Abstract: Communication network routing apparatus and techniques using logical communication links are disclosed. A routing apparatus identifies a logical communication link that it is capable of being used to establish a virtual connection with another routing apparatus within a virtual connection operational domain, which includes multiple sub-domains, of an underlying communication system. A destination that is associated with the routing apparatus and is reachable through the virtual connection is also identified. Information that is indicative of the identified logical communication link and of the identified destination is provided for distribution from a sub-domain of the routing apparatus in the virtual connection operational domain to another sub-domain within the virtual connection operational domain. This distribution of information enables a routing apparatus in one sub-domain to dynamically route a virtual connection toward a destination in a different sub-domain.

Abstract: Virtual connection route selection apparatus and techniques are disclosed. At a communication traffic routing apparatus, metric information associated with multiple different routes for a virtual connection, such as a PseudoWire, toward a destination is collected. The metric information may be collected from one or more remote route computation elements capable of computing routes for virtual connections between the routing apparatus and other routing apparatus over an underlying communication system, or during actual establishment of the virtual connections, for example. An initial or re-optimized route for a virtual connection can then be selected at the routing apparatus based on the collected metric information. In some embodiments, although the virtual connection routes are paths computed by Path Computation Elements (PCEs), actual path selection decisions are distributed to routers.

Abstract: A method for testing connectivity of a multi-segment pseudo-wire in a packet switched network, the method comprising: (a) sending an echo request message from a first provider edge device to a second provider edge device for a first segment of the multi-segment pseudo-wire between the first provider edge device and the second provider edge device; and, (b) receiving an echo reply message from the second provider edge device in response to the echo request message, the echo reply message: confirming connectivity of the first segment; indicating whether there is a second segment in the multi-segment pseudo-wire between the second provider edge device and a third provider edge device; and, if there is a second segment, including information pertaining to the second segment.

Abstract: The present invention provides a system and method for providing a different quality of service to a flow associated with an aggregate flow is provided. For an embodiment, the method comprises scheduling a plurality of data traffic flows in a communication network, the method comprising: (i) scheduling data traffic flows in a first category of data traffic, said first category of data traffic having a first bandwidth capacity associated therewith; (ii) determining whether any portion of said first bandwidth capacity is unused by data traffic flows in said first category of data traffic; and (iii) scheduling data traffic flows in a second category of data traffic providing said unused portion of said first bandwidth capacity for use for said data traffic in said second category.

Abstract: A method and system for detecting and controlling congestion in a multi-port shared memory switch in a communications network. The proposed congestion management scheme implements a local and a global congestion monitoring process. The local monitoring process monitors the queue depth. When the queue depth for any queue exceeds a queue length threshold a congestion control mechanism is implemented to limit incoming data traffic destined for that queue. Additionally, the global congestion monitoring process monitors the shared memory buffer and if the traffic thereto exceeds a shared memory buffer threshold a congestion control mechanism limits incoming traffic destined for any output queue which has been exceeding a fair share threshold value.

Abstract: The invention provides a method for negotiating datapath treatment for traffic sourced from a first communications network over an end-to-end path in respect of a path segment provided for said traffic in a second communications network, the path segment being requested for a first node of the second communications network and being targeted to a second node of the second communications node. The method comprises: for the first node, notifying that a datapath capability for the path segment is one for selection for the second node; communicating datapath capabilities associated with the first node; selecting, for the second node, a datapath capability from the datapath capabilities so communicated; communicating the datapath capability so selected for the second node back to the first node; and wherein the path segment is established using a signaling protocol of the second communications network. The invention may also be implemented in a corresponding communications node.

Abstract: In a method of fair queue servicing at a queuing point in a multi-service class packet switched network, incoming packets are received in buffers and outgoing packets are scheduled by a weighted fair queue scheduler. Real-time information of buffer usage along with the minimum bandwidth requirement is used to dynamically modify the weights of the weighted fair queue scheduler.

Abstract: The present invention provides a system and method for providing a different quality of service to a flow associated with an aggregate flow is provided. For an embodiment, the method comprises scheduling a plurality of data traffic flows in a communication network, the method comprising: (i) scheduling data traffic flows in a first category of data traffic, said first category of data traffic having a first bandwidth capacity associated therewith; (ii) determining whether any portion of said first bandwidth capacity is unused by data traffic flows in said first category of data traffic; and (iii) scheduling data traffic flows in a second category of data traffic providing said unused portion of said first bandwidth capacity for use for said data traffic in said second category.

Abstract: A method and apparatus for scheduling and servicing events using a calendar structure is described. In accordance with one preferred embodiment of the present invention, a calendar structure is provided to implement work-conserving methods (for example, queuing, such as fair queuing, or, as one specific example, weighted fair queuing (WFQ)). Such a calendar structure preferably provides two slots per tier and uses a temporal pointer based on virtual time. In accordance with another preferred embodiment of the present invention, a calendar structure is provided to implement shaping of flows of information. Such a calendar structure preferably provides one slot per tier and uses a temporal pointer based on real time. For scheduling, a preferred occurrence time at which an event is preferred to occur is calculated.

Abstract: The method of the invention includes the step of transmitting a priority indicator containing information indicating the priority of network traffic over a connection to a downstream node in a communications network. The downstream node has a queue for queuing traffic received over the connection and the queue has an adjustable discard range. After transmitting the priority indicator, the network traffic is transmitted over the connection. When the priority indicator is received at the downstream node the discard range is adjusted to correspond to the priority indicated in the priority indicator. At the downstream node the network traffic is stored in the queue if a queue congestion measure is outside the discard range and discarded if the queue congestion measure is within the discard range. The priority indicator may be a Resource Management cell or may be provided in the header of a cell carrying the network traffic.

Abstract: In source routed or hop-by-hop routed protocol communication networks, when congestion is detected at a certain network element, a notification message is sent to nodes. The nodes keep track of congestion condition and generally have knowledge of the congestion, thereby allowing them to make more intelligent routing decisions, i.e., rate controlling messages, routing traffic around congestion, regulating admission at the edge of the network. The intelligent routing decision is based on the congestion condition indicated by a restriction level which is periodically and dynamically updated.

Abstract: A method and system for detecting and controlling congestion in a multi-port shared memory switch in a communications network. The proposed congestion management scheme implements a local and a global congestion monitoring process. The local monitoring process monitors the queue depth. When the queue depth for any queue exceeds a queue length threshold a congestion control mechanism is implemented to limit incoming data traffic destined for that queue. Additionally, the global congestion monitoring process monitors the shared memory buffer and if the traffic thereto exceeds a shared memory buffer threshold a congestion control mechanism limits incoming traffic destined for any output queue which has been exceeding a fair share threshold value.

Abstract: In a method of fair queue servicing at a queuing point in a multi-service class packet switched network, incoming packets are received in buffers and outgoing packets are scheduled by a weighted fair queue scheduler. Real-time information of buffer usage along with the minimum bandwidth requirement is used to dynamically modify the weights of the weighted fair queue scheduler.

Abstract: In a method of fair queue servicing at a queuing point in a multi-service class packet switched network, incoming packets are received in buffers and outgoing packets are scheduled by a weighted fair queue scheduler. Real-time information of buffer usage along with the minimum bandwidth requirement is used to dynamically modify the weights of the weighted fair queue scheduler.