Abstract: In a PON system with WDM, at the time of initial setting, each ONU negotiates with an OLT, and automatically acquires a wavelength which can be used by the ONU. One wavelength for negotiation of assigned wavelength is fixed as a default, and a newly connected ONU first uses the wavelength. The OLT 200 includes a plurality of light sources for downstream communication. The ONU 300 includes a wavelength variable filter selectively receiving one of wavelengths of downstream communication, and a wavelength variable light source selectively emitting light of one of plural wavelengths for upstream communication. The ONU 300 uses a transmission wavelength (for example, ?u32) for negotiation and transmits a wavelength assignment request 1000 to the OLT 200. The OLT 200 selects a wavelength ?u1 to be assigned from unused wavelengths, and transmits wavelength information to the ONU 300. The OLT 200 and the ONU 300 communicates using the notified wavelengths.

Abstract: An input interface segments a variable length packet into plurality of fixed length cells and generates an internal switching information based on the header information of the variable length packet. The input interface transmits the information to a switch and, after that, transmits the cells as the following cells of the information to the switch. The switch performs switching processing to the succeeding cells based on the information. Therefore, the information is not added to the cells. When an input interface starts to transmit cells generated from a packet to its destination output interface through the switch, the switch is reserved until all the cells arrive at the output interfaces.

Abstract: A station-side apparatus adapted for use in a passive optical network (PON) system is disclosed, which remotely collects inside information of optical network terminals (ONTs) even before completion of start-up of an optical network unit (ONU), permits an obstruction-detected ONU to send out an emergency notification message to the station-side apparatus, e.g., optical line terminal (OLP), and permits the OLT that received this message to interrupt the transmission of an upload signal toward another ONU after the elapse of a fixed length of time while at the same time receiving information from the obstruction-suffering ONU to thereby facilitate cut-and-divide or “segmentation” of obstruction. A subscriber-side device for use in the PON system is also disclosed.

Abstract: In a PON system by WDM, IP broadcast can be received without oppressing a band used by a user for Internet communication. An OLT provides a first wavelength received in common by respective ONUs and plural second wavelengths by which the OLT and the respective ONUs perform communication individually. With respect to signals in the downstream direction, each of the OLTs includes a transmitter to transmit the first wavelength and plural transmitters to transmit the second wavelengths used for the individual communication with the respective ONUs. Each of the ONUs includes a receiver to receive the first wavelength and a receiver to receive the second wavelength used in the ONU itself. The OLT transmits data of the IP broadcast by the first wavelength and transmits individual data of each of the ONUs by the second wavelength corresponding to the ONU.

Abstract: An optical access system capable of avoiding cutoffs or interruption in the periodically transmitted signals that occur during the ranging time is provided. A first method to avoid signal cutoffs is to stop periodic transmit signals at the transmitter during the ranging period, and transmit all the periodic transmit signals together when the ranging ends, and buffer the signals at the receiver to prepare for ranging. A second method is to fix definite periods ahead of time for performing ranging, then cluster the multiple periodic transmit signals together in sets at the transmitter and send them, and then disassemble those sets back into signals at the receiver. The transmitting and receiving is then controlled so that the transmit periods do not overlap with the ranging periods. In this way an optical access system is provided that can send and receive signals requiring periodic transmissions without interruption even during ranging operation.

Abstract: An analysis unit which effectively detects incidents on the basis of events detected by a security unit such as an intrusion detection system (IDS) or a firewall (FW) installed in a network stores statistical information that is frequency-distributed information of event information obtained from the collection unit, frequency component information obtained by frequency-analyzing the statistical information and the result obtained by making analysis on the basis of the frequency component. The collection unit collects and normalizes event log information outputted by IDS or FW to be stored in an event database (DB). An alert notification unit includes an alert database (DB) for storing an alert instruction transmitted from the analysis unit and an alert notification destination and reports occurrence of incidents to a manager or the like in accordance with the instruction.

