Abstract: There is described a Precision Time Protocol (“PTP”) transparent clock for inter-VLAN forwarding comprising a Layer 2 switch and a PTP module. The switch includes a first port associated with a first VLAN and a second port associated with a second VLAN. The switch detects a PTP frame at the first port and the PTP module receives the PTP frame. The switch forwards the PTP frame to the second port in response to the PTP module determining that the PTP frame is a forwardable frame. For another embodiment, the switch includes a ternary content-addressable memory (“TCAM”), and the PTP module configures the TCAM to include forwarding rules. The Layer 2 switch forwards the PTP frame to the second port in response to identifying a particular forwarding rule associated with forwarding the PTP frame.

Abstract: Method and network device for providing redundancy in an industrial network includes a first port group connected to a first network segment of the industrial network, and includes a switch module that has a plurality of southbound ports, wherein at least one southbound port is connected to a corresponding end device, where each port group has a pair of redundant northbound ports connected to a link redundancy entity having two or more interlinked ports connectable to one or more south-bound ports of switch module based on network topology for enabling redundant links between end devices connected to the southbound ports and the first network segment.

Abstract: There is described a Precision Time Protocol (“PTP”) transparent clock for inter-VLAN forwarding comprising a Layer 2 switch and a PTP module. The switch includes a first port associated with a first VLAN and a second port associated with a second VLAN. The switch detects a PTP frame at the first port and the PTP module receives the PTP frame. The switch forwards the PTP frame to the second port in response to the PTP module determining that the PTP frame is a forwardable frame. For another embodiment, the switch includes a ternary content-addressable memory (“TCAM”), and the PTP module configures the TCAM to include forwarding rules. The Layer 2 switch forwards the PTP frame to the second port in response to identifying a particular forwarding rule associated with forwarding the PTP frame.

Abstract: There is described a system and method for configuring multiple PTP ports of a network device comprising an input component and a processor. A PTP port group, associated with a subset of PTP ports of the network device and with a PTP region, is identified. A PTP parameter set corresponding to the PTP port group is received and applied to each port of the subset of PTP ports associated with the PTP port group. A time exchange is performed for PTP capable devices within the PTP region. There is also described a PTP network device comprising a first transparent clock, a second transparent clock, and a boundary clock. The first transparent clock performs time exchange within the first PTP region. The second transparent clock performs time exchange within the second PTP region. The boundary clock performs time exchange between the first and second PTP regions.

Abstract: Method and network device for providing redundancy in an industrial network includes a first port group connected to a first network segment of the industrial network, and includes a switch module that has a plurality of southbound ports, wherein at least one southbound port is connected to a corresponding end device, where each port group has a pair of redundant northbound ports connected to a link redundancy entity having two or more interlinked ports connectable to one or more south-bound ports of switch module based on network topology for enabling redundant links between end devices connected to the southbound ports and the first network segment.

Abstract: A method of providing a path between bridges of a first network segment. The first network segment is configured using a Spanning Tree Protocol (‘STP’). The method includes providing a second network segment interconnecting first and second bridges of said first network segment. The second network segment is operable to transmit frames adherent to a High-availability Seamless Redundancy (‘HSR’) network control protocol and to discard the STP control data frames. The method also includes modifying at a first Redundancy Box (‘RedBox’) STP control data frames to form modified data frames adherent to the HSR protocol. The method also includes modifying at a second RedBox, the modified data frames to re-form the STP control data frames.

Abstract: A method of providing a path between bridges of a first network segment. The first network segment is configured using a Spanning Tree Protocol (‘STP’). The method includes providing a second network segment interconnecting first and second bridges of said first network segment. The second network segment is operable to transmit frames adherent to a High-availability Seamless Redundancy (‘HSR’) network control protocol and to discard the STP control data frames. The method also includes modifying at a first Redundancy Box (‘RedBox’) STP control data frames to form modified data frames adherent to the HSR protocol. The method also includes modifying at a second RedBox, the modified data frames to re-form the STP control data frames.

Abstract: A method of facilitating clock synchronization over redundant networks may include, when a SYNC message and a DELAY_REQ message of a PTP clock synchronization cycle are carried by different redundant networks, adjusting a timestamp associated with one of the messages to emulate carriage of the SYNC message and the DELAY_REQ message by the same redundant network. In a method of facilitating PTP clock synchronization, an indicator of an operational status of each of a pair of redundant networks for carrying messages from a slave clock to a master clock may be embedded in a PTP message destined for the slave clock. An indicator of which one of the pair of redundant networks is valid for PTP clock synchronization may be obtained from a PTP message destined for the master clock. PTP messages to the master clock may be selectively relayed based on whether the PTP messages have been received from the valid one of the redundant networks.

Abstract: A method of facilitating clock synchronization over redundant networks may include, when a SYNC message and a DELAY_REQ message of a PTP clock synchronization cycle are carried by different redundant networks, adjusting a timestamp associated with one of the messages to emulate carriage of the SYNC message and the DELAY_REQ message by the same redundant network. In a method of facilitating PTP clock synchronization, an indicator of an operational status of each of a pair of redundant networks for carrying messages from a slave clock to a master clock may be embedded in a PTP message destined for the slave clock. An indicator of which one of the pair of redundant networks is valid for PTP clock synchronization may be obtained from a PTP message destined for the master clock. PTP messages to the master clock may be selectively relayed based on whether the PTP messages have been received from the valid one of the redundant networks.

Abstract: A method and a bridge operative to notify other bridges connected to a network of a root bridge failure by detecting a failure in a connection to the root bridge and generating a root failure suspicion notification (RFSN) bridge protocol data unit (BPDU) that includes a standard Rapid Spanning Tree BPDU portion and a failed root identifier portion uniquely identifying the root bridge which is suspected of failing. The bridge propagates the RFSN BPDU to adjacent bridges in the network to notify them of the failure.

Abstract: An active loop-free topology established by a Rapid Spanning Tree Algorithm and Protocol (RSTP) emanates from an original root bridge. Upon a bridge directly connected to the root bridge suspecting a failure in the root bridge, the bridge directly connected to the root bridge generates a Root Failure Suspicion Notification (RFSN) Bridge Protocol Data Unit (BPDU) comprising a standard Rapid Spanning Tree (RSTP) BPDU portion and a compressed failed root identifier portion uniquely identifying the root bridge which is suspected of failing. The RFSN BPDU is propagated amongst the bridges in the network. The bridges which can identify a flag in the standard RSTP BPDU portion of the RFSN BPDU decompress the compressed failed root identifier and compare it to the stored root identifier at each bridge. If the received failed root identifier in the RFSN BPDU corresponds to the stored root identifier of the bridge, the bridge deletes the stored root identifier.