Fault recovery method for handover and ring network using ring network retrieving drop connection destination of packet from ring network with low-order address of destination mac address of ethernet frame

Abstract

To implement a ring transmission line fault recovery of a handover of a radio system at low cost and at high speed.SOLUTION: In the case of a fault of a ring network, a packet for a counterclockwise ring transmission line of a device for adding, dropping and passing a packet in contact with a fault point is looped back to an input buffer at a reception side of a clockwise ring. In a case where a packet of which a destination MAC address is a NICMAC address of a ring network interface of a router 22 arrives at the device from the reception side of the clockwise ring, the destination MAC address is stored in a ring transmission line port address table in front of the clockwise ring or the device is brought into a steering state. In a case where a lower-order address of a transmission source MAC address is stored in a lower-order address memory designating a packet transmission to the outside of the ring, the lower-order address is deleted, the lower-order address of the transmission source MAC address is stored in a double use lower-order address memory, and the packet is transmitted to the front side of the clockwise ring.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a network handover and ring fault recovery method that utilizes the characteristics of a ring network, in which an Ethernet frame or IEEE802.3 MAC packet is transferred in the section from the base station of a mobile network to a router across a ring network, and a lower address memory that stores the lower address of a MAC address is used as a device for adding, dropping and passing packets of the ring network, and searches for a drop connection destination from the ring network using the lower address of the destination MAC address of an Ethernet frame or IEEE802.3 MAC packet. In this invention, a packet is used in which the MAC address part of the IPv6 address is used as the MAC address of the Ethernet frame or IEEE802.3 MAC packet.

[0002] A conventional example of an address storage method is disclosed in Japanese Patent Application Laid-Open No. 2000-151617, "Table This conventional example is related to the storage circuit of MAC addresses, It consists of a first table consisting of a RAM or the like having a column address, a MAC address data area, and an index area, and a second table consisting of a RAM or the like having a row and column address, a MAC address data area, and an index area. In this conventional example, the entire 48 bits of a MAC address are stored at position A, which is specified in the memory of the first table by the lower bit string (for example, 16 bits). If another MAC address is already stored at position A, it is recorded at an empty address position B in the memory of the second table, and the recorded address position B is stored in the index area of ​​address position A of the first table. This is a method of specifying a recording area by nesting.

[0003] As a conventional technique for storing addresses, Patent Document 2, Japanese Patent Application Laid-Open No. 2004-15592, "MAC address pointer structure, MAC address rearrangement method." This conventional example is a method of storing multiple MAC addresses at the same address position in an entry table specified by a low-order bit string. If there is no free area, the MAC address is stored in an entry table specified by a low-order bit string different from the low-order bit string of the MAC address.

[0004] A typical conventional example of a ring network is a ring network using a master switch and a slave switch, as described in Patent Document 3. If one of the ring ports on the switch is a blocked port that does not pass frames, This prevents congestion caused by cluttering. If a fault occurs in the ring network, the monitoring frames sent from the master switch to the master switch will not arrive, and instead The master switch receives a failure notification frame from the slave switch at the failure point. The master switch unblocks the blocked port of the master switch to allow the frame to pass. Also, a blocked port is set on the failed transmission line side of one of the slave switches of the failure point, and the link The ring network continues to operate even after the ring network has recovered from a failure. Generally, in a conventional ring network, a MAC address table is used in the ring node device, so that in the event of a transmission line failure, the FDBs of all ring node devices in the ring are cleared and the FDBs are reconstructed by flooding.

[0005] An example of a handover method is Patent Document 4. This prior art is a method that has an IPv6 connection via a base station before switching via a gateway and a base station between a mobile terminal and an access router, and an IPv6 connection via a destination base station, and reduces the interruption time of packets via the connections when switching connections. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2000-151617 A [Patent Document 2] JP 2004-15592 A [Patent Document 3] Retable No. 2008-068813 [Patent Document 4] Re-tabled publication No. 2017-195497 [Non-patent literature]

[0007] [Non-Patent Document 1] G.8032 “Ethernet Ring Protection Swithing” Summary of the Invention [Problem to be solved by the invention]

[0008] The conventional address storage method disclosed in Japanese Patent Application Laid-Open No. 2000-151617 stores MAC addresses by nesting, which causes a problem that it takes a long time to trace the stored address destination.

[0009] In addition, in the conventional address storage method disclosed in Japanese Patent Application Laid-Open No. 2004-15592, the lower bits It is described that if there is no vacancy in the entry table position of the MAC address specified by the string, the MAC address will be stored in the entry table position of a different lower bit string. In that case, however, when selecting the position to store the MAC address, it is necessary to search the entry table positions specified by the two lower bit strings, and since there are multiple stored addresses at the same address position in the same entry table, it is necessary to compare these multiple addresses, which results in a problem of long search times.