Abstract: In a PON system by WDM, IP broadcast can be received without oppressing a band used by a user for Internet communication. An OLT provides a first wavelength received in common by respective ONUs and plural second wavelengths by which the OLT and the respective ONUs perform communication individually. With respect to signals in the downstream direction, each of the OLTs includes a transmitter to transmit the first wavelength and plural transmitters to transmit the second wavelengths used for the individual communication with the respective ONUs. Each of the ONUs includes a receiver to receive the first wavelength and a receiver to receive the second wavelength used in the ONU itself. The OLT transmits data of the IP broadcast by the first wavelength and transmits individual data of each of the ONUs by the second wavelength corresponding to the ONU.

Abstract: In a mobile communication system having an ATM-processed transfer path, a non-instantaneous interrupt handover can be realized. In a mobile communication network including an ATM-processed transfer path, when a mobile station is moved between cells during communication, frames are received to be identified by a mobile switching center. The frames contain the same data received from both base stations covering the cell range at asynchronous timing different from each other. A selection is made of header information with the lowest error rate from the header information of these frames. The frames are connected at instructed timing. Also, the frames to be transmitted to a plurality of base stations are duplicated, and then transmission timing is specified from these header information. These duplicated frames are transmitted at the specified transmission timing, so that the non-instantaneous interrupt handover is carried out.

Abstract: Provided is an optical access system comprising: an optical line terminal connected to another network; a plurality of optical network units, each connected to a user terminal; and at least one of an optical switching unit and an optical splitter, which is installed between the optical line terminal and the plurality of optical network units. The optical line terminal allocates a length of time to a discovery phase for detecting the plurality of optical network units, and a length of time to data transmission phases for transferring data from the plurality of optical network units; and changes a ratio of the length of time of the discovery phase to the length of time of the data transmission phases so that the length of time of the discovery phase is shortened in the case where a number of the optical network units that are registered in the optical line terminal increase.

Abstract: Disclosed herewith is a PON system and a bandwidth controlling method capable of controlling congestion with use of an upstream bandwidth in a PON section efficiently when congestion occurs in a gateway (GW) connected to an OLT. An OLT connected to a plurality of ONUs through a passive optical network (PON) and to a gateway (GW) through a communication line, when receiving a congestion occurrence notice indicating a congestion occurred output number from a GW, identifies the identifier of the ONU that is using a GW output line having the congestion output port number and shifts the bandwidth controlling of the PON section in a normal mode for allocating a bandwidth to each ONU normally to that in a bandwidth suppression mode for allocating a congestion time allowable bandwidth that is less than the current bandwidth to the ONU having the identified ONU identifier and a bandwidth to each of other ONUs according to its transmission queue length.

Abstract: Provided is an optical access system, including: an optical line terminal, a plurality of optical network units and an optical switching unit. The optical line terminal sends to the optical switching unit a control frame including a switching time when the optical switching unit is to make a switch from one of the optical communication paths between the optical line terminal and the plurality of optical network units to another, and an identifier of an optical communication path to which the switch is made in order to switch the optical communication paths between the optical line terminal and the plurality of optical network units. The optical switching unit switches the optical communication paths between the optical line terminal and the plurality of optical network units based on the switching time and the identifier of the optical communication path after switching which are included in the control frame.

Abstract: A label switching type packet forwarding apparatus having a routing information table in which a forwarding type of a reception packet, output port identification information, and output routing information of a specific layer in the OSI reference model determined by the forwarding type are defined in correspondence with routing information which is found upon reception of a packet, for converting a header of a reception packet in accordance with the packet forwarding type and the output routing information obtained by a table search.

Abstract: In a device that interworks a VLAN network and an MPLS network, a VLAN ID is associated with an MPLS label. In a device that performs interworking from a VLAN network to an MPLS network, an output MPLS label is determined from a pair of a VLAN ID and the information in the layer 3 or layer 4 header of a packet. The output MPLS label is assigned an independent value for each VLAN. In a device that performs interworking from the MPLS network to another VLAN network, the input MPLS label is associated with a VLAN ID.

