53 results about "Circuit Emulation Service" patented technology

A centralized clock distribution mechanism for synchronous TDM communications traffic transported over asynchronous networks such as Ethernet networks. The centralized clocking mechanism of the present invention distributes a high accuracy central clock source to a plurality of CES modules over an Ethernet network. Clock synchronization information based on a high quality clock reference source is distributed to circuit emulation service (CES) modules in the network. CES modules receive the clock synchronization information and use it to reconstruct a local clock. A plurality of clock distributors provide clock redundancy whereby each CES module selects the best clock source to use in reconstructing the local clock.

The present invention establishes a circuit emulation service (CES) over an internet protocol (IP) network based on properties of the IP network. The CES emulates a circuit from a local interworking function to a remote interworking function. Data that is received at a constant bit rate at the local interworking function is encapsulated into a number of IP packets configured according to the CES. The IP packets are transported from the local interworking function to the remote interworking function according to the CES. In one embodiment, each IP packet also includes data segments for simultaneously encapsulating multiple constant bit rate circuits. In another embodiment, each data segment includes a separate CES circuit header.

Precision Time Protocol (PTP) emulation service for a data communication network of a type that is adapted to support circuit emulation services (CES). The PTP emulation service enables seamless PTP-style clock synchronization over such a network using any combination of legacy switches, PTP boundary switches and PTP switches. The PTP emulation service is delivered through the expedient of external PTP emulation devices that are associated with legacy switches and PTP boundary switches.

An Asynchronous Transfer Mode (ATM)-based distributed virtual tandem switching system is provided in which a network of ATM-based devices is combined to create a distributed virtual tandem switch. The system includes an ATM switching network that dynamically sets up individual switched virtual connections. The system also includes a trunk interworking function (T-IWF) device and a centralized control and signaling interworking function (CS-IWF) device. The trunk interworking function device converts end office voice trunks from TDM channels to ATM cells by employing a structured circuit emulation service. The centralized control and signaling interworking function device performs call control functions and interfaces narrowband signaling and broadband signaling for call processing and control within the ATM switching network. Consequently, the ATM based distributed virtual tandem switching system replaces a standard tandem switch in the PSTN.

A clock synchronization backup mechanism is disclosed for maintaining clock synchronization during periods of degraded synchronization. The clock synchronization backup mechanism includes a jitter buffer having a fill value at a given sample time which is compared with a threshold. When the jitter buffer fill value exceeds the threshold, a non-normal condition is registered and the local clock frequency is set to a combination of a long-term frequency setting plus a threshold sensitive frequency adjustment. The clock synchronization backup mechanism is particularly useful for overcoming residual errors accumulated due to temperature change, oscillator degradation, and a variety of other system perturbations problematical for clock synchronization mechanisms known in the art.

A timestamp-based all digital phase locked loop is utilized for clock synchronization for Circuit Emulation Service (“CES”) over packet networks. The all digital phase locked loop at a CES receiver includes a phase detector, a loop filter, a digital oscillator and a timestamp counter. The all digital phase locked loop enables the CES receiver to synchronize a local clock at the receiver with a clock at a CES transmitter, where indications of transmitter clock signals are communicated to the receiver as timestamps. The phase detector is operable to compute an error signal indicative of differences between the timestamps and a local clock signal. The loop filter is operable to reduce jitter and noise in the error signal, and thereby produce a control signal. The digital oscillator is operable to oscillate at a frequency based at least in-part on the control signal, and thereby produce a digital oscillator output signal. The timestamp counter operable to count pulses in the digital oscillator output signal, and output the local clock signal.

A system and method for managing information communication in a network includes a plurality of network nodes. A plurality of circuit emulation data flows are established between a first network node and at least a second network node. Different data transmission rates are assigned to each circuit emulation data flow such that the frequency of communicated packets is different at least for each circuit emulation data flow used for timing recovery to make the plurality of circuit emulation data flows substantially independent of each other. For example, different frame rates can be assigned to synchronous backhaul transmission links such that the frequency of the backhaul transmission rates is substantially independent of the circuit emulation flow rates.

A method and apparatus are provided for providing CES using both Ethernet and MPLS networks. TDM data is packetized and Ethernet encapsulated, and then MPLS encapsulated. Following insertion into an MPLS core network, the packet is routed to a destination MPLS router using MPLS routing. The MPLS encapsulation is then removed, and the resulting Ethernet frame inserted into a destination Ethernet network. The Ethernet frame is routed to a destination Ethernet port using Ethernet routing. The TDM data is extracted, and inserted into the appropriate TDM channel. The invention allows inexpensive Ethernet equipment to be used at the boundary with the TDM network, and a reliable MPLS network with its QoS functionality to be used for any long-haul part of the CES.

A system and method are provided for implementing CESOP inexpensively yet effectively implemented across an MPLS or an IP network. A Zarlink chip provides CESOP functionality, providing a TDM pseudowire by converting TDM streams into Ethernet packets. These Ethernet packets can be processed by a Marvell chip, which has the ability to perform QoS functions on the packets. The Marvell chip converts the Ethernet packets into MPLS or IP packets for transmission over a packet network. Use of a single virtual circuit label, invisible to the packet network for routing purposes, within the Ethernet packet allows Marvell chips at each end of the emulated circuit to tie traffic to a particular customer and to thereby apply appropriate QoS constraints.

