Abstract: A burst mode optical receiver is disclosed and includes a converter for converting a burst mode signal into a voltage signal, a bottom level detector for detecting a bottom level of an output signal from the converter, an automatic gain controller for automatically controlling the gain of the converter on the basis of the bottom level detected by the bottom level detector in order to maintain an amplitude of the output signal from the converter and generating a reset signal when the bottom level is lower than a predetermined reference value, and a power level detector for detecting a power level of the output signal from the converter and generating the reset signal and an LOS signal indicative of the presence of no input signal when the detected power level is lower than a predetermined reference value.

Abstract: A wireless power supply and method of wirelessly supplying power use light to directly supply power wirelessly to an electrical apparatus without a power cable. The wireless power supply includes: a plurality of pressure switches adapted to switch ON/OFF in response to an applied pressure; and a plurality of light emitting devices respectively connected to the plurality of pressure switches, the plurality of light emitting devices adapted to emit light to supply the power to a load in response to at least one of the pressure switches being switched ON.

Abstract: A method for monitoring traffic in a packet switched network. The packet switched network includes connections grouped in a single group; token buffers for respectively corresponding to the connections, and storing tokens generated at a predetermined token generation rate by the corresponding connection; a shared token pool for being shared among the connections, and storing the generated tokens therein when each token buffer of each connection is over a predetermined maximum size; and counters for respectively corresponding to the connections, and counting tokens stored in the shared token pool by a corresponding connection.

Abstract: Disclosed is a duobinary optical transmitter, which includes a laser source for outputting light with a predetermined wavelength; a Mach-Zehnder interferometer-type optical intensity modulator for modulating the intensity of the light according to a three-level data signal inputted through a modulation terminal; a low-pass filter for converting an inputted two-level binary data signal into a three-level data signal through an interference among codes; and, a modulator driver/amplifier for amplifying the three-level data signal and then outputting it to the modulation terminal, wherein the overall bandwidth of the low-pass filter, the modulator driver/amplifier, and the optical intensity modulator corresponds to approximately ¼ of the clock frequency of the two-level binary data signal.

Abstract: Disclosed is a duobinary optical transmission apparatus. The duobinary optical transmission apparatusenhances nonlinear and dispersion characteristics for an intermediate-long distance transmission at a high-speed transfer rate without the use an electric LPF. The duobinary optical transmission apparatus includes a light source for generating a carrier wave, a duobinary optical signal generator for receiving a Non Return to Zero (NRZ) signal and generating a modulated optical signal generated by modulating the carrier wave according to the NRZ signal, and a Return to Zero (RZ) signal generator for converting the NRZ signal into a RZ (Return to Zero) signal. Therefore, optical intensity and a phase are modulated using only a single interferometer-type optical modulator.

Abstract: A method for providing end-to-end security service in a communication network having an NAT-PT function comprises: performing security negotiation between a first node included in a first communication network having the network address translation-protocol translation function and a second node included in a second communication network operating with a protocol different from the first communication network; storing protocol translation information generated when the security negotiation is performed in the first node; and performing security transmission between the first and second nodes using the stored protocol translation information. The method transmits the address translation information to the ends in advance, thereby being capable of applying the security service using the address information on transmitting the data between hosts in the communication network using the address translation method.

Abstract: In an Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) tunneling system and method, an ISATAP tunnel which is a type of an IPv6 transition tunnel is used, even through a network address translation (NAT) region. The tunneling system for tunneling data having address formats different from one another includes: a host for encapsulating a message of a first address format in a message of a second address format; an address translator for receiving the encapsulated message of the second address format from the host, and for translating a source address of a private address format into a global address format; and a router responsive to reception of the encapsulated message of the global address format from the address translator for assigning the source address translated into the global address format as a destination address, and for transmitting to the host the message of the second address format having the assigned destination address included in prefix information.

