Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Other

Tetsuro Yoshimoto

Akihiko Takase

Kazuho Miki

Masahiro Takatori

Koji Wakayama

Masaru Murakami

Masao Kunimoto

Masatoshi Takihiro

Satoshi Shimizu

Yukiko Takeda

Hidenori Inouchi

Shiro Tanabe

Eri Kawai

Masanori Kamata

Mariko Yamada

Kengo Ijima

Masaki Nara

When an IPv4/v6 dual stack terminal communicating via TCP on IPv6 fails to promptly switch over to IPv4 after the ICMPv6 fails due to a soft error, the problem should be resolved at the prior stage server rather than on the complicated terminal. The server at a stage prior to the terminal receives TCP packets from the terminal to find the TCP connection status on the terminal. When the terminal connection status is SYN-SENT or SYN-RECEIVED, and the server receives an unaddressed soft error such as ICMPv6 'Destination Unreachable: no route to destination (ICMP type=1: code 0)' for that terminal, the server rewrites the ICMPv6 contents as a hard error such as 'Destination Unreachable: communication with destination administratively prohibited (ICMP type=1: code 1)' and sends it the terminal.

ICMP translator

An object of the present invention is to solve a problem that when multicast is utilized in a network configured with virtual routers, traffic in the relay network is increased. According to the present invention, the number of multicast packets via the relay network is reduced by performing a multicast packet transfer across the virtual routers within the same router. Specifically, it is allowed to register in a multicast routing table held by each virtual router, a line interface identifier of another virtual router as outgoing line interface information, whereby multicast packet transfer from a virtual router to another virtual router is made possible. In order to specify a virtual router to share the multicast packet, each virtual router holds information to specify a virtual router having a line interface to receive the multicast traffic indicated by the multicast group address.

Multicast packet relay device adapted for virtual router

Even when session control traffic such as SIP traffic to be unitarily subjected to QoS management by a manager of a session control network such as an SIP network, and loopback traffic to be freely subjected to QoS management by users coexist, QoS processing can be appropriately performed. The edge router checks a routing table and the address information of an SIP message to derive an SIP stream direction. The edge router timely selects a table that can be set by only SIP network managers, and a table that can be set by user network managers as well, determines QoS setting information by collating other SIP/SDP message information, and sets it in a QoS function unit.

Router

L2TP packet forwarding apparatus to be connected to at least two LACs (L2TP Access Concentrators) via L2TP sessions to receive packets transmitted from a gateway, which accommodates user terminals, in the form of a L2TP packet encapsulated in Bridge over PPP, has a lookup table indicating the correspondence of tunnel ID/session ID pairs to an identifier (VPN-IDs) of a wide area network to which a plurality of user terminals belong. The packet forwarding apparatus specifies an VPN-ID from the lookup table based on the tunnel ID and the session ID of a received packet and forwards, if it is confirmed that another tunnel ID/session ID pair associated with the same VPN-ID exists in the lookup table, the received packet to another L2TP session identified by the another tunnel ID/session ID pair in the form of a L2TP packet.

Packet forwarding apparatus and communication network suitable for wide area Ethernet service

The present invention relates to a domain name solution method in dynamic DNS and a device for domain name solution. A dynamic DNS server includes an address translation means which assigns a host a virtual address corresponding to an actual address of the host. The dynamic DNS registration method comprises a step in which the address translation means assigns a virtual address to the host upon a registration request issued from the host and a step of storing a tuple of the actual address, virtual address, and domain name of the host, which are associated with each other.

Dynamic DNS registration method, domain name solution method, DNS proxy server, and address translation device

A packet transfer apparatus connected to an internal subnetwork formed by a set of broadcast segments each accommodating terminals and for transferring, when a MAC frame including a IP address which designates a destination terminal connected to one of the segments is received from a terminal connected to another segment in the internal subnetwork, an IP packet in the MAC frame to the segment connected to the destination terminal in accordance with a terminal management table which indicates a relation of address information of each of the terminals belonging to the internal subnetwork and the segment to which the terminal is connected.