[0010] Conventional ring networks, such as Non-Patent Document 1 and Patent Document 3, store the destination MAC addresses of packets bound for the left-handed ring, the destination MAC addresses of packets bound for the right-handed ring, and the destination MAC addresses of packets sent outside the ring using MAC addresses and port numbers, which results in a large number of MAC addresses to be stored.When the MAC address table stores the entire 48 bits of the MAC address at the address position accessed by the memory using the lower address of the MAC address, or when the upper address is stored, if the MAC address cannot be stored, a drawback is that when the destination MAC address of a packet to be forwarded is not stored in the MAC address table, the packet is flooded.

[0011] In addition, because an FDB (Forwarding Database) based on a MAC address table is used, when a loopback packet returns to the source ring node device in the event of a ring transmission path failure, the source MAC address of the packet has the port number stored as the port number outside the ring, so in RPR, the port number of the destination MAC address of the packet is set to the ring downstream transmission path port, making it possible to transition to steering; however, in a normal Ethernet ring, the arrival ring port and source MAC address are stored as a pair in the MAC address table, so there is a problem that it is not possible to transition to steering operation. In addition, a blocking point is adopted in the ring as an STP to avoid congestion caused by flooding when recovering from a fault in the ring network. However, because of this blocking point, a method of transitioning from wrapping to steering, such as RPR, cannot be used, and it becomes necessary to re-store the FDB by flooding.

[0012] Furthermore, in a conventional ring network, when searching for a connection destination, the entire destination MAC address is required, and searching using the lower address of the destination MAC address is not possible. Also, in a ring network, even if it is desired to store the source MAC address of a packet in an address table that specifies the passage of the packet so that a reverse packet can pass through a node device that stores a lower address equal to the lower address of the source MAC address, the storage process is not possible because the lower address of the destination MAC address does not indicate when the packet arrived at the destination. When the destination address is fixed, such as a server, it can be reached using the destination MAC address, but this is not possible for a terminal with many destinations.

[0013] Furthermore, the conventional handover technique disclosed in Patent Document 4 provides two IP6 connections between an access router and a mobile terminal for switching, which requires identification of the two IPv6 connections, resulting in a drawback in that handover control becomes complicated.

[0014] In conventional wireless networks, incoming packets were distributed to all base stations in the entire destination area, and a call signal to the destination terminal was sent to the wireless section only if the destination terminal's MAC address or telephone number was stored in the base station's MAC address table.As a result, packets with incompatible destinations had to be discarded, resulting in a large amount of power consumption.

[0015] The object of the present invention is to provide a method for recovering from a ring fault in a ring network in which a lower address memory that stores lower addresses of a MAC address is used in a ring node device, thereby realizing a simple handover without using a conventional MAC address table. [Means for solving the problem]

[0016] The present invention has been made in consideration of the above-mentioned problems of the prior art, and the means for solving the problems are as follows: These are the first to tenth aspects of the present invention. A first aspect of the present invention is a system in which a plurality of devices for adding, dropping and passing packets are inserted into a ring network of an optical transmission path 2 for a clockwise ring and an optical transmission path 1 for a counterclockwise ring, a base station is connected to the devices for adding, dropping and passing packets, and a mobile terminal under the base station has a function of receiving a packet arriving from the counterclockwise ring of the ring network or from the clockwise ring when a fault occurs in the ring network, and transferring the packet to a router, and a function of blocking the passage of a packet having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packet is stored in a MAC address table of the device itself, the system being configured to transmit data between the mobile terminal and the router across the ring network as an Ethernet frame of TCP or UDP for a call signal or the like, and between the router and the server or the switch as an IP packet, in order to communicate with a destination server via the router connected to the router for a video lecture, a video conference involving a call signal, or content distribution, or to provide a call service with a switch via the router, In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, Regardless of whether the packet is a packet immediately after the mobile terminal changes the destination base station or immediately after the change, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory specifying packet transmission outside the ring; otherwise, the packet is sent out counterclockwise to the front of the ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a means for, when a lower address of the source MAC address of the packet is stored in a lower address memory 7 that designates packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that designates packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise transferring the packet directly forward to a router 22 connected to a server 20 via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, means for, when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of a destination MAC address of the packet is stored in a duplicated use lower address memory, copying the packet and sending the copied packet forward in a clockwise direction and sending the original packet of the copied packet out of the ring, if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory specifying packet transmission out of the ring, sending the packet out of the ring, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory specifying packet transmission out of the ring, sending the packet forward in a clockwise direction; The mobile terminal sends a location registration packet having the MAC address of the mobile terminal to the exchange via the ring network, or sends a mail reception access packet to the mail reception server, and when the packet arrives at a packet add, drop and pass device from outside the ring, if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet specifies packet transmission outside the ring, and if the location registration packet arrives at a device for adding, dropping and passing a packet, or if the mail reception access packet arrives at a device for adding, dropping and passing a packet, and the lower address of the source MAC address of the packet is stored in lower address memory 7 that specifies packet sending out of the ring, the lower address of the source MAC address of the packet is erased from lower address memory 7 that specifies packet sending out of the ring and the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and otherwise the packet is forwarded via an optical transmission path to router 22 to which server 20 is connected.