It is disclosed a method for implementing a circuit emulation service through a packet-switched network, wherein the packet-switched network cooperates with a first interface and a second interface suitable to connect a first user and a second user, respectively, to the packet-switched network. The method comprises: a) at the first interface, receiving a TDM flow from the first user; b) converting the TDM flow in packets formatted according to the circuit emulation service, wherein at least one of the packets comprises a header in turn comprising a redundant field; c) compressing the header into a compressed header by processing the redundant field, and forming a compressed packet comprising the compressed header; d) transmitting the compressed packet through the packet-switched network to the second interface.

The invention discloses a configuration method of circuit emulation service (CES) in a passive optical network (PON). The method comprises the following steps: according to a CES template prestored on an optical link terminal (OLT), CES template information is configured on the OLT; pseudo-wire parameter is configured on the OLT; when an optical network unit (ONU) on the opposite terminal of the pseudo-wire is on-line, the OLT issues the CES template information and pseudo-wire parameter configured on the terminal to the ONU; the ONU performs the local configuration of the CES pseudo-wire according to the received CES template information and pseudo-wire parameter; after the configuration succeeds, a successful configuration message is reported to the OLT; after the OLT receives the successful configuration message sent by the ONU, the OLT issues a target parameter query message to the ONU; the ONU reports the target parameter stored in the local terminal to the OLT; and the OLT obtains the target parameter in the local configuration. The invention also discloses a configuration system of the CES in the PON.

The embodiment of the invention discloses a data transmission method, which comprises the following steps of: scheduling a circuit emulation service (CES) message from a buffer queue to a CES queue; scheduling a data message from the buffer queue to a data queue; sequentially performing slicing processing on a first data message from the data queue; performing encapsulation processing on a CES message in the CES queue and the sliced first data message, wherein encapsulation information comprises message type information; and competitively transmitting the encapsulated CES message and the encapsulated sliced first data message. The embodiment of the invention also discloses the data transmission method, a data transmission device and a data transmission system. The first data message is sliced, and the CES message can be instantly transmitted only after the transmission of a slice is finished without waiting for the complete transmission of the whole data message, so the problem of jitter of CES can be well solved.

Network timing is derived from the PSTN and distributed through the network to gateways capable of deriving timing from the incoming UDP stream. The derived timing has the correct frequency for voice telephony without using external timing sources or extraneous hardware components. For example, a digital signal processor (DSP) can derive the timing from a timed TDM bus and distribute messages, such as IP messages, to other gateways or port networks. The other gateways and port networks use the incoming stream to extract the timing which is then used to time their TDM bus. The port networks and gateways can also distribute other streams to other gateways in a fan-out type of arrangement. This internally generated timing can be used, for example, for Circuit Emulated Services (CES).

The invention provides a multiplex section protection (MSP) method based on a multicast way, and aims to protect emulation disks in a circuit emulation service. The MSP protection method comprises the following steps: setting a receiving/transmitting switch on each port of each emulation disk to receive/transmit a service; during service configuration on a corresponding port, judging whether or not the corresponding port is configured with MSP protection, if not, establishing a service on the corresponding port, and if so, judging whether or not the port is a master port according to a set master-standby port relation; if so, establishing a service on the master port, configuring the service on a corresponding standby port according to the set master-standby port relation, and setting a receiving/transmitting switch on the standby port according to an MSP protection way; if not, establishing a service on the standby port. According to the method, the service configured on the emulation disk on which the main port is positioned is configured on the emulation disk where the standby port is positioned in the multicast way, so that convenience is brought to service switching of the master and standby ports. The invention further provides an MSP protection system based on the multicast way.

The invention provides a lossless transmission method of a CES (Circuit Emulation Service). The lossless transmission method mainly comprises the following steps: 1) enabling a CES packet to be simultaneously sent to main and standby paths for transmission; 2) enabling a receiving side to simultaneously receive the CES packet from the main and standby paths; 3) enabling a packet buffer of the receiving side to process the received CES packet, wherein a processing method includes an SN (Sequence Number) detection mechanism: receiving a CES packet having an expected SN from any path, putting theCES packet into the packet buffer, and then if a CES packet having a same SN is received from another path again, abandoning the CES packet received later; and 4) sending the CES packet in the packetbuffer to a user device, thereby implementing lossless transmission of the CES packet.

Methods and apparatus are provided for circuit emulation services over cell and packet networks. A constant bit rate traffic stream is mapped to one of a cell and packet structure. The constant bit rate traffic stream is mapped to one or more cells and the one or more cells are selectively translated to one or more packets if a packet stream is selected. In addition, one of a received cell and packet stream are mapped to a constant bit rate traffic stream. The packet stream is selectively translated to one or more cells and the one or more cells are translated to the constant bit rate traffic stream. A clock can optionally be recovered from the received cell or packet stream.

A system and method for realizing network synchronization by packet network mainly includes: restoring the clock signal from the superior processing equipment data link of the packet network, and sending it to the subordinate processing equipment; realizing the synchronization of said processing equipment based on said clock signal. It can realize the uniform timing of the whole network and change the IP network without the timing into the synchronous network, which is similarly with the circuit network, with high bandwidth. It can not only provide a circuit simulation service, but also a multi-service with high bandwidth.

Network timing is derived from the PSTN and distributed through the network to gateways capable of deriving timing from the incoming UDP stream. The derived timing has the correct frequency for voice telephony without using external timing sources or extraneous hardware components. For example, a digital signal processor (DSP) can derive the timing from a timed TDM bus and distribute messages, such as IP messages, to other gateways or port networks. The other gateways and port networks use the incoming stream to extract the timing which is then used to time their TDM bus. The port networks and gateways can also distribute other streams to other gateways in a fan-out type of arrangement. This internally generated timing can be used, for example, for Circuit Emulated Services (CES).