signal controller is properly initialized, based on the side of the fiber optic link on which it is located. Compatibility of switch-side and shelf-side operations is facilitated by providing a universal clock signal. Typically, the clock signal is generated by the common control and transmitted to the peripheral shelf via the fiber optic link. However, if the switch-side controller is improperly set in the second mode during initialization of the controller (i.e., power-up), the controller will be set to receive the clock signal in the fiber optic link, rather than being set to drive the dock signal over the link. At the least, this is likely to render the peripheral shelf inoperable. Moreover, signal conflicts may occur on some channels, as the first and second controllers are both initialized to drive signals over a particular channel. This may cause a system failure.
One method of initializing the multi-mode controllers is to require manual configuration of the settings of the modes. This method requires the presence of a properly trained technician each time that one of the controllers is initialized. Otherwise, the process will be susceptible to error. As a result, the manual setting process may require a significant downtime period each time that initialization is required.
What is needed is a multi-mode signal controller capable of automatic initialization based on the location of the signal controller along a communication path, thereby providing automatic mode selection.
SUMMARY OF THE INVENTION
A method of automatically selecting a mode of operation during an initialization sequence of a multi-mode signal controller includes selectively enabling signal reception and disabling signal driving capabilities of the controller and further includes monitoring the remaining signal traffic to identify the position of the signal controller along a communication path. The identification of the position of the controller along the path is used to determine the desired mode of operation for the controller.
Signal reception at the initializing signal controller is monitored to identify whether the controller is receiving a known pattern of system control (e.g., a clock signal) or is receiving a signal that is indicative of a transmission from a second signal controller (e.g., packetized call information). For example, if the method is executed to first monitor traffic for a signal that is indicative of reception from the second signal controller, detection of the signal identifies the second controller as being operative and being on an end of a communication link opposite to the signal controller undergoing initialization. When this signal is detected, the signal controller undergoing initialization is configured to operate only within a first mode of operation. On the other hand, if the signal is undetected, the method moves to a step of monitoring for a known pattern of system control. For example, the known pattern may be a universal clock signal that synchronizes all the controllers along the communication path. When the known pattern is detected as being received from a source other than the second signal controller, the signal controller undergoing initialization is configured to operate only within a second mode of operation that is compatible with controller performance on a side of a communications link that is common with the source of the known pattern of system control.
In the preferred embodiment, one signal controller is on the same side of the communication link as a control device for generating the known pattern of system control, while the other signal controller is on the same side of the communication link as a controlled device. In the most preferred embodiment, the signal controllers are components of a telecommunications system, such as a PBX, and are st
Hsu Alpus H.
Nguyen Brian
Siemens Information and Communication Networks Inc.
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