[0017] A second aspect of the present invention is a system according to the first aspect of the present invention, characterized in that the device for adding, dropping and passing packets comprises means for storing two bits when storing a lower address in the duplicated use lower address memory when storing a lower address in the lower address memory specifying packet transmission outside the ring and storing the lower address in the duplicated use lower address memory simultaneously, erasing the two bits one bit at a time at a constant period, and erasing the lower address from the duplicated use lower address memory when the second bit is erased and the lower address is stored in the lower address memory specifying packet transmission outside the ring.

[0018] A third aspect of the present invention provides a system according to the first aspect of the present invention, The system is characterized in that the overlapping use lower address memory is configured to store the upper part of the lower MAC address excluding the lower part at an address position of a memory accessed by the lower part of the lower MAC address.

[0019] A fourth aspect of the present invention provides a system according to the second aspect of the present invention, The duplicated use lower address memory is configured to store the upper part of the lower MAC address excluding the lower part at an address location of a memory accessed by the lower part of the lower MAC address, and the two bits stored at the lower address storage location are stored at the rear of the upper part.

[0020] A fifth aspect of the present invention provides a system according to the first aspect of the present invention, This system is characterized in that when a lower address is stored in a lower address memory that specifies packet sending outside the ring of the device for adding, dropping, and passing the packet, and when the lower address is stored in a duplicated use lower address memory, if the lower address of the MAC address is stored in the lower address memory that specifies packet sending outside the ring after a certain time from that point, the lower address is erased from the duplicated use lower address memory.

[0021] A sixth aspect of the present invention provides a system according to the first aspect of the present invention, In the packet add, drop and pass device, 8-bit parallel data of a packet arriving from a clockwise ring and 10 bits of the first bit of a frame and the last bit of a frame are input to an input FIFO, and when the first bit of the frame is read from the FIFO by a sequencer circuit, a 550-byte timer and a 1500-byte timer are started to operate, and if the last bit of the frame is read before the 550-byte timer times out, reading from the FIFO is stopped, and the 1500-byte timer is reset by a timeout pulse of the 550-byte timer, and and means for resetting all JKFFs of the sequencer circuit and resuming reading of the FIFO regardless of the end of the sequence of the path, while stopping operation of the 550 byte timer if the end bit of the frame is not read before the 550 byte timer times out, and stopping reading from the FIFO if the end bit of the frame is read before the 1500 byte timer times out, and resetting all JKFFs of the sequencer circuit and resuming reading of the FIFO regardless of the end of the sequence of the sequencer circuit.

[0022] A seventh aspect of the present invention provides a system according to the first aspect of the present invention, comprising: In the event of a ring network failure, a means for looping back packets at add, drop and pass devices on both sides of the failure point, adding a loopback bit when the packets are looped back, allowing the packets to pass through all devices up to the second loopback point, and removing the loopback bit at the second loopback; or A packet on the left-handed ring transmission line of a packet add, drop and pass device adjacent to the failure point is looped back to an input buffer on the receiving side of the right-handed ring, and when a packet whose destination MAC address is the NIC MAC address of the ring network interface of the router 22 arrives from the receiving side of the right-handed ring to the packet add, drop and pass device, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; when the packet arrives at the add, drop and pass device of the packet, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; On the other hand, when a packet from a base station outside the ring arrives at a device for adding, dropping, or passing the packet, if the destination MAC address of the packet is stored in the ring transmission line port address table, or if the device for adding, dropping, or passing the packet is in a steering state, a steering bit is added to the packet, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in lower address memory 7 that specifies packet transmission outside the ring, and store the lower address of the source MAC address of the packet in the duplicated use lower address memory, and send the packet forward on the clockwise ring; On the other hand, if the packet is not a packet immediately after the mobile terminal changes the destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in a lower address memory that specifies packet transmission outside the ring, and transmit the packet to the front of the ring in a clockwise direction; When the packet arrives at a packet add, drop, and pass-through device from the clockwise ring, if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, the lower address of the lower address memory is erased, the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and the packet is sent to the front of the clockwise ring; When the packet arrives at a vertex device from the clockwise ring, store the lower address of the source MAC address of the packet in a lower address memory, and forward the packet to a server or switch via the router 22; When a packet from a server or an exchange arrives at a vertex device via a router 22, if the lower address of the destination MAC address of the packet is stored in the lower address memory, the packet is transferred on the counterclockwise ring with a steering bit added, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory, the packet is transferred on the clockwise ring without a steering bit added. The system further comprises:

