System and method to provide aggregated alarm indication signals

In an example embodiment, a method and system to provide aggregated alarm indication signals is provided. In example embodiments, an affected intermediate node detects a signal failure. A list of affected networks is determined, and a single aggregated alarm indication signal (AIS) message is generated per MEG level. The aggregated AIS message is then multicast to affected nodes. Instead of sending one AIS message per affected network, a single aggregated AIS message from the affected intermediate node may be generated and sent regardless of the number of affected networks.

FIELD

The present disclosure relates generally to computer networks. In an example embodiment, the disclosure relates to providing aggregated alarm indication signals.

BACKGROUND

An alarm indication signal (AIS) is typically used to indicate a signal failure. The use of the AIS is widely popular and used in many transport platforms and standards, and also used in various applications. For example, the AIS may suppress alarms that are on nodes that are not the root cause of a failure. Further, the AIS may trigger protection switching, for instance, by switching a node to a protected service virtual local area network (SVLAN). In another example, the AIS may raise a non-critical and non-reportable alarm (e.g., not reported to a user autonomously) to a network management system.

DETAILED DESCRIPTION

The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, example embodiments in which the claimed subject matter may be practiced. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of various embodiments of the inventive subject matter. It will be evident, however, to those skilled in the art that embodiments of the inventive subject matter may be practiced without these specific details. In general, well-known instruction instances, protocols, structures, and techniques have not been shown in detail. As used herein, the term “or” may be construed in either an inclusive or exclusive sense.

Overview

Embodiments provide systems and methods to provide an aggregated alarm indication signal. In example embodiments, an intermediate node detects a signal failure. A list of affected nodes is determined, and an aggregated alarm indication signal (AIS) message is generated. The aggregated AIS message is then multicast to the affected nodes. Instead of sending one AIS message per network, a single aggregated AIS message from the affected intermediate node may be generated and sent regardless of the number of affected networks. For simplicity of discussion, references to a node and a switch are used interchangeably below.

Example Embodiments

FIG. 1depicts a diagram of an example conventional alarm indication signal (AIS) example environment. In this example environment, a plurality of nodes (e.g., node A102, node B104, node C106, node D108, node E110, and node F112) are coupled in communication via a plurality of local area networks (e.g., depicted with lines inFIG. 1). The local area networks (LANs) comprise virtual LANs, and more particular, service virtual LANs (SVLANs).

If a link failure114occurs between nodes, such as intermediate node C106and intermediate node D108, a plurality of AIS messages are typically generated. Specifically, the affected node C106generates five AIS messages, one message for each SVLAN associated with node C106(e.g., three AIS messages to node A102and two AIS messages to node B104). Similarly, node D108also generates five AIS messages, one message for each SVLAN associated with node D108(e.g., three AIS messages to node E110and two AIS messages to node F112). Because, for example, the ITU-T Y.1731 standard defines that one AIS message is sent per SVLAN, the example environment ofFIG. 1will result in ten AIS messages being sent (assuming a single maintenance entity group level).

FIG. 1illustrates a simplified example of the conventional AIS environment. Hundreds of SVLANs may be initiated by an edge node or switch (e.g., node A102, node B104, node E110, and node F112). As a result, the affected intermediate node (e.g., node C106or node D108) may create a storm of AIS messages to these edge nodes, especially if the affected intermediate node is close to either a source or destination. In embodiments having large gigabyte interfaces (e.g., 40 gigabit or 100 gigabit interfaces) that carry thousands of services, a single failure in a link may trigger hundreds or thousands of alarms and AIS messages.

Attempts have been made to mitigate this problem. For example, after generating the first few AIS messages on a SVLAN, AIS message generation may be cooled off. That is, instead of generating a message every second, for example, a message may be generated every minute. However, all the messages still need to be generated. Thus, there is no reduction in the number of AIS messages generated by the affected intermediate node. In fact, the cooling off process may cause inefficient protection switching when AIS messaging is used as a trigger. Furthermore, the edge node still needs to process many AIS messages if the edge node has sourced any SVLANs that go through a link subject to the failure.

An aggregated AIS environment ofFIG. 2allows an aggregated AIS message to be generated instead of individual AIS messages for each SVLAN and each node. In this example environment, a plurality of nodes (e.g., node A202, node B204, node C206, node D208, node E210, and node F212) are coupled in communication via a plurality of virtual local area networks (e.g., depicted with lines inFIG. 2). A management service virtual LAN (SVLAN)216also communicatively couples the various nodes ofFIG. 2.

In this embodiment, when a link failure214between nodes, such as intermediate node C206and intermediate node D208, occurs, a single aggregated AIS message is generated by the affected intermediate node where the signal failure occurs (e.g., node C206) for each maintenance entity group (MEG) level. The aggregated AIS message is then multicast towards edge node A202and node B204. In one embodiment, up to eight MEG levels may be present, thus resulting in eight aggregated AIS messages. In example embodiments, the aggregated AIS message is sent via the management VLAN216.

