Nec Corporation

Akira Arutaki

Atsushi Iwata

Kazuhiko Isoyama

Yuichi Ishikawa

Youichi Hidaka

Norihito Fujita

Motoo Nishihara

Yoshinori Yoshida

Nobuyuki Enomoto

Makoto Nishio

Masahiko Honda

Hiromi Takahashi

Tsuneo Nakata

Toshiya Aramaki

Yasuhiro Miyao

Kenshin Yamada

Hideo Yoshimi

Masao Hashimoto

Takafumi Sera

Suminori Yoshikawa

A VPN connection method and a communication system are provided, each which can omit the setting of a firewall and the installation of a relay server and can establish communications from the outside of a firewall to the inside thereof. The internal networkis connected to the external networkvia the firewall. The internal networkenables communications by an e-mail from the external network(outside the firewall) to the mail serverin the internal network(inside the firewall) or communications by telephone or radio, which is not via the firewall. The feature of the firewallis utilized that access from the outside to the inside of the firewall through VPN connection is very difficult but the access in the reverse stream can be simply performed. Using the mail server, telephone line or radio line, the internal networkreceives an e-mail, which requires for VPN connection from the external network, or control information through the telephone line. Thus, the internal networksends callback for VPN connection to the e-mail transmission source. As a result, the callback allows the external networkto pass through the firewall

Connection method, communication system, device, and program

A transmitter/receiveron a mobile bodyutilizes a plurality of antennas. It is assumed that a plurality of the antennasare distributed and arranged in a moving direction of the mobile body, and the antennas at both ends are away from each other at an extent that a distance between the antennas is not negligible as compared with an interval of the base station. A radio wave from the base station-is stronger in intensity in-than in the center, and the radio wave from the base station-is stronger in intensity in-than in the center, respectively, whereby the communication stabilization effect, which is larger as compared with the case that the antennas are locally located in the center, is expected. This enables the interval of the base station, which is broader than the conventional one, to be employed, yet both of a speed and a frequency of a hand-over process to be lowered, and in addition hereto, the bandwidth utilization efficiency, which is higher as compared with that of the conventional example, to be realized.

Mobile device and radio interface arrangement method

When a packet transfer equipment receives a packet, it extracts several types of information contained in the received packet such as the destination IP address and the destination port number and, using the extracted information as the key, inquires of a packet transfer method resolution server about the information related to the packet transfer method. The server keeps the correspondences between several types of information contained in the packet and one or more type of information related to the packet transfer method in the database and, in response to the inquiry from the packet transfer equipment, replies one or more type of information related to the packet transfer method. The packet transfer equipment rewrites several types of information such as the destination IP address and the destination port number according to one or more type of information obtained and transfers the received packet.

System and method for external resolution of packet transfer information

A method for transferring a series of layer-3 packets through an ATM network composed of a plurality of ATM switches is disclosed. An ingress gateway determines whether a packet flow has been registered and, when the flow has not been registered, determines a transfer route. A connection setup cell is transmitted to a next-hop ATM switch to ensure a connection dedicated to transfer of tho series of packets. Then, a series of packets is transferred to the next-hop ATM switch through the connection after the connection has been set up.

Layer 3 flow-switching method and system

A caching method for caching network contents of a packet transfer network including a packet relay for relaying accesses of clients to servers supplying contents, and a network contents cache device are disclosed. Accesses from the clients to the servers are monitored by the said packet relay to determine a cache priority on the basis of a product of relaying path lengths from the packet relay to the server and frequency of access from the client to the servers and the network contents cache device preferentially caches a response to the access to the server having higher cache priority.

Caching of network contents by packet relays that determine cache priority utilizing contents access frequency and metrics in their routing tables representing relaying path lengths

A communication quality control system for deciding an optimum communication quality in a received datagram to transfer the datagram, in which not only a destination is decided according to the data of the protocol layer and beneath included in the datagram, but also attribute information of communication is taken out by an attribute detecting unit, according to the information of the respective protocol layers , and or one of them, and communication quality for sending the datagram is decided by a communication quality deciding unit and a connection communication quality control unit, according to the quality information of connection corresponding to the attribute information taken out.

Communication quality control system

A fast reservation protocol type ATM switching method and ATM switching equipment which are capable to suppress deterioration in transmission efficiency by reducing a cell discarding rate even in case of transmitting a huge ATM cell burst is provided. A buffer monitoring circuit monitors the number of idle slots in a buffer of an ATM switching equipment. A resource management (RM) cell processing circuit compares the number of idle slots with the total number of cells consisting an ATM cell burst contained in an RM cell locating at the top of the ATM cell burst stream when receiving the ATM cell burst from an ATM subscriber equipment. If the number of idle slots is not available for storing all cells in the ATM cell burst, the RM cell processing circuit instructs a gate circuit to pass same number of cells as idle slots available in the buffer and discard the rest of cells, and transmits a RM cell, containing information of number of cells to be retransmitted, to the ATM subscriber equipment for requesting retransmission.

Method of asynchronous transfer mode (ATM) switching and an ATM

A network server includes LAN terminating units, an ATM terminating unit, a data transfer unit, a multiple identifier check section, and a connection determination section. The LAN terminating units are connected to LAN terminals constituting virtual LAN segments and terminate protocols on the LAN MAC sublayer. The ATM terminating unit is connected to an ATM network and terminates the AAL and the ATM protocol. The data transfer unit transfers received data to one of the LAN terminating units and the ATM terminating unit in correspondence with the destination MAC address obtained from data received by the LAN terminating units and the ATM terminating unit. The multiple identifier check section checks at least the Ethernet type in the SNAP of the received data. When the data is transferred from the data transfer unit to the ATM terminating unit, the connection determination section determines an ATM connection to which the data is to be transmitted, on the basis of a set of the destination MAC address and the destination IP subnetwork address, obtained from the received data, and an identifier including at least the Ethernet type detected by the multiple identifier check section, and notifies the ATM terminating unit of the determined ATM connection.

Network server

An ISDN remote switching unit for accommodating analogue telephone subscriber lines and ISDN digital subscriber lines comprises at least one signal converter for each of the conventional analogue subscriber so that a line signal, an address signal and tone signal of each conventional analogue subscriber are converted into a signaling system of the ISDN digital subscribers line, and a traffic concentrator connected to the signal converter and disposed remote from a host exchange station, whereby the signaling system between the remote station and the host station is unified for both the analogue telephone subscriber and the ISDN digital subscriber.

ISDN remote switching unit for accommodating analog and digital lines

For use in combination with an exchange which is coupled to a subscriber line used in transmitting a sequence of digital signals and comprises a time division switch unit coupled to the subscriber line and a control unit for controlling the time division switch unit to form an internal transmission path in the time division switch unit in response to the digital signals, a monitoring system comprises a command supply circuit for supplying a command to the control unit to form a monitoring path related to the internal transmission path in the time division switch unit. A coupling circuit couples to the subscriber line to a monitoring equipment through the monitoring path when the command is supplied from the command supply circuit to the control unit. The digital signal sequence is monitored by the monitoring equipment.

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Tokyo, Japan

Akira Arutaki