[0023] An eighth aspect of the present invention is a method for transmitting packets as TCP or UDP Ethernet frames between the mobile terminal and the router across the ring network, and as IP packets between the router and the server or the switch, in order to communicate with a destination server via the router for television lectures, television conferences involving telephone calls, and content distribution, or to provide telephone service with a switch via the router, the method comprising: inserting a plurality of packet add, drop and pass devices in a ring network of an optical transmission path 2 for a clockwise ring and an optical transmission path 1 for a counterclockwise ring; connecting a base station to the packet add, drop and pass devices; and having a function for a mobile terminal under the base station to receive packets arriving from the counterclockwise ring of the ring network, or from the clockwise ring when a fault occurs in the ring network, and to forward the packets to a router, and to block the passage of packets having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packets is stored in a MAC address table of the device itself, the method comprising the steps of: In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, Regardless of whether the packet is a packet immediately after the mobile terminal changes the destination base station or immediately after the change, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory specifying packet transmission outside the ring; otherwise, the packet is sent out counterclockwise to the front of the ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a step of, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 that specifies packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that specifies packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise forwarding the packet as it is to a router 22 to which a server 20 is connected via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, a step of copying the packet and sending the copy packet forward in the clockwise direction when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of the destination MAC address of the packet is stored in a duplicated use lower address memory, sending the copy packet out of the ring, if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring, sending the packet out of the ring, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring, sending the packet forward in the clockwise direction when A location registration packet having a MAC address of a mobile terminal is sent to an exchange via a ring network, or a mail reception access packet of the mobile terminal is sent to a mail reception server, and when the packet arrives at a packet add, drop and pass device from outside the ring, if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and when the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet arrives at a device for adding, dropping and passing packets from outside the ring, and if the lower address of the source MAC address of the packet is stored in a lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in a lower address memory specifying packet transmission outside the ring, and otherwise the packet is sent forward counterclockwise on the ring as is; and when the location registration packet or the mail reception access packet arrives at a packet add, drop or pass-through device, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is erased from the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and otherwise the packet is forwarded via an optical transmission path to router 22 to which server 20 is connected.

[0024] A ninth aspect of the present invention is a method for transmitting packets as Ethernet frames of TCP or UDP such as speech signals between a mobile terminal and the router across the ring network, and as IP packets between the router and the server or the switch, the method comprising: inserting a plurality of devices for adding, dropping and passing packets into a ring network of an optical transmission path 2 for a clockwise ring and an optical transmission path 1 for a counterclockwise ring; connecting a base station to the devices for adding, dropping and passing packets; and having a function for a mobile terminal under the base station to receive a packet arriving from the counterclockwise ring of the ring network, or from the clockwise ring when a fault occurs in the ring network, and to forward the packet to a router, and to block the passage of a packet having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packet is stored in a MAC address table of the device itself, the method comprising the steps of: In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 that specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring, If the packet is not a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a step of, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 that specifies packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that specifies packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise forwarding the packet as it is to a router 22 to which a server 20 is connected via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, a step of copying the packet and sending the copy packet forward in the clockwise direction when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of the destination MAC address of the packet is stored in a duplicated use lower address memory, sending the copy packet out of the ring, if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring, sending the packet out of the ring, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring, sending the packet forward in the clockwise direction when When a location registration packet having the MAC address of a mobile terminal is sent to a switchboard via a ring network, or when a mail reception access packet of the mobile terminal is sent to a mail reception server, and the packet arrives at a packet add, drop, and pass-through device from outside the ring, and the packet is a packet immediately after the mobile terminal has changed its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 that specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring, If the packet is not a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring; When the location registration packet or the mail reception access packet arrives at a device for adding, dropping and passing packets, if the lower address of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, the lower address of the source MAC address of the packet is erased from lower address memory 7 which specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in duplicated use lower address memory, and otherwise the packet is directly forwarded via an optical transmission path to router 22 to which server 20 is connected.