Because of the drastic reduction in AIS messages that need to be generated and transmitted, processing, as an example, may be reduced and bandwidth available for use on the system may be increased. For example, the edge nodes will process fewer AIS messages from the same affected intermediate node. This may result in a quicker response time for the edge node to handle the signal failure.

It should be noted that in the embodiments ofFIG. 1andFIG. 2, any number of other intermediate nodes may be positioned between the depicted intermediate nodes (e.g., node C and node D) and the edge nodes (e.g., node A, node B, node E, and node F). These downstream intermediate nodes of the transport circuit or environment propagate the AIS message onward to the destination or edge node.

FIG. 3depicts an affected intermediate node300of the aggregated AIS environment, according to an example embodiment. The affected intermediate node300detects a signal failure and generates AIS messages accordingly. The affected intermediate node300may be, for example, node C206or node D208ofFIG. 2. The affected intermediate node300comprises a failure detection module302, a list module304, an aggregated messaging module306, and a multicast module308. The affected intermediate node300may comprise other modules or components not directly related to AIS message generation, which are not shown or described.

The failure detection module302detects a signal failure or any other event that can trigger an AIS message that occurs on the affected intermediate node300. In example embodiments, the affected intermediate node300is the node where the signal failure occurs (or is the closest node to the signal failure). Alternatively, the affected intermediate node300may be the closest node to a segment break in the management VLAN.

The list module304compiles a list that is used by the affected intermediate node300to generate the aggregated AIS message. The list may, in one embodiment, comprise all SVLANs that are affected by the signal failure on a link. The list may also include all link failures and hence all SVLANs information on these links on a given port. The list may be based on a configured MEG level.

In example embodiments, the aggregated messaging module306generates a single aggregated AIS message per MEG level. The aggregated AIS message may indicate all ports and all SVLAN information of the affected ports.

The multicast module308multicasts the aggregated AIS message. The aggregated AIS message essentially takes the place of the failed data. In example embodiments, the aggregated message is multicast via the management VLAN. The multicast may be performed using, for example, a multicast address of DA 01-80-C2-00-00-3y, where y represents a MEG level, using an ITU-T Y.1731 standard. However, any standard or multicast address may be utilized in alternative embodiments.

FIG. 4depicts an edge node400of the aggregated AIS environment, according to an example embodiment. The edge node400receives and processes the aggregated AIS message. The edge node400may, for example, be node A202, node B204, node E210, or node F212ofFIG. 2. In example embodiments, the edge node400may comprise a receiver module402, a parse module404, and a processor module406. The edge node400may also comprise other modules or components not directly related to AIS message processing, which are not shown or described herein.

The receiver module402receives the aggregated AIS message sent from the affected intermediate node. Because each MEG level may have a separate aggregated AIS message, the edge node400may receive more than one aggregated AIS message from the affected intermediate node. However, the number of aggregated AIS messages is limited to the maximum number of MEG levels available (e.g., eight).

The parse module404parses the received aggregated AIS message. The parsed AIS message may provide information such as the list of affected SVLANs or any other information related to AIS.

In example embodiments, the processor module406processes the information obtained from parsing the AIS message. Specifically, the processor module406processes an AIS failure against all the SVLANs reported in the aggregated AIS message. This processing of the AIS failure may be similar to conventional processing of an AIS failure (e.g., as if the AIS failure is reported against each SVLAN as conventionally performed).

If the edge node400is serving as both a MEG end point (MEP) and a MEG intermediate point (MIP), then the processor module406may aggregate alarm indication signals. That is, the processor module406will process the edge node's own link faults and aggregate network level alarm indication signals that the edge node400received internally from a domain at the MEP's management level. In some embodiments, the edge node400may include some of the modules for the intermediate node300ofFIG. 3. The aggregated network level alarm indication signals may be forwarded on towards a further edge node for which the edge node400is acting as a MIP.

FIG. 5depicts a flow diagram of a method500to provide aggregated AIS messaging, in accordance with an example embodiment. In operation502, a signal failure is detected. In example embodiments, the failure detection module302(as shown inFIG. 3) of the affected intermediate node where the signal failure occurs detects the failure. For example and referring toFIG. 2, a signal failure may occur at or near intermediate node C206.

A list of affected networks is generated in operation504. The list may comprise virtual local area networks and more particularly, service virtual local area networks (SVLANs) that are affected by the signal failure with a configured MEG level. The list may also include all link failures and hence all SVLANs information on these links on a given port. Continuing with the example environment ofFIG. 2, the list of SVLANs affected by the signal failure at node C206includes SVLANs communicatively coupling node C206with node A202and node B208.

At operation506, an aggregated AIS message is generated for each MEG level. The aggregated AIS message may cover all port and SVLAN information of the affected ports.

