Cisco Technology, Inc.

Francois Edouard Tallet

Norman William Finn

Lionel Florit

Robert W Klessig

Ali Sajassi

Pauline Shuen

Shekher Bulusu

Munish Mehta

Robert Charles Meier

Ronak K Desai

Ayan Banerjee

Varun A Shah

Rohit Sharma

Tameen Khan

Ramkumar Parameswaran

In one embodiment, a first multiple spanning tree (MST) region configuration for an MST process may be maintained at a switch in a computer network, where the first configuration has a virtual local area network (VLAN)-to-instance (VI) mapping that maps each of one or more VLANs to one of one or more MST instances in the MST region. The switch may subsequently receive a second MST region configuration that has a different VI mapping than the first configuration, and may determine one or more VLANs of the second configuration that have a different VI mapping from the first configuration ('affected VLANs'). Accordingly, in response to a trigger to apply the second configuration at the switch, the affected VLANs are blocked for a delay, and the second configuration may be applied at the switch without restarting the MST process.

Minimum disruption MST reconfiguration (MDMR)

Embodiments provide a method, network device, and computer program product for optimizing traffic in a link-state network distributed across a plurality of sites. The method, network device, and computer program product include receiving a multi-destination message at a first node within the link-state network. Additionally, the method, network device, and computer program product include identifying a plurality of multi-destination trees within the network, each tree having a respective root node. The method, network device, and computer program product determine a plurality of cost values corresponding to each of the plurality of multi-destination trees, based on one or more links along a shortest path from the first node to the respective root node of each tree. Based on the determined cost values, the method, network device, and computer program product select one or more of the multi-destination trees and transmit the multi-destination message using the selected tree.

Optimal tree root selection for trees spanning multiple sites

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.

Loop mitigation mechanism for Ethernet networks

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.

Mechanism to implement a layer 2 gateway

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.

Detecting and mitigating data plane bridging loops

In one embodiment, a spanning tree protocol (STP) is executed to assign a first port of an intermediate network device to a Root Port Role, a second port of the intermediate network device to an Alternate Port Role, a third port of the intermediate network device to a Designated Port Role, and a fourth port of the intermediate network device to a Backup Port Role. At least one bridge protocol data unit (BPDU) message is periodically sent from the first port assigned Root Port Role, the second port assigned Alternate Port Role and the fourth port assigned Backup Port Role, irrespective of receipt of any BPDU messages from neighboring intermediate network devices. In response to a failure to receive a BPDU message from a neighboring intermediate network device on the third port assigned Designated Port Role within a threshold amount of time, one or more actions are taken.

System and method for assuring the operation of network devices in bridged networks

Various systems and methods for integrating ring-protocol-compatible devices into network configurations that also include non-ring-protocol-compatible devices are disclosed. One such method, which can be performed by a network node that supports a ring protocol, involves generating a ring protocol packet and sending that ring protocol packet to a neighboring node. The ring protocol packet includes information, and the presence of this information within the packet causes a network device that receives the ring protocol packet to drop the ring protocol packet unless the network device supports a ring protocol. The information can include a reserved address (e.g., in the destination address field of the packet) as well as a ring protocol identifier.

System and method for integrating ring-protocol-compatible devices into network configurations that also include non-ring-protocol compatible devices

Loop mitigation mechanism for ethernet networks

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. Ports whose configuration digests differ from the configuration digests of received STP control messages are said to be in different regions.

System and method for running a multiple spanning tree protocol with a very large number of domains

Various systems and method of preventing data traffic connectivity between endpoints of a network segment are disclosed. One method involves receiving a segment protocol message from a first segment port within a network segment, which includes a plurality of network devices. In response to receipt of the segment protocol message, which can indicate whether connectivity is present between the segment endpoints via the network segment, a second segment port can be operated in a blocked state. Operating the second segment port in the blocked state prevents data plane connectivity via the network segment.

Preventing data traffic connectivity between endpoints of a network segment

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.

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.

System and method for implementing multiple ring networks using a common link

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.

Alternate spanning tree for faster indirect link failure recovery

In one embodiment, each network interface of a network device in a computer network may be classified as either a low-speed interface (e.g., wireless) or a high-speed interface (e.g., wired). Illustratively, then, low-speed interfaces may be configured (identified) as external interfaces to external links and high-speed interfaces may be configured (identified) as internal interfaces to internal links. By executing a multiple spanning tree (MST) protocol at the network device with other network devices in the computer network, network devices interconnected with internal links are in a same MST region and internal links within an MST region are preferred over external links between MST regions.

Growing community of inventors

Santa Clara, CA, United States of America

Francois Edouard Tallet