[0025] A tenth aspect of the present invention relates to a method according to either the eighth or ninth aspect of the present invention, comprising: In the event of a ring network failure, A step of looping back the packet at the add, drop and pass devices on both sides of the failure point, adding a loopback bit when the packet is looped back, passing the packet with the loopback bit through all the devices up to the point where the packet is looped back a second time, and removing the loopback bit at the second loopback; or A packet on the left-handed ring transmission line of a packet add, drop and pass device adjacent to the failure point is looped back to an input buffer on the receiving side of the right-handed ring, and when a packet whose destination MAC address is the NIC MAC address of the ring network interface of the router 22 arrives from the receiving side of the right-handed ring to the packet add, drop and pass device, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; when the packet arrives at the add, drop and pass device of the packet, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; On the other hand, when a packet from a base station outside the ring arrives at a device for adding, dropping, or passing the packet, if the destination MAC address of the packet is stored in the ring transmission line port address table, or if the device for adding, dropping, or passing the packet is in a steering state, a steering bit is added to the packet, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in lower address memory 7 that specifies packet transmission outside the ring, and store the lower address of the source MAC address of the packet in the duplicated use lower address memory, and send the packet forward on the clockwise ring; On the other hand, if the packet is not a packet immediately after the mobile terminal changes the destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in a lower address memory that specifies packet transmission outside the ring, and transmit the packet to the front of the ring in a clockwise direction; When the packet arrives at a packet add, drop, and pass-through device from the clockwise ring, if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, the lower address of the lower address memory is erased, the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and the packet is sent to the front of the clockwise ring; When the packet arrives at a vertex device from the clockwise ring, store the lower address of the source MAC address of the packet in a lower address memory, and forward the packet to a server or switch via the router 22; When a packet from a server or an exchange arrives at a vertex device via a router 22, if the lower address of the destination MAC address of the packet is stored in the lower address memory, the packet is forwarded on the counterclockwise ring with a steering bit added, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory, the packet is forwarded on the clockwise ring without a steering bit added. The method further comprises: Effect of the Invention

[0026] As described above, in the present invention, even if a lower address memory is used for the device for adding, dropping and passing packets, which is a ring node device, when an incoming packet from a switch arrives at a ring node device from a clockwise ring, the device for adding, dropping and passing packets can operate in the same manner as a packet that is not a communication start packet, so that the device can receive the packet without increasing the hardware scale of the ring network and without increasing the power consumption of the base station. In addition, since flooding is not required even when a ring transmission path fault occurs, congestion does not occur even if the Ethernet domain is large. In addition, congestion is unlikely to occur because a transition from loopback recovery to steering mode can be made immediately when a ring transmission path fault occurs. In addition, the present invention operates the device for adding, dropping and passing packets with a sequencer, so that operation is simple and fast, and uses a lower MAC address memory instead of a conventional MAC address table, so that system costs can be reduced. In addition, the present invention is a method for realizing handover of a mobile terminal within a MAC1 domain by a ring network using the above memory, so that power consumption and system costs can be reduced and communication can be performed at high speed. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram for explaining an example of handover operation in a packet forwarding system between a terminal that forwards MAC packets through a base station connected to the packet add, drop and pass device having a lower address memory that specifies packet transmission outside the ring, a duplicated use lower address memory, and a ring transmission line port address table in a dual ring network in which multiple rings are connected by an optical ring, and a server or exchange connected to the ring network via a router. [Diagram 2] FIG. 2 is a diagram for explaining an example of a ring transmission line failure recovery operation of a handover in a packet forwarding system between a terminal that forwards MAC packets through a base station connected to the packet add, drop and pass device having a lower address memory that specifies packet transmission outside the ring, a duplicated use lower address memory, and a ring transmission line port address table in a dual ring network in which multiple devices are connected by an optical ring, and a server or exchange connected to the ring network via a router. [Figure 3A] FIG. 1 is a diagram showing the operation flow of a device for adding, dropping, and passing packets in a first embodiment of the present invention. [Figure 3B] FIG. 1 is a diagram showing the operation flow of a device for adding, dropping, and passing packets in a first embodiment of the present invention. [Figure 3C] FIG. 1 is a diagram showing the operation flow of a device for adding, dropping, and passing packets in a first embodiment of the present invention. [Figure 4] FIG. 1 shows a sequencer circuit of a packet adding, dropping and passing device according to a first embodiment of the present invention. [Diagram 5] FIG. 2 shows a sequencer driving circuit of a packet adding, dropping and passing device according to a second embodiment of the present invention. [Figure 6]FIG. 2 shows a sequencer driving circuit of a device for adding, dropping and passing packets when looping back on both sides of a fault point without switching to steering when a ring network fault occurs in a second embodiment of the present invention. [Figure 7] FIG. 1 shows the principle of storing lower addresses in a lower address memory that specifies packet transmission outside a ring, which is used in the packet adding, dropping and passing devices of the first and second embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] A first embodiment of the present invention will be described with reference to Fig. 1. This embodiment is an example of handover operation in which a mobile terminal accommodated in a base station connected to a packet add, drop and pass device of a double ring network, which is formed by connecting a lower address memory specifying packet transmission outside the ring, a duplicated use lower address memory, an address table specifying packet transmission outside the ring, and a ring transmission line port address table, transfers information as a MAC packet to a router connected to the ring network, and a mobile terminal can receive TCP packets and UDP one-way packets by using the ring network in a packet forwarding system between a server or a switch connected to the ring network via the router. The server is an Internet connection server or a content server. From the NIC of the ring network interface of the router 22 through the ring network to the NIC of the wireless interface of the base station is one MAC domain. The content server may be a cloud center. In Fig. 1, 1 is an optical transmission line of a counterclockwise ring, 2 is an optical transmission line of a clockwise ring, 5 is a vertex device, 6-1, 6-2, and 6-3 are devices for adding, dropping, and passing packets, 7 is a lower address memory that specifies packet transmission outside the ring, 9 is a ring transmission line port address table, 12 is a duplicated use lower address memory, 13-1, 13-2, and 13-3 are TCP mobile terminals or UDP mobile terminals, 14-1, 14-2, and 14-3 are base stations, 20 is a content server or a service provider's Internet connection server, 22 is a router, and 23 is a switch. In addition, (1) to (31) indicate the transfer order of packets in which the MAC addresses transferred on the ring indicated by the dotted lead line are abbreviated by letter symbols, and I0, I1, I2, I3, I4, and I7 are global IPv4 addresses that are dynamically set as IP addresses in the terminals, or domestic IPv4 addresses of the service provider. Or they are IPv6 addresses. The OE conversion circuit, EO conversion circuit, input buffer, and output buffer are not shown in the figure.

