A permutated ring network includes a plurality of bi-directional source-synchronous ring networks, each having a plurality of data transport stations, and a plurality of communication nodes. Each of the communication nodes is coupled to one of the data transport stations in each of the plurality of bi-directional source-synchronous ring networks.

Continuance in quality level of an input timing signal may be provided. Clock source reference timing information may be receive by a first node from a second node as an input. The first node may be downstream from the second node. Then the first node may receive an event message associated with a future event associated with the second node. The first node may then refrain, for a period of time in response to receiving the event message, from switching the input for clock source reference timing information to a source other than the second node.

An on-board communication system includes an optical coupler that includes multiple optical transmission lines, and multiple on-board devices that are capable of communicating with each other with the optical coupler interposed therebetween.

A method includes receiving, by a first node on a first port of the first node, a first packet from a second node; and when the first packet carries a first flag, avoid selecting, by the first node and when selecting a clock source, a clock source corresponding to the first port, where the first flag indicates that time synchronization of the second node is uncertain.

A user station for a bus system and a method for transmitting a message at different bit rates in a bus system is provided. The user station includes a communication control unit for creating a message for at least one further user station of the bus system. The communication control unit is designed to provide in the message a first phase to be transmitted at a first bit rate, and to provide a second phase to be transmitted at a second bit rate, which is faster or slower than the first bit rate. The communication control unit is designed to provide in the message between the first and second phase a predetermined bit pattern for a bit rate switchover between the first and second bit rate. The predetermined bit pattern includes, both before and after the bit rate switchover, a flank for synchronization.

A network device synchronization method is provided. In various embodiments, a first SSM and a second SSM are received. The first SSM carries a first SSM code indicating a quality level of a first clock source and a first eSSM code indicating the quality level of the first clock source, the second SSM carries a second SSM code indicating a quality level of a second clock source. The second SSM lacks an eSSM code indicating the quality level of the second clock source, and a value of the first SSM code is equal to a value of the second SSM code. When a value of the first eSSM code is less than 0xFF, calibrating a frequency of the network device based on a timing signal of the first clock source.

Using timing delays and values associated with plant information between a CMTS, R-PHY device or a remote MACPHY device and user devices on a network to determine the distance between a head end device, for example a CMTS, R-PHY device or a remote MACPHY device and an end-user device such as cable modem in order to alert to a stolen, outdated, misplaced or otherwise at-risk end-user device.

A system on chip (SoC) includes a plurality of intellectual property (IP) blocks and a clock management unit (CMU) configured to perform clock gating on at least one of the IP blocks. The IP blocks and the CMU interface with one another using a full handshake method. The full handshake method may include at least one of the IP blocks sending a request signal to the CMU to begin providing a clock signal or to stop providing the clock signal, and the CMU sending an acknowledgement signal to the corresponding IP block in response to receipt of the request signal.

Techniques that provide link establishment between a radio equipment controller (REC) and a radio equipment (RE) in a fronthaul network are described herein. In one embodiment, a method includes performing, Common Public Radio Interface (CPRI) Layer 1 (L1) link auto-negotiation operations to establish a CPRI link between the REC and RE. A proxy slave may achieve a hyper frame number (HFN) synchronization with the REC at a link bit rate for a first CPRI bit stream and communicate the first CPRI bit stream and the link bit rate to a proxy master. The proxy master may communicate a second CPRI bit stream to the proxy slave to transmit to the REC. The L1 link auto-negotiation operations are completed and CPRI link is established between the REC and the RE when the REC achieves a HFN synchronization for the second CPRI bit stream.

Embodiments describe monitoring network activity and behavior of authorized clocks to identify suspicious activity, and in response, removing a clock for an authorized clock list. In one embodiment, a network monitor detects changes in profiles corresponding to the authorized clocks such as a disconnecting from a port, changing a network location, unexpected changes in the clock signal, changes to the clock ID or MAC address, and the like. If the network monitor deems these changes suspicious, it removes the clock from the authorized clock list. When the current master clock fails, the PTP endpoints select a new master clock only if that clock is included in the authorized clock list. In this manner, the network monitor can constantly update the authorized clock list to ensure it contains only clocks that have not been tampered with or replaced with rogue clocks.