Abstract: A communication system and a network relay device capable of improving failure tolerance are provided. For example, three port switches, fabric switches, and user switches are provided, and two of the port switches configure a multi-chassis link aggregation device. Each of the fabric switches detects the number of the port switches (for example, two switches) connected without failure while logically regarding the port switches configuring the multi-chassis link aggregation device as one switch, and transmits the number of the switches (two switches) from three ports. Each of the port switches sets a link aggregation group for two of the ports which have received the largest number of the switches (two switches).

Abstract: Each of the n port switches set LAG to m links which respectively connect the port switch and m fabric switches. For example, the port switch performs a hashing operation for a frame received at a predetermined port and containing a layer 4 port number of an OSI reference model by using the port number, determines one link based on a result of the hashing operation from among the m links to which the LAG is set, and relays the frame to the one link.

Abstract: A communication system includes a plurality of port switches that include first and second port switches, a plurality of fabric switches that construct communication paths among the plurality of port switches, and a user switch. Each of the plurality of port switches is connected to each of the plurality of fabric switches via different communication lines. The first and second port switches are connected by a common communication line between redundancy ports of the first and second port switches to thereby form a same domain group. The user switch is connected to each of the first and second port switches via different communication lines, and also sets link aggregation for ports of the user switch that are connection sources of the communication lines that connect the user switch and each of the first and second port switches.

Abstract: When a fabric switch detects a fault in its own link, the fabric switch transmits a first fault notification frame containing a fault link identifier representing the detected fault to a plurality of port switches. When the fabric switch receives a second fault notification frame from a plurality of port switches, it floods the second fault notification frame. When a port switch detects a fault in its own link, it transmits a second fault notification frame containing a fault link identifier to the plurality of fabric switches. Also, when the port switch receives the fault notification frame at all of its own links, it sets the LAG based on the fault link identifier.

Abstract: A port switch of type A has a distribution mode for maintaining a backward compatibility with a port switch of type B. A distribution identifier calculating unit performs a logical operation with the same operational expression to the same bit region as the type B in a header contained in a frame, thereby calculating a k-bit (k>j) distribution identifier partly containing the same j-bit bit region as the type B. A distribution table indicates a correspondence relation between three sub-links and the k-bit distribution identifier, and has contents in which the j-bit distribution identifier in the distribution table of the type B is replaced with the k-bit distribution identifier partly containing the same j-bit value as that of the j-bit distribution identifier.

Abstract: There is provided port switches SWP1 to SWP4, fabric switches SWF1 and SWF2, and user switches SWU1 and SWU2, the port switches SWP1, SWP2 functioning logically as one switch by being connected with a shared communication line between redundancy ports Pr. The port switch SWP2 may receive frames from the user switch SWU1, and when the frames are to be originally transferred from a port P1 to the fabric switch SWF1, the frames are transferred though the redundancy port Pr to the port switch SWP1 if there is a fault on the port P1 side. The port switch SWP1 transfers the frames received from the port switch SWP2 through the redundancy port Pr to the fabric switch SWF1 that is the original transfer destination.

Abstract: A network system has lower switches and upper switches connected to the lower switches. Each of the upper switches includes a connection information notifying means for notifying connected lower switch list informations each of which includes an identification information on each of the lower switches connected to each of the upper switches, to the lower switches connected to each of the upper switches. Each of the lower switches includes a comparison determination means for comparing the connected lower switch list informations notified by the connection information notifying means, in order to determine a connection state between the upper switches and the lower switches.

Abstract: A port switch includes ports that are to serve as communication sources of communication lines extending to a plurality of fabric switches, and sets a link aggregation for the ports. The port switch further includes a fabric switch table indicating a correspondence relationship between each of the addresses of the fabric switches and the corresponding one of the ports. When the port switch receives a frame from a terminal, the port switch detects a destination address in the frame, determines, if the destination address is one of the addresses in the fabric switch table, a port corresponding to the one of the addresses, on the basis of the fabric switch table to transfer the frame from the port.

Abstract: When a fabric switch detects a fault in its own link, the fabric switch transmits a first fault notification frame containing a fault link identifier representing the detected fault to a plurality of port switches. When the fabric switch receives a second fault notification frame from a plurality of port switches, it floods the second fault notification frame. When a port switch detects a fault in its own link, it transmits a second fault notification frame containing a fault link identifier to the plurality of fabric switches. Also, when the port switch receives the fault notification frame at all of its own links, it sets the LAG based on the fault link identifier.

Abstract: A network system includes a plurality of fabric switches and a plurality of port switches connected to the plurality of fabric switches through a plurality of links. A link aggregation group is set to the plurality of links connected to the plurality of fabric switches, and when the port switch receives a multicast management frame, it transfers the frame to each of the plurality of fabric switches. The fabric switch has a table in which information of a port which has received a frame and a source MAC address of a received frame are registered, and when the fabric switch receives the multicast management frame, it registers information of a port which has received the frame and a source MAC address of the frame in the table.