[0029] The operation of Fig. 1 will be explained below. An example is shown in which UDP mobile terminal 13-2 in a call sends packet (1) Mn1a3a2 (I7) (M indicates an Ethernet packet, n1 indicates the wireless MAC address of the interface of base station 14-1, a3a2 indicates the upper MAC address a3 and the lower MAC address a2 which are the MAC addresses of UDP terminal 13-2, and I7 indicates the IP address of the destination exchange 23) to base station 14-1. Base station 14-1 sends (2) Mr1r2a3a2 (I7) (r1r2 indicates the NICMAC address of the ring network interface of router 22) to packet add, drop and pass device 6-2 as an Ethernet packet via wired line.When the packet from the UDP mobile terminal 13-2 reaches the add, drop and pass-through device 6-1, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 which specifies packet transmission outside the ring, and the packet is sent towards the vertex device 5 via the working optical transmission line 1 of the counterclockwise ring. When the packet arrives at the add, drop and pass-through device 6-2 as shown in the figure by (3) Mr1 r2 a3 a2 (I7), the lower address a2 of the source MAC address of the packet is not stored in the lower address memory 7 which specifies packet transmission outside the ring. Therefore, the packet is transferred as it is through the counterclockwise ring 1 and arrives at the add, drop and pass-through device 6-3 as (4) Mr1 r2 a3 a2 (I7). Since the destination MAC address r1r2 of the packet is not stored in the memory 7, the packet is transferred as is through the counterclockwise ring 1, and when it arrives at the vertex device 5, the name of the counterclockwise ring 1 through which the packet has been transferred is stored in the address table 25-1 together with the source MAC address a3a2, or, if the lower address a2 of the source MAC address a3a2 of the packet is stored in the lower address memory for receiving packets from the clockwise ring, the source MAC address of the packet is stored in the address table, and, if the lower address a2 of the source MAC address a3a2 of the packet is not stored in the lower address memory for receiving packets from the clockwise ring, the packet (5)Mr1r2a3a2(I7) is sent as it is outside the ring as (6)Mr1r2a3a2(I7) to the router 22. When the packet (6) Mr1r2a3a2 (I7) arrives at the router 22, the source MAC address a3a2 and source IP address I3 of the packet are stored in the ARP table, the output port corresponding to the destination IP address I0 of the packet is found, and the packet is sent to that port. The packet is then transferred as shown in the figure by (7) IPI3I7 (IP indicates an IP address, I3 indicates the source IP address of the mobile terminal 13-2, and I7 indicates the IP address of the destination exchange 23) and arrives at the exchange 23.

