Network termination

Details Network termination Network termination

1998-03-20

2001-11-20

Ton, Dang (Department: 2661)

Multiplex communications

Pathfinding or routing

Switching a message which includes an address header

Reexamination Certificate

active

06320866

ABSTRACT:

TECHNICAL FIELD
This invention relates to a network termination for a digital communications network.
BACKGROUND OF THE INVENTION
Such network terminations are needed at the subscriber interface in various digital communications networks. For example, there are standard network terminations and primary multiplex network terminations for ISDN (2 Mb). Network terminations are also used in ATM (asynchronous transfer mode)-based digital communications networks and in networks based on other transmission techniques.
An article by W. Harderich (“ISDN-Produkte für Europa”, telekom praxis 3/94, pp. 29-35) describes that a network termination for ISDN is made available to a subscriber and installed by a network operator. On the other hand, however, the network termination is on the subscriber's premises and is supplied with power by the subscriber.
A problem associated with this constellation arises if the power supply of the network termination is interrupted by a power failure at the subscriber. The subscriber will notice at a terminal only that a malfunction has occurred in the communications network but cannot locate the error and will not realize that the correction of the error falls within his or her purview.
The same problem is encountered with leased lines by which a customer interconnects different ones of his subnetworks via a public network. Here, too, network terminations of the public network operator are installed on the customer's premises and supplied with power from the customer, and it is not possible for the customer to detect a power failure at the network terminations. For 2-Mb PCM (pulse code modulation) connections, an error indication bit (SA bit) is defined in the frame of the message signals which is set in the event of a power failure at the network terminations in order to signal the error, but this error indication bit can be transmitted only to the public network operator, not to the customer.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a network termination which in the event of a power failure permits error detection by a customer responsible for the supply of power. Another object of the invention is to provide a method of signaling a power failure at a network termination.
These objects are attained by the a network termination for a communications network, the network termination comprising a power supply connectable to an external power source, having means for detecting a power failure of the external power source, means for maintaining power for a predetermined period of time in the event of a power failure, and means for sending an error message in the payload of a message signal.
The objects are also attained by a method of signaling a power failure at a network termination of a communications network, comprising the steps of detecting the power failure at the network terminations; maintaining power for a predetermined period of time; sending an error message in the payload of a message signal; and detecting the error message.
One advantage of the invention is that it makes available a power failure message at a management system of the customer. It is therefore especially suitable for leased lines, over which an error indication bit cannot be transmitted from one end to the other.
The invention can also be used to advantage where the feed-in point of a digital communications network is not in the same room or the same building as the customer's signal-processing circuitry and where a power failure cannot be detected by the fact that other transmission equipment also fails because of the power failure.


REFERENCES:
patent: 4500989 (1985-02-01), Dahod
patent: 4989202 (1991-01-01), Soto et al.
patent: 5175767 (1992-12-01), Landry
patent: 5499048 (1996-03-01), Seo
patent: 5530748 (1996-06-01), Ohmori
patent: 5673252 (1997-09-01), Johnson et al.
patent: 5883944 (1999-03-01), Burke et al.
patent: 29601274 (1997-02-01), None
patent: 0647044 (1995-04-01), None
“Stromversorgung.von Zustzgeräten am ISDN-Hauptanschlu&bgr;” by Dieter Klein, In: ntz, Bd. 41 1988, H-10, S. 566-569.
“ISDN-Produkte für Europa”, telekom praxis 3/94, pp. 29-35, by Wolfgang Harderich, Peine.

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