Abstract: A gain flattening filter is provided to reduce volume and manufacturing cost of a gain flattened optical fiber amplifier, even when a required peak loss exceeds the limit of each dielectric thin film filter. The inventive gain flattening filter includes: a housing having a first opening and a second opening; a first ferrule disposed at one end of the housing, the first ferrule having an opening through which an input of an optical fiber is packaged; a second ferrule disposed at the other end of the housing, the second ferrule having an opening through which an output of the optical fiber is packaged; and, a plurality of thin film filters disposed in sequence between the first and second ferrules for flattening gain of optical signals passing therethrough.

Abstract: A Raman optical-fiber amplifier used in a wavelength-division-multiplexing optical communication system is provided. The inventive amplifier includes an optical transmitter for transmitting wavelength-division-multiplexed optical signals through an optical fiber and an optical receiver for receiving the optical signals through the optical fiber, and further comprises an erbium-doped fiber which Raman-amplifies and outputs optical signals inputted through the first end of the erbium-doped fiber amplifier connected with the optical fiber; a pumping source which outputs pump light with a predetermined wavelength so as to Raman-pump the erbium-doped fiber; and, a wavelength-selective coupler which outputs the pump light to be introduced into the erbium-doped fiber.

Abstract: An apparatus and method for transmitting multi-protocol label switching (MPLS) multicast packets over Ethernet are provided. The apparatus and method determine whether a received packet is an MPLS multicast packet; determine whether an address of the received packet exists in a database storing address information for MPLS multicast packet transmission; determine which node the MPLS multicast packet whose address exists in the database is transmitted to and allocating an MPLS label according to the address of the determined node; and map the allocated MPLS label to an Ethernet destination MAC address of the packet in order to realize simple switching by mapping an MPLS label, rather than a conventional IP address, to an Ethernet destination medium access control (MAC) address, thereby utilizing advantages of an MPLS network.

Abstract: A method of Transport Control Protocol (TCP) congestion control using multiple TCP AKCs in an integrated network including wireless links, the method including: receiving a packet retransmitted from a correspondent upon a mobile node having a packet loss in a received packet; calculating the number of acknowledgment messages to be transmitted by the mobile node; generating multiple acknowledgment messages according to the calculated number and transmitting the multiple acknowledgment messages to a transmitting node; and increasing a congestion window value corresponding to the multiple acknowledgment messages received by the transmitting node, and executing the TCP transmission.

Abstract: A network routing method for preventing packet drop or loss comprises the steps of presetting best and second routes for the same destination, determining a route for an inputted packet with reference to the preset best and second routes, selectively queuing the inputted packet to respective output queues of the preset best and second routes in accordance with whether there is congestion in the output queues of the preset best and second routes, and sequentially queuing the packets stored in the output queues of the preset best and second routes, and transporting same to output ports of corresponding routes, in accordance with an order of input thereof. A network routing apparatus comprises a forwarding table, a forwarding section, a queue management section, and a transport section for use in performing functions corresponding to the above steps.

Abstract: In a method of dynamic queue management for stable packet forwarding and a network processor element therefor, a network processor of a switch/router can stably assign a packet descriptor for packet forwarding of a local area network/wide are network (LAN/WAN) interface. The method comprises the steps of: determining whether there is a corrupted link for the purpose of processing packets for the forwarding; setting free a packet buffer and a descriptor stored in a queue of a port corresponding to the corrupted link; detecting a normal link to number corresponding output ports; and queuing the packets and descriptors corresponding to the packets to a forwarded one of the calculated ports.

Abstract: A method for managing a ternary content addressable memory (CAM) comprises the steps of: dividing the ternary CAM into parts corresponding to a number of sequence IDs determined by a packet classification rule set by a system manager; storing a packet having a priority set according to the packet classification rule in an entry storage area of the sequence IDs according to the priority; and, when an entry storage area allocated to a sequence ID where a new entry is intended to be added is completely occupied, extending the corresponding sequence ID and adding thereto the new entry, thereby controlling the ternary CAM.