Packet transfer apparatus connectable with mobile terminals

A method of providing web accessing service and a server apparatus for carrying out the method, wherein access from a user in a LAN to a search engine is monitored, and keyword information is stored. Then, based on the keyword information, the access to the search engine is made again by a web site storage server, and resulting contents of web sites are all stored in the web site storage server.

Web system using proxy server monitoring server and storage server for efficiently providing web access service to users within passenger transportation environment

In a system in which communication is performed among a plurality of devices having a mechanism of disassembling a packet into ATM cells to send them and a plurality of devices having a mechanism of assembling the received ATM cells into the packet, a frame is prevented from being lost owing to change of virtual connections in the course of transferring the frame, improving reliability of the communication on the packet level. When the switch receives a request for change of switching, it does not processes that request at once, but confirms that the cell located at the boundary of the frame has been processed, before processing the change request, so as to protect the frame. When the switch receives a request for change of switching, it protects a frame by multicasting the cells to both destinations before change and after change, for a given period of time.

IP switch, interface circuit and ATM switch used for IP switch, and IP switch network system

A router apparatusis provided with an ATM switch, an IP controller for performing routing control as a controller for layer, plural kinds of interfaces which are individually provided to plural transmission paths in which various communications are performed, and a cell multiplexing/demultiplexing unit, and manages the cell communications between respective parts on the basis of identification information. The input packet is subjected to IP processing in an interface to be converted to a cell in a common format, and the cell is serially multiplexed with a cell from another interface on a cell basis, and transmitted to the ATM switch at the cell multiplexing/demultiplexing unit. Each interface and each cell multiplexing/demultiplexing unit sets and switches the identification information for the header portion of the packet and the cell to be communicated by using a table in which the corresponding relationship of the identification information is registered.

Router apparatus using ATM switch

A server for controlling a gateway connecting a transport layer and an IP network has the function of accessing a service control point (SCP) via a service control gateway . A server for controlling terminals on the IP network stores information of correspondence between telephone number of a terminal and the IP address. When a signal including number information which requires an access to the SCP is received from a terminal managed by the server , an interrogation request is multicasted to the other servers each having the function of accessing the SCP. A server which has sent a response signal accesses the SCP via the service control gateway to provide an IN service process.

Communication method for terminals connected to IP networks to receive services provided by intelligent networks

A router apparatus is provided with an ATM switch, an IP controller for performing routing control as a controller for layer , plural kinds of interfaces which are individually provided to plural transmission paths in which various communications are performed, and a cell multiplexing/demultiplexing unit, and manages the cell communications between respective parts on the basis of identification information. The input packet is subjected to IP processing in an interface to be converted to a cell in a common format, and the cell is serially multiplexed with a cell from another interface on a cell basis, and transmitted to the ATM switch at the cell multiplexing/demultiplexing unit. Each interface and each cell multiplexing/demultiplexing unit sets and switches the identification information for the header portion of the packet and the cell to be communicated by using a table in which the corresponding relationship of the identification information is registered.

An LAN interface unit and an ATM switch unit cooperate to perform traffic control. A QoS unit monitors circumstances of an input buffer from a multiplexer of the ATM switch by means of a system controller and when an overflow of the input buffer is expected, the LAN interface unit of the multiplexer is instructed to perform traffic control. The LAN interface unit performs traffic control such as limitation of ATM cells inputted in the ATM switch.

A router apparatus 5 is provided with an ATM switch, an IP controller for performing routing control as a controller for layer 3, plural kinds of interfaces which are individually provided to plural transmission paths in which various communications are performed, and a cell multiplexing/demultiplexing unit, and manages the cell communications between respective parts on the basis of identification information. The input packet is subjected to IP processing in an interface to be converted to a cell in a common format, and the cell is serially multiplexed with a cell from another interface on a cell basis, and transmitted to the ATM switch at the cell multiplexing/demultiplexing unit. Each interface and each cell multiplexing/demultiplexing unit sets and switches the identification information for the header portion of the packet and the cell to be communicated by using a table in which the corresponding relationship of the identification information is registered.

Growing community of inventors

Kokubunji, Japan

Tetsuro Yoshimoto