Abstract: A transmission apparatus for use in fixed bandwidth communications and variable bandwidth communications. The transmission apparatus has a memory unit, which stores information contained in a frame and indicating the amount of data to be transmitted from a terminal device, a computing unit, which calculates a bandwidth amount to be assigned to the terminal device based on the data amount, and a transmission unit, which sends the calculated assigned bandwidth amount to the terminal device. The transmission apparatus is characterized in that the computing unit calculates bandwidth amounts to be assigned to different types of flow of which different transmission qualities are requested according to a priority level that is set to each flow type. The transmission apparatus is also characterized in that bandwidth is controlled by designating, instead of a necessary bandwidth amount, transmission starting timing and transmission ending timing, particularly for fixed bandwidth communication data.

Abstract: Disclosed herewith is a PON system and a bandwidth controlling method capable of controlling congestion with use of an upstream bandwidth in a PON section efficiently when congestion occurs in a gateway (GW) connected to an OLT. An OLT connected to a plurality of ONUs through a passive optical network (PON) and to a gateway (GW) through a communication line, when receiving a congestion occurrence notice indicating a congestion occurred output number from a GW, identifies the identifier of the ONU that is using a GW output line having the congestion output port number and shifts the bandwidth controlling of the PON section in a normal mode for allocating a bandwidth to each ONU normally to that in a bandwidth suppression mode for allocating a congestion time allowable bandwidth that is less than the current bandwidth to the ONU having the identified ONU identifier and a bandwidth to each of other ONUs according to its transmission queue length.

Abstract: A clock data recovery circuit that supplies stable reproduction clocks to the object respectively by shortening the time of bit synchronization with each received burst data signal regardless of jittering components included in the received burst data signal, includes an interpolator that generates a reference clock having the same frequency as that of a received burst data signal and two types of determination clocks having a phase that is different from that of the reference clock respectively; and a phase adjustment control circuit that can change the phase of the reference clock in units of M/2?. After beginning receiving of a burst data signal, the clock data recovery circuit sets a large phase change value at the first phase adjustment timing and reduces the change value in the second and subsequent phase adjustment timings, thereby realizing quick bit synchronization with the received burst data signal to generate a reproduction clock.

Abstract: A label switching type packet forwarding apparatus having a routing information table in which a forwarding type of a reception packet, output port identification information, and output routing information of a specific layer in the OSI reference model determined by the forwarding type are defined in correspondence with routing information which is found upon reception of a packet, for converting a header of a reception packet in accordance with the packet forwarding type and the output routing information obtained by a table search.

Abstract: A packet forwarding apparatus and network system for providing different types of bandwidth control services to the user; in which a packet forwarding apparatus for transferring data comprises an interface unit for sending and receiving packets, and a traffic shaper for controlling the packet transmission timing and a packet switch for sending an output to the interface unit as the destination of the received packet; and the traffic shaper uses a token bucket algorithm when transmitting a packet to guarantee the minimum frame rate, and uses a leaky bucket algorithm when limiting the peak frame rate.

Abstract: To prevent, in using a multicast DA in an OAM frame, an increase in the network bandwidth usage and in the load of node processing and a degradation of the network reliability caused by a frame being transmitted to all routes in a broadcast domain. A MAC address and other basic frame information and the MEGID are associated with each other, and the MEGID information is added to the OAM frame, and these information are transmitted from an edge node serving as an end point of an ME. In a relay node of the ME, a route control table used for OAM frame control is provided, and a filter is generated by snooping of the OAM frame. Furthermore, when the relay node does not support the OAM function, the MEGID is denoted by a VLAN tag and the route control is made using the snooping function of each VLAN tag.

Abstract: An optical access network and optical switching systems requiring no frame delay process on an optical switchboard are disclosed. Plural ONUs are connected to user terminals. An OLT communicates with an IP network through an access gateway. An optical switching unit (OSW) connects the ONUs and the OLT by switching the optical line. A control line connects the OLT and the OSW to control the optical switch change-over operation in the OSW. The optical switch port information required to generate the optical switch activation signal are concentrated in the OLT, which transmits the optical switch change-over control signal to the OSW through the control line before the transmission frame.