[0030] Next, an example is shown in which UDP mobile terminal 13-1, which is connected to a video conference server via an Internet connection server and receives a video conference service, sends packet (8)Mn1a1a2(I0) (M indicates an Ethernet packet, n1 indicates the wireless MAC address of base station 14-1, a1a2 indicates the upper MAC address a1 and the lower MAC address a2 which are the MAC addresses of UDP mobile terminal 13-1, and I0 indicates the IP address of destination server 20) to base station 14-1. Base station 14-1 sends (9)Mr1r2a1a2(I0) to packet add, drop and pass device 6-1 as a wired Ethernet packet. When the packet from UDP mobile terminal 13-1 reaches add, drop and pass-through device 6-1, the lower address a2 of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, and the packet is sent toward vertex device 5 via current optical transmission path 1 of the counterclockwise ring. The packet is then forwarded by (10) Mr1r2a1a2 (I0) as shown in the figure, and arrives at packet add, drop and pass-through device 6-2. When the packet (10) Mr1r2a1a2 (I0) arrives at the packet add, drop, and pass-through device 6-2 on the current optical transmission path 1 of the counterclockwise ring, the lower address of the source MAC address of the packet is not stored in the lower address memory 7, which specifies the sending of the packet outside the ring, so the packet is sent directly to the vertex device 5 as (11) Mr1r2a1a2 (I0) via the optical transmission path 1 of the counterclockwise ring. When the packet arrives at vertex device 5 via packet add, drop, and pass-through device 6-3 on optical transmission path 1 of the counterclockwise ring, the destination MAC address r1r2 of the packet is stored in MAC address table 25-1, so the counterclockwise ring name 1 from which the packet has been transferred and the source MAC address a1a2 are stored in address table 25-1, or if the lower address a2 of the source MAC address a1a2 of the packet is stored in the lower address memory for receiving packets from the clockwise ring, the source MAC address of the packet is stored in the address table, and if the lower address a2 of the source MAC address a1a2 of the packet is not stored in the lower address memory for receiving packets from the clockwise ring, the packet is sent out of the ring as is and headed for router 22.

[0031] When the packet (13) Mr1r2a1a2 (I0) arrives at router 22, if the packet is a communication initiation packet, the source MAC address a1a2 and source IP address I2 of the packet are stored in the ARP table, the output port corresponding to the destination IP address I0 of the packet is found, and the packet is sent to that port. The packet is transferred as shown in the figure by (14) IPI2I0 (IP indicates an IP address, I2 indicates the source IP address of mobile terminal 13-1, and I0 indicates the IP address of server 20, which is the destination) to reach server 20.

