Abstract: An optical glass which contains at least 20 mol % of TeO2 and has an internal transmittance of at least 80% in a thickness of 2 mm to a light having a wavelength of 405 nm and a refractive index of at least 1.85 to the same light, and which contains no alkali metal oxide or contains alkali metal oxides in a total amount of at most 15 mol %.

Abstract: An objective lens capable of recording or reproducing informations of HD, DVD and CD is provided. A reference lens 2a and a close-contact lens 2b are closely in contact and bonded, the material of the close-contact lens 2b is different from the material of the reference lens 2a, a lens surface of the reference lens and a lens surface of the close-contact lens have aspherical shapes, the reference lens has a light-converging function, and the close-contact lens has a region providing a positive refractive power and a region providing a negative refractive power to construct an objective lens for optical information recording media.

Abstract: With respect to first to 11th DSL subscriber line termination units (112-1 to 112-11) each terminating subscriber lines for a plurality of channels on a board, there is provided an auxiliary DSL subscriber line termination unit (112-12) terminating the same number of subscriber lines on a board. Upon occurrence of failure corresponding to any of the channels, a redundant control panel (114) implements switching to a corresponding channel of the auxiliary DSL subscriber line termination unit. By this switching, a physical interface number of a packet is changed. However, it can be dealt with by conversion to the same logical interface number as before using a mapping table (212) under the control of a protection control section (215).

Abstract: Multicast communication frames for a plurality of channels corresponding to television programs and so on received from an uplink line 130 are subjected to limitation with respect to a total reception amount or limitation according to priorities and sent out from a first priority control section 192, then forwarded onto a backplane bus 128 as ATM cells from an ATM SAR 134. DSL subscriber line termination units 127 refer to their own local multicast distribution tables 211 obtained on the basis of a global multicast distribution table 205 to thereby duplicate as many copies of the ATM cells of the channels concerned as required and send them to corresponding DSL lines.

Abstract: In response to a request for acquisition of an IP address from a user terminal, a DHCP server 171B in a subscriber line accommodation device 102 allocates an IP address, registers a set of the allocated IP address, an MAC address of the user terminal, and a line number thereof in a DHCP management table 201, and sets it in an input filter section 184 as a packet passing condition. Among packets sent from user terminals, the input filter section 184 sends only those packets satisfying registered conditions toward a bridge forwarder 135, while discards those packets not satisfying the conditions. Even when access is attempted by illegally using an IP address, a packet concerned is discarded unless a line number or an MAC address agrees.

Abstract: An optical glass which contains at least 20 mol % of TeO2 and has an internal transmittance of at least 80% in a thickness of 2 mm to a light having a wavelength of 405 nm and a refractive index of at least 1.85 to the same light, and which contains no alkali metal oxide or contains alkali metal oxides in a total amount of at most 15 mol %.

Abstract: The object of the present invention is to accommodate physical segments of LANs into a switching hub substituting them for virtual LANs without modifying software of terminals or setting of the terminal and provide a routing function of the third layer without deteriorating the degree of freedom in virtual LAN setting of the switching hub. The internetworking router of the present invention includes LAN controlling means 1, packet memory 2, bridge processing means 3, table memory 4, routing processing means 5, table memory 6, free buffer queue 7, reception buffer queue 8 and transmission buffer queue 9 between LAN controlling means 1 and bridge processing means 3, and reception buffer queue 10 and transmission buffer queue 11 between bridge processing means 3 and routing processing means 5. Table memory 4 includes bridge group table 41 and address learning tables 42.sub.1 to 42.sub.n. Table memory 6 includes routing table 61 and ARP table 62.

Abstract: A router includes a routing table containing flags each representing a public-network side or a LAN side. A path for a received packet is determined such that the packet is forwarded to the next node through the LAN according to the next node address when the flag corresponding to the specified destination represents the LAN side, and the packet is forwarded to the next node through the public network according to the next node address when the flag represents the public network side. When a change of the routing information sets is monitored, the routing table is searched for the second router having the flag representing the public network side and then the changed routing information sets are transmitted to the second router.