CZ36405U1 - Passive optical network with anomaly detection - Google Patents

Description

In the registration procedure, the Industrial Property Office does not determine whether the subject of the utility model meets the conditions of eligibility for protection according to § 1 of Act. E. 478/1992 Coll.

CZ 36405 UI

Passive optical network with anomaly detection

Field of technology

The technical solution relates to a passive optical network with anomaly detection consisting of an OLT optical line termination control unit from which a single mode optical fiber exits to a splitter dividing the optical flow to individual end devices of the ONU optical network unit.

Current state of the art

Various types of anomalies occur with existing passive optical networks. Anomaly can represent a denial of services to end customers or a complete disruption of the integrity of the network in terms of functionality and security. An example of an anomaly can be a rogue ONU, which can be classified as a type of attack, or as a modified end unit that does not respect time slots and generates signals in a non-standard format to the optical fiber, usually in continuous mode - it shines continuously, at a wavelength close to the wavelength of the upstream direction , thereby attacking the connected branch to the controller. A similar attack can be implemented by connecting a laser and shining it into the route on a free port of the splitter.

This anomaly manifests itself in the outage of the entire segment, at the output, of the so-called xPON port, of the control unit module of the passive optical network, and thus also in the subsequent unavailability of services for other connected participants in the network, on the same xPON port.

Current solutions do not allow directly detecting or differentiating the nature of the attack.

Individual xPON ports are separated from each other and an attack on one port does not mean an outage on other xPON ports, while there can be up to 16 xPON ports on the module, within the chassis.

Although the controller is equipped with a rouge ONU detection mechanism, the option to find/detect this rouge ONU is not available, the mechanism relies only on a very basic detection of which xPON port the rouge ONU is connected to. The situation will manifest itself basically in the same way as the number of increasing calls to the customer line, because all customers will be affected by the service outage.

The end units will detect this condition by means of a flashing red "PON" LED indicating the unavailability of the optical network.

The aim of this technical solution is to improve the detection of anomalous events arising in passive optical networks, primarily the detection of communication on other wavelengths, the detection of ONU unit errors in terms of protocol/time slots and the detection of a continuous beam in the fiber.

The essence of the technical solution

The essence of a passive optical network with anomaly detection consisting of a control unit (OUT), from which a single-mode optical fiber exits to a splitter that distributes the optical flow to individual ONU terminal devices, is that a detection unit is connected between the OUT control unit and the splitter via an optical coupler, which consists of a patch cord connecting an optical coupler with an analog photoelectric element and a digital domain connected to an evaluation unit. The evaluation unit is connected to the part of the communication interface.

The advantage of this technical solution is the ability to fully monitor the segment/port of the transmission route in real time. The detection unit is able to detect both ONUs not respecting time slots

- 1 CZ 36405 UI (rouge ONU), thus evaluating anomalies, i.e. broadcasting outside the time slot, broadcasting on a different wavelength - outside the recommended wavelength standard of the given terminal unit, which can lead to outage/unavailability of services to customers.

Clarification of drawings

The attached Fig. 1 schematically shows a passive optical network with an inserted detection unit, and Fig. 2 shows the detection unit itself.

An example of the implementation of a technical solution

Fig. 1 shows the connection of the detection unit 8 for detecting and evaluating anomalies in passive optical networks. The detection unit 8 is bidirectional, it operates both in the upstream and downstream directions, and serves primarily to capture the optical flow from the upstream direction, i.e. from the client 7 to the global Internet 1 via the end unit ONU 4, optical fiber 5, optical splitter 6 ( optical power splitter into multiple ports), optical coupler 9, optical fiber 5, OLT control unit 3, router - border router 2 of the service provider to the Internet 1 and further to capture the synchronization from the downward direction, from the Internet 1 to the client 7. Connection detection j unit 8 to the optical distribution network is carried out using an optical coupler 9 for dividing both optical flows.

By connecting the optical coupler 9, the activation process of the ONU 4 terminal units connected to the OUT 3 control unit will be started. The evaluation will be limited only to optical flows in the upward direction from the ONU 4 terminal units to the OUT 3 control unit.

Fig. 2 schematically shows the detection unit 8 connected to the optical coupler 9 between the control unit OUT 3 and the available splitter 6 serving as a hub located in the network of the service provider.

At the input of the detection unit 8, a connecting cable patch cord 22 is arranged with suitable connectors for connecting the detection unit 8 to the optical distribution network in full operation with customers who have an active service and actually transmit data. Subsequently, the optical signal data is converted into electrical signal data in the digital domain 24 of the detection unit 8 using the analog photoelectric element 23.

Subsequently, the data from the electrical domain 24 are transferred to the evaluation part 25, where the protocol part of the downlink direction is evaluated, where the protocol part in the data packet contains fields with specified time slots and unique identifiers - for example, with the ONU-ID and the uplink direction for intensity evaluation optical flow from the upward direction. As part of the intensity evaluation, the instantaneous value of the optical flow from the upward direction is evaluated. The evaluation unit 25 is connected to the part 26 of the communication interface.

If an unwanted - modified ONU 4 end unit is connected to an optical distribution network that does not respect the assigned time slots, transmits on a different wavelength or transmits continuously, changes in the intensity of the optical flow in the upward direction will occur. This will cause an outage in the protocol / digital part of the detection unit 8 and a loss of frame synchronization in the evaluation part. The analog evaluation part records minimal fluctuations in the optical flow corresponding to the intensity of the interfering optical signal.

The evaluation part 25 in cooperation with the electrical domain 24 transmits information about the anomaly to the communication interface 26 for displaying information about the state of the passive optical network to the user or to a superior (supervision) system.

-2CZ 36405 UI

Industrial applicability

The proposed technical solution can be used for evaluation tests of data service providers, verification of 5 offered components and fulfillment of declared parameters according to the recommendations of individual standards of passive optical networks and monitoring of the access part of the passive optical network.

Furthermore, monitoring of unexpected wavelengths (states/anomaly) in the ascending direction until after the evaluation of advanced parameters of individual frames (superframe counter, ONU-ID, detailed 10 analysis of the activation process of terminal ONU units, monitoring of compliance with time slots or rouge ONU monitoring).

Claims (3)

PROTECTION CLAIMS 1. A passive optical network with anomaly detection consisting of an optical line termination (OLT) control unit (3) from which a single-mode optical fiber (5) exits to a splitter (6) dividing 5 the optical flow to the individual end devices of the ONU optical network unit (4 ), characterized by the fact that a detection unit (8) is connected between the OLT control unit (3) and the splitter (6) via an optical coupler (9). 2. Passive optical network with anomaly detection according to claim 1, characterized in that the detection unit (8) consists of a patch cord (22) connecting an optical coupler (9) with an analog photoelectric element io (23) and further of a digital domain (24) connected to the evaluation unit (25). 3. Anomaly detection unit in passive optical networks according to claim 2, characterized in that the evaluation unit (25) is connected to the part (26) of the communication interface.