The aggregated AIS message is multicast in operation508. In example embodiments, the multicast module308multicasts the aggregated AIS message towards affected edge nodes via a management VLAN. In the example ofFIG. 2, the aggregated AIS message is sent from node C206to node A202and node B204using the management VLAN216.

FIG. 6depicts a flow diagram of a method600to process a received aggregated AIS message, in accordance with an example embodiment. At operation602, the aggregated AIS message is received by a receiver module402(as shown inFIG. 4) of an edge node (e.g., node A202). The aggregated AIS message may, in some embodiments, be forwarded through one or more intermediate nodes before reaching the edge node.

Once received, the aggregated AIS message is parsed in operation604. In example embodiments, the parse module404of the edge node400parses the aggregated AIS message to determine the list of affected SVLANs. Other information associated with the signal failure may also be extracted from the aggregated AIS message.

At operation606, the AIS failure is processed. In one embodiment, the processor module406of the edge node400processes the AIS failure against all the SVLANs reported in the aggregated AIS message. This processing of the AIS failure occurs in a similar manner to conventional processing of an AIS failure.

At operation608, a determination is made as to whether the edge node400is serving as both a MEG end point (MEP) and a MEG intermediate point (MIP). If the edge node400is serving as both a MEP and a MIP, then at operation610, the edge node400processes its own faults and aggregates any network level alarm indication signals.

It should be noted that on an edge switch where MEPs are created, edge switch hardware (e.g., receiver module402) may be programmed such that aggregated AIS messages destined to a management VLAN for a given MEG level may be punted to a control plane (e.g., processor module406).

As such, a signal failure will generally trigger generation of a single aggregated AIS message, per MEG level, by the affected intermediate node, which is experiencing the signal failure. This results in a reduction from the many messages (as many as there are SVLANs passing through a link of the affected intermediate node) that are required by conventional systems. Consequentially, in one embodiment, a single aggregated AIS message, per MEG level, needs to be processed by the edge node (as opposed to as many messages as there are SVLANs sources/destined on the edge node). Thus, if there is only one domain and no segmentation in the management VLAN, then one aggregated AIS message is generated.

Furthermore, because the aggregated AIS message is multicast in the management VLAN, one aggregated message per node or switch, per MEG level, is good for the entire network. Thus, only one aggregated message per node or switch may need to be processed, per MEG level. If there is a segmentation in the management VLAN, then one AIS message is generated for each MEG level on either side of the segment caused by the signal failure. Therefore, in a single domain embodiment, as few as two aggregated AIS messages are generated.

The generation and processing times can be dramatically reduced over conventional systems. For example, the AIS message can be generated in a millisecond order resulting in processing of the AIS message in an order of milliseconds. This may result in faster protection switch overs (e.g., in terms of sub-50 millisecond path protection switch over using a G.8031 APS mechanism). Additionally, up-to-date (e.g., quicker) error reporting to the network management system may occur since there is no cool off after the first AIS message generation.

Modules, Components, and Logic

Additionally, certain embodiments described herein may be implemented as logic or a number of modules, engines, components, or mechanisms. A module, engine, logic, component, or mechanism (collectively referred to as a “module”) may be a tangible unit capable of performing certain operations and configured or arranged in a certain manner. In certain example embodiments, one or more computer systems (e.g., a standalone, client, or server computer system) or one or more components of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or application portion) or firmware (note that software and firmware can generally be used interchangeably herein as is known by a skilled artisan) as a module that operates to perform certain operations described herein.

In various embodiments, a module may be implemented mechanically or electronically. For example, a module may comprise dedicated circuitry or logic that is permanently configured (e.g., within a special-purpose processor, application specific integrated circuit (ASIC), or array) to perform certain operations. A module may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software or firmware to perform certain operations. It will be appreciated that a decision to implement a module mechanically, in the dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by, for example, cost, time, energy-usage, and package size considerations.

Example Machine Architecture and Machine-Readable Medium

The example computer system700may include a processor702(e.g., a central processing unit (CPU), a graphics processing unit (GPU) or both), a main memory704and a static memory706, which communicate with each other via a bus708. The computer system700may further include a video display unit710(e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). In example embodiments, the computer system700also includes one or more of an alpha-numeric input device712(e.g., a keyboard), a user interface (UI) navigation device or cursor control device714(e.g., a mouse), a disk drive unit716, a signal generation device718(e.g., a speaker), and a network interface device720.

The disk drive unit716includes a machine-readable medium722on which is stored one or more sets of instructions724and data structures (e.g., software instructions) embodying or used by any one or more of the methodologies or functions described herein. The instructions724may also reside, completely or at least partially, within the main memory704or within the processor702during execution thereof by the computer system700, the main memory704and the processor702also constituting machine-readable media.

Transmission Medium