Abstract: A port switch of type A has a distribution mode for maintaining a backward compatibility with a port switch of type B. A distribution identifier calculating unit performs a logical operation with the same operational expression to the same bit region as the type B in a header contained in a frame, thereby calculating a k-bit (k>j) distribution identifier partly containing the same j-bit bit region as the type B. A distribution table indicates a correspondence relation between three sub-links and the k-bit distribution identifier, and has contents in which the j-bit distribution identifier in the distribution table of the type B is replaced with the k-bit distribution identifier partly containing the same j-bit value as that of the j-bit distribution identifier.

Abstract: Each of the n port switches set LAG to m links which respectively connect the port switch and m fabric switches. For example, the port switch performs a hashing operation for a frame received at a predetermined port and containing a layer 4 port number of an OSI reference model by using the port number, determines one link based on a result of the hashing operation from among the m links to which the LAG is set, and relays the frame to the one link.

Abstract: When a first switching device receives a control frame such as IGMP report at a MLAG port, it learns a multicast (MC) group contained in the control frame in association with the MLAG port on a MC address table. Also, the first switching device generates a bridge control frame containing the control frame and an identifier of the MLAG port and transfers it from a bridge port. On the other hand, when the second switching device receives the bridge control frame at the bridge port, it detects the control frame and the identifier of the MLAG port from the bridge control frame and learns the MC group contained in the control frame in association with its own MLAG port on the MC address table.

Abstract: A network system includes lower switches and upper switches connected to the lower switches. Each of the upper switches transmits a first notification frame containing a connected lower switch number information indicative of the number of the lower switches connected to each of the upper switches, to the lower switches connected to each of the upper switches. Each of the lower switches configures a link aggregation group for ports which received the first notification frames each of which contains a maximum value of the connected lower switch number information among the connected lower switch number informations contained in the received first notification frames.

Abstract: A network system includes a plurality of lower switching hubs, and upper switching hubs connected to each of the lower switching hubs, to relay a normal frame to be transmitted and received between the lower switching hubs. Each of the lower switching hubs includes a lower switch configuring portion for configuring a first link aggregation group for all ports connected to the upper switching hub, and transmitting a first control frame containing its own identifier from all the ports connected to the one or more upper switching hubs. Each of the upper switching hubs includes an upper switch configuring portion for configuring a second link aggregation group for ports connected to a same lower switching hub, based on the first control frames received from the lower switching hubs, and transmitting a second control frame containing its own identifier from the ports configured as the second link aggregation group.

Abstract: A communication system and a network relay device capable of improving failure tolerance are provided. For example, three port switches, fabric switches, and user switches are provided, and two of the port switches configure a multi-chassis link aggregation device. Each of the fabric switches detects the number of the port switches (for example, two switches) connected without failure while logically regarding the port switches configuring the multi-chassis link aggregation device as one switch, and transmits the number of the switches (two switches) from three ports. Each of the port switches sets a link aggregation group for two of the ports which have received the largest number of the switches (two switches).

Abstract: FSs (16a to 16h) are each connected to IFSs (14a to 14x). Each of the FSs (16a to 16h) transmits a setting frame (60) that includes an FS number to the connected IFSs (14a to 14x). Each of the IFSs (14a to 14x) registers, in an LAG setting table, the FS numbers included in the received setting frames (60) and ports that have received the same in association with each other. Then, each of the IFSs (14a to 14x) sorts ports (52a to 52h) in an order of the associated FS numbers, and sets each of LAGs (18a to 18x) in a common order.

Abstract: A port switch includes ports that are to serve as communication sources of communication lines extending to a plurality of fabric switches, and sets a link aggregation for the ports. The port switch further includes a fabric switch table indicating a correspondence relationship between each of the addresses of the fabric switches and the corresponding one of the ports. When the port switch receives a frame from a terminal, the port switch detects a destination address in the frame, determines, if the destination address is one of the addresses in the fabric switch table, a port corresponding to the one of the addresses, on the basis of the fabric switch table to transfer the frame from the port.

Abstract: A network relay system (10) includes a plurality of IFSs (14) and a plurality of FSs (16). The IFSs (14a to 14x) are each connected to the FSs (16a to 16h) through physical lines. In the IFSs (14), an LAG is set for ports connected to the FSs (16). The IFSs (14) and the FSs (16) transmit/receive a detection frame to/from each other, and when the detection frame fails to be received, it is determined that a failure has occurred within the network relay system (10). When one of the FSs (16) determines that a failure has occurred, the one of the FSs (16) transmits a failure notification frame to the plurality of IFSs (14), and each of the plurality of IFSs (14) excludes the port that has received the failure notification frame from the LAG.

Abstract: There is provided port switches SWP1 to SWP4, fabric switches SWF1 and SWF2, and user switches SWU1 and SWU2, the port switches SWP1, SWP2 functioning logically as one switch by being connected with a shared communication line between redundancy ports Pr. The port switch SWP2 may receive frames from the user switch SWU1, and when the frames are to be originally transferred from a port P1 to the fabric switch SWF1, the frames are transferred though the redundancy port Pr to the port switch SWP1 if there is a fault on the port P1 side. The port switch SWP1 transfers the frames received from the port switch SWP2 through the redundancy port Pr to the fabric switch SWF1 that is the original transfer destination.