The present invention is directed to a high speed packet switching network and, in particular to a method and system for minimizing the time to establish a connection between an origin and a destination node. Due to high dynamicity of the traffic on transmission links, it is important to select a routing path according to a fully up-to-date information on all network resources. The simpler approach is to calculate a new path for each new connection request. This solution may be very time consuming because there are as many path selection operations as connection set up operations. On another hand, the calculation of paths based on an exhaustive exploration of the network topology, is a complex operation which may also take an inordinate amount of resources in large networks. Many of connections originated from a network node flow to the same destination network node. It is therefore possible to take a serious benefit in reusing the same already calculated paths for several connections towards the same node. The path calculated at the time the connection is requested is recorded in a Routing Database and updated each time a modification occurs in the network. Furthermore, alternate paths for supporting non-disruptive path switch on failure or preemption, and new paths towards potential destination nodes can be calculated and stored when the connection set up process is idle. These last operations are executed in background with a low processing priority and in absence of connection request.

Method and system for minimizing the connection set up time in high speed packet switching networks

A multi-layer network element (12) for forwarding received packets from an input port to one or more output ports (38) with quality of service. When output queues (54) exceed or meet a threshold value below the queue's capacity packets are randomly discarded. When the queue becomes full, the network element determines which flow caused the queue to overflow. The priority of that flow is lowered. In a multicast packet, the packet may have different priorities at each output port. Scheduling of multiple output queues at each output port uses a weight round robin approach that allocates a weight portion of packets to transmit at each time interval. A packet is not interrupted during its transmission, even if the weight portion is met during a packet's transmission. The excess number of bytes transmitted as a result of not interrupting the packet are accounted for in the next round.

A system and method for a quality of service in a multi-layer network element

A multi-layer network element for forwarding received packets from an input port to one or more output ports. The packet is examined to look for first and second forwarding information. A packet is also assigned to a class and provided with default packet forwarding information. An associative memory is searched once for each type of information. The results from the two searches are combined with the default packet forwarding information to forward the packet to the appropriate one or more output ports. In some instances, the results of the first search dominate the forwarding decision, in other, the results of the second search dominate the forwarding decision, and in still other instances, the default information dominates.

A system and method for a multi-layer network elememt

A method for operating a computer network includes: a become_root_primary command is issued to a first router to set an ID so that a spanning tree protocol (STP) selects the first router as a primary root router; a become_root_secondary command is issued to a second router to set an ID so that STP selects the second router as a secondary root router; transitioning, in response to failure of the first router, the second router to become the root router. An enable_uplinkfast command is issued to a router, and the router selects a backup designated port for a designated port, and selects a backup root port for a root port. Ports transmit BPDU messages as heartbeat messages, and a failure to detect the BPDU messages results in a backup port assuming the role of a port not detecting the BPDU messages.

Method and apparatus for rapidly reconfiguring computer networks

A shared spanning tree protocol (SSTP) creates a plurality of spanning trees (i.e., loop-free paths) which are shared among one or more virtual local area network (VLAN) designations for data transmission within a computer network. Each shared spanning tree includes and is defined by a primary VLAN and may be associated with one or more secondary VLANs. In order to associate VLAN designation(s) with a single shared spanning tree, network devices exchange novel shared spanning tree protocol data units (SST-PDUs). Each SST-PDU corresponds to a given primary VLAN and preferably includes one or more fields which list the secondary VLAN designations associated with the given primary VLAN. The association of VLAN designations to shared spanning trees, moreover, preferably depends on which path traffic is to follow as well as the anticipated load characteristics of the various VLANs. The association of VLAN designations to shared spanning trees thus provides a degree of load balancing within the network. Data messages tagged with a particular VLAN designation are then distributed by the devices only along the shared spanning tree to which that VLAN has been associated by SSTP.

Shared spanning tree protocol

Resources for computing an active network topology in a system having a plurality of ports coupled to respective local area networks include a protocol entity coupled to the plurality of ports which communicates with protocol entities in other systems on the networks to establish the active network topology. Port state logic, coupled with the protocol entity and the plurality of ports establishes active network states for the plurality of ports. The active network states include a first network state for forwarding data and a second network state for blocking data, wherein a transition from a first network state to a second network state is executed after receiving information from the protocol entity indicating a change to the second network state. A transition from the second network state back to the first network state is executed upon expiry of a waiting interval after receiving information from the protocol entity indicating a change to the first network state, unless information indicating a change to the first network state is received within a forgetting interval after a change from the first network state to the second network state. If the information indicating such change is received prior to expiry of the forgetting interval, then the transition is executed immediately.

Michael J. Seaman

Papers

Active topology maintenance in reconfiguring bridged local area networks with state transition with forgetting interval