Abstract: A technique is provided for mitigating loops in Ethernet networks. A first port in an Ethernet device receives an Ethernet frame. The frame includes a source identifier, a destination identifier, and a Virtual Local Area Network Identifier (VLAN ID). According to various embodiments, the VLAN ID (VID) has the encoding of both a community group as well as a source bridge ID. A VID database is accessed using the destination identifier and the VID to determine whether the first port has ingress enabled. A filtering database is accessed to determine an egress port for forwarding the Ethernet frame.

Abstract: Example systems and methods associated with detecting bridging loops are described. One example apparatus includes a preliminary detection logic to detect a bridging loop in a switched network based on examining MAC moves reported by a switch in the switched network. The apparatus may also include a confirmation detection logic to confirm the bridging loop by controlling a probe to be sent into the switched network and determining that the probe looped through the switched network. The apparatus may also include a response logic to selectively control switches in the network to break the bridging loop by selectively blocking data plane traffic while allowing control plane traffic.

Abstract: A technique is provided for mitigating loops in Ethernet networks. A first port in an Ethernet device receives an Ethernet frame. The frame includes a source identifier, a destination identifier, and a Virtual Local Area Network Identifier (VLAN ID). According to various embodiments, the VLAN ID (VID) has the encoding of both a community group as well as a source bridge ID. A VID database is accessed using the destination identifier and the VID to determine whether the first port has ingress enabled. A filtering database is accessed to determine an egress port for forwarding the Ethernet frame.

Abstract: A technique is provided for mitigating loops in Ethernet networks. A first port in an Ethernet device receives an Ethernet frame. The frame includes a source identifier, a destination identifier, and a Virtual Local Area Network Identifier (VLAN ID). According to various embodiments, the VLAN ID (VID) has the encoding of both a community group as well as a source bridge ID. A VID database is accessed using the destination identifier and the VID to determine whether the first port has ingress enabled. A filtering database is accessed to determine an egress port for forwarding the Ethernet frame.

Abstract: Methods and apparatus that form the basis of an alternate spanning tree protocol that may be used, for example, to identify rings within a properly converged network configured by the spanning tree protocol (STP) or rapid spanning tree protocol (RSTP) are provided. With the knowledge of these rings, the alternate spanning tree has predetermined an alternate port that can restore connectivity without further computation in case of a link failure, thereby providing for extremely fast reconvergence.

Abstract: Example systems and methods associated with detecting bridging loops are described. One example apparatus includes a preliminary detection logic to detect a bridging loop in a switched network based on examining MAC moves reported by a switch in the switched network. The apparatus may also include a confirmation detection logic to confirm the bridging loop by controlling a probe to be sent into the switched network and determining that the probe looped through the switched network. The apparatus may also include a response logic to selectively control switches in the network to break the bridging loop by selectively blocking data plane traffic while allowing control plane traffic.

Abstract: Methods and apparatus that form the basis of an alternate spanning tree protocol that may be used, for example, to identify rings within a properly converged network configured by the spanning tree protocol (STP) or rapid spanning tree protocol (RSTP) are provided. With the knowledge of these rings, the alternate spanning tree has predetermined an alternate port that can restore connectivity without further computation in case of a link failure, thereby providing for extremely fast reconvergence.

Abstract: A system and method runs a multiple spanning tree protocol (MSTP) in a computer network having a very large number of bridge domains. The computer network includes a plurality of intermediate network devices, each having a plurality of ports for forwarding network messages. Within each device, a plurality of bridge domains are defined, each bridge domain is identified by a Virtual Local Area Network (VLAN) Identifier (VID), and one or more device ports. For each port, a separate mapping of VIDs to Multiple Spanning Tree Instances (MSTIs), based on the bridge domains defined at the port, is established. Each mapping is converted to a port-based configuration digest, which is entered into Spanning Tree Protocol (STP) control messages sent from the respective port. Ports receiving STP control messages whose configuration digest values that match the configuration digests values computed for the ports are said to be in the same Multiple Spanning Tree region.

Abstract: A system in an operating system of a first network device for using Spanning Tree Protocol to determine a port of a device in a first administrative domain to transmit data between the first network device and a second administrative domain. The system determines each port in a device of the first administrative domain connected to a bridge for transmitting between the first network device and the second administrative domain. A priority of each these ports is determined by priority data. The port having a highest priority is then selected to transmit said data between said first network device and said second administrative domain.

Abstract: A system and method creates multiple, symmetric spanning trees within a network. Bridges within the network generate, send and process Spanning Tree Protocol (STP) control messages that are updated as they are propagated across the network to reflect the paths followed by the messages. The bridges, moreover, utilize the path indication value of received STP control messages to compute the spanning trees. The path indication values are preferably derived from the sum of Bridge Identifiers (IDs) corresponding to the bridges through which the STP control message has passed from the root bridge to the current bridge processing the STP control message. Each bridge also tags newly received messages with the Virtual Local Area Network (VLAN) identifier (VID) associated with the spanning tree for which the bridge is the root, thereby causing the messages to follow more optimal paths through the network.

Abstract: Various systems and methods for implementing virtual ports within ring networks are disclosed. For example, one method involves allocating a logical port that corresponds to a first port and a second port and instantiating a spanning tree protocol instance. The first port and the second port are both assigned to a first ring network. The spanning tree protocol instance selectively blocks the logical port; however, the spanning tree protocol instance is unable to block the first port independently of blocking the second port. Events (e.g., link failures and recoveries) that occur within the ring network are communicated to spanning tree by transitioning the state of the logical port in response to receiving a ring protocol control packet. The spanning tree protocol instance initiates a bridge protocol data unit (BPDU) exchange from the logical port in response to a transition in the state of the logical port.

Abstract: Various systems and methods for implementing virtual ports within ring networks are disclosed. For example, one method involves allocating a logical port that corresponds to a first port and a second port and instantiating a spanning tree protocol instance. The first port and the second port are both assigned to a first ring network. The spanning tree protocol instance selectively blocks the logical port; however, the spanning tree protocol instance is unable to block the first port independently of blocking the second port. Events (e.g., link failures and recoveries) that occur within the ring network are communicated to spanning tree by transitioning the state of the logical port in response to receiving a ring protocol control packet. The spanning tree protocol instance initiates a bridge protocol data unit (BPDU) exchange from the logical port in response to a transition in the state of the logical port.

Abstract: A system and method assures the proper and continued operation of intermediate network devices, such as bridges, in a computer network. The bridge includes a spanning tree protocol (STP) engine, which is configured to have a bridge assurance (BA) sub-engine. The STP engine assigns the bridge's ports to one of a Root, Alternate, Designated or Backup Role. The BA sub-engine directs the STP engine to issue configuration messages from all ports to which neighboring bridges are coupled, including ports assigned to the Root and Alternate roles. The BA sub-engine further looks for the receipt of BPDU messages from neighboring bridges and employs one or more timers to determine whether the neighboring bridges are continuing to operate properly.

Abstract: A method, system, apparatus, and machine-readable medium for data transmission in a segment of a network through a bridge are provided. The bridge comprises one designated forwarding port and at least one backup port. The method selects a best backup port from amongst the available backup ports. On detection of a failure of data transmission through the designated forwarding port, the data is transmitted through the best backup port without any time delay. When a failed designated forwarding port recovers from the failure of data transmission, the data is transmitted through the recovered failed forwarding port without any time delay. The system includes a selector, a detector, and a switching module to implement the above method.