Abstract: A multicast packet forwarding apparatus and method that can combine an internal processor of a multicast packet processor into a forwarding unit and a packet duplicator in order to minimize delay in the processing time of a forwarder and a packet transmitter. In the apparatus, a packet receiver is adapted to receive unicast and multicast packets. A forwarding unit has a unicast forwarder for forwarding a unicast packet to a destination when the packet receiver receives the unicast packet, and a multicast forwarder for multicasting a multicast packet to respective output interfaces when the packet receiver receives the multicast packet. A packet duplicator is adapted to convert the multicast packet output from the multicast forwarder into a several unicast packets. A packet dispatcher is adapted to reintroduce the unicast packets converted by the packet duplicator to the forwarding unit again.

Abstract: Disclosed is a fast rerouting apparatus and method for multiprotocol label switching (MPLS) multicast. The fast rerouting apparatus and method is to rapidly cope with a failure occurring on an MPLS network. The fast rerouting method of redirecting a packet to be transmitted at the nearest location from a location where the failure occurs is applied to the MPLS multicast, so that it is possible to rapidly cope with the failure generated when an MPLS multicast packet is transmitted.

Abstract: This invention relates to a routing apparatus and to a routing method in a network system in which a 6to4 network is connected to a native IPv6 network. An optimum transmission route is selected by considering the topology of the 6to4 network and the topology of the native IPv6 network. One embodiment of the routing apparatus comprises an information collector, a message generator and a message transmitter. Another embodiment of the routing apparatus comprises a routing information collector, a message receiver, and a route selector. The network system comprises a 6to4 relay router and a 6to4 router. The method comprises collecting routing information of the native IPv6 network and the 6to4 network, respectively, and selecting the route based on the collected information. Finally, a message used for transmitting the routing information comprises a Border Gateway Protocol (BGP) update message.

Abstract: An Internet Protocol address look-up method for looking up an Internet Protocol address of an Internet Protocol packet in order to forward the Internet Protocol packet uses a ternary content addressable memory (CAM) which has routing entries, each including a pair of data strings having a prefix of an Internet Protocol address and a mask string representing a length of the prefix, which compares a search key as a destination address of the Internet Protocol packet to be forwarded with the routing entries, which sets a match line of a matching routing entry, and which outputs a mask string of the matching routing entry. The method comprises the steps of: comparing prefix lengths of mask strings outputted in correspondence to set match lines when at least one match line is set in the ternary content addressable memory (CAM); and determining, as a longest prefix matching (LPM) entry, a routing entry corresponding to a mask string having the longest prefix length.

Abstract: A network routing control method includes: setting best and secondary route information while receiving/transmitting a routing protocol control message with adjacent routers; setting a table having best and secondary next hop entries using the best and secondary route information; extracting a destination IP address from the best and secondary route information to set a forwarding table; and when a failure occurs in a network which is set as the best next hop entry according to the best route information, setting the secondary next hop entry as an output interface according to the secondary route information to forward a corresponding packet.

Abstract: In a tunneling method and apparatus for multicasting between an IPv4 network and an IPv6 network, a multicast table containing information about receive and transmit interfaces in a multicast delivery tree structure for each of the IPv4 network and the IPv6 network is set, a multicast address area is assigned to the first network and a multicast address area is assigned to the second network compatible with the first network, an IPv6 multicast packet containing source and multicast destination addresses of the IPv6 network is received, and when a destination network of the IPv6 multicast packet is the IPv6 network connected to the IPv4 network, source and multicast destination addresses of the IPv4 network are extracted from source and multicast destination addresses contained in the IPv6 multicast packet, the IPv6 multicast packet is capsulated into an IPv4 format, and the IPv4 format packet is multicast-tunneled to the IPv6 network through the IPv4 network by referring to the multicast table.