[0032] Next, when the UDP mobile terminal 13-2 determines its approach to the destination base station 14-2, which is advertising a base station signal from the LTE (IEEE802.16e) base station 14-1 to nearby mobile terminals, by comparing the received radio wave strength from the base stations 14-1 and 14-2, or by detecting its approach to the base station 14-2 by identifying its location using the GPS function of the mobile terminal 13-2, it sends a request packet (15) Mn1a3a2 (I0) to send a MAC address authentication packet to the source base station 14-1 of the mobile terminal 13-2. Since the MAC address of the mobile terminal 13-2 is stored in a MAC address table (not shown) of its own base station, the source base station 14-1 confirms the MAC address of the mobile terminal 13-2, stores an erasure preparation bit in the MAC address storage location of the mobile terminal in the MAC address table, and sends a MAC address authentication packet having a MAC address confirmation source signal to the destination base station 14-2 of the mobile terminal 13-2 via packet add, drop and pass device 6-1 connected to its own base station and packet add, drop and pass device 6-2 connected to the destination base station of the mobile terminal 13-2. When the authentication packet arrives at the destination base station 14-2 of the mobile terminal 13-2, the base station 14-2 authenticates the MAC address of the wireless channel setting request packet for the mobile terminal that arrived from the mobile terminal 13-2, and sets up a wireless channel for the mobile terminal 13-2. Since both the mobile terminal and the base station are time-synchronized with the nearest GPS satellite with an error of 39 nsec even if the position error is 10 m, the signal from the mobile terminal to the base station is TDM multiplexed transmission with a guard time. The same time slot is used for voice, but the UDP uplink packet is a TDM reserved variable time slot. The IPv6 address of the base station 14-2 is used as the attachment address, and the MAC address a3a2 of the mobile terminal 13-2 is stored in a MAC address table (not shown), and the care-of address is sent to the mobile terminal 13-2 together with an authentication signal. When a packet (16)Mn2a3a2(B2)(I7) (n2 indicates the wireless NIC MAC address of the base station 14-2, and B2 corresponds to the MAC address of the base station 14-2, which is the MAC address portion of the IPv6 care-of address) from the mobile terminal 13-2 that received the packet from the destination base station 14-2 arrives at the base station 14-2, the packet is a packet immediately after the destination base station has been changed when the packet add, drop and pass through device 6-2 connected to the destination base station is a device that connects to a base station approaching the server 20 on the counterclockwise ring 1. Therefore, a signal m indicating that the packet is a packet immediately after the move is inserted into the packet, and the packet is sent to the packet add, drop and pass through device 6-2 as (17)Mr1r2a3a2(B2)m(I7). When the packet (17) Mr1r2a3a2(B2)m (I7) from the UDP mobile terminal 13-2 reaches the add, drop and pass-through device 6-2, the lower address a2 of the source MAC address of the packet is not stored in the duplicated use lower address memory 12 and is not stored in the lower address memory 7 that specifies packet transmission outside the ring, so the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 that specifies packet transmission outside the ring and is also stored in the duplicated use lower address memory 12. The duplicated use lower address memory 12 is configured to store either the entire lower MAC address or the upper address in the address position of the memory accessed by the lower address part of the lower MAC address, and simultaneously stores two temporary storage timer bits (11) and erases bit 1 from the two bits one bit at a time at a fixed period. When the second bit, bit 1, is erased, if the desired lower address is stored in the lower address memory 7 that specifies packet transmission outside the ring, either the entire lower MAC address or the upper address part is erased from the address position of the memory accessed by the lower address part of the lower MAC address. The packets stored in the lower address memory 7 and the overlapping use lower address memory 12 are sent to the vertex device via the counterclockwise ring optical transmission path 1. When the packet (18) Mr1 r2 a3 a2 (I7) arrives at the packet add, drop and pass-through device 6-3, the packet is transferred as is by (19) Mr1 r2 a3 a2 (I7) via the counterclockwise ring optical transmission path 1 as shown in the figure, and sent to the vertex device 5. When the packet (19) Mr1r2a3a2 (I7) arrives at the receiving circuit 25-1 of the vertex device 5, the destination MAC address r1r2 of the packet is stored in the MAC address table 25-1, so the name of the counterclockwise ring 1 from which the packet has been transferred and the source MAC address a3a2 are stored in the address table 25-1, or if the lower address a2 of the source MAC address a3a2 of the packet is stored in the lower address memory for receiving packets from the clockwise ring, the source MAC address of the packet is stored in the address table, and if the lower address a2 of the source MAC address a3a2 of the packet is not stored in the lower address memory for receiving packets from the clockwise ring, the packet is sent out of the ring as is and headed for the router 22.

[0033] When the packet (20) Mr1r2a3a2 (I7) arrives at the router 22, it is not a communication initiation packet or a response packet to a communication initiation packet, and therefore the source MAC address a3a2 and source IP address I3 of the packet are stored in the ARP table, so the packet is taken into the router 22, an output port corresponding to the destination IP address I0 of the packet is found, and the packet is sent to that port. The IP packet of the packet is sent to the exchange 23. The packet is transferred as shown in the figure by IPI3I7 (IP indicates an IP address, I3 indicates the source IP address of the mobile terminal 13-2, and I7 indicates the IP address of the destination exchange 23) and arrives at the exchange 23.

[0034] Next, when a packet (21) IPI0I2 (IP indicates an IP address, I2 is the IPv6 address or IPv4 address of the terminal 13-1, and I0 is the IP address of the video conference server) that is not a communication initiation packet arrives at the router 22 from the video conference server, if the packet is an IPv6 address, the destination MAC address a1a2 paired with the destination IPv6 address I2 of the packet is copied from the MAC address portion of the destination IPv6 address, and the MAC packet (22) Ma1a2r1r2 (I2) used as the MAC header address of the MAC packet is sent to the apex device 5 of the ring network. If the packet is an IPv4 address, the destination MAC address a1a2 paired with the destination IP address I2 of the packet is found from an ARP table (not shown), and the MAC packet (22) Ma1a2r1r2 (I2) used as the MAC header address of the MAC packet is sent to the apex device 5 of the ring network. When the packet arrives at the vertex device 5, the destination MAC address of the packet is stored in the MAC address table 25-1, and the counterclockwise ring name 1 is stored in that MAC address storage location, or the lower address a2 of the destination MAC address a1a2 of the packet is stored in the lower address memory together with the counterclockwise ring name 1, so the packet is sent to the optical transmission path 2 of the clockwise ring, which is the opposite ring of the left ring name 1.

[0035] When the packet (23) Ma1a2r1r2 (I2) is transferred on the clockwise ring 2 and arrives at the packet add, drop, and pass-through device 6-3, the lower address a2 of the destination MAC address of the packet (23) Ma1a2r1r2 (I2) is not stored in the duplicated use lower address memory 12 or the lower address memory 7 that specifies packet transmission outside the ring, so the packet is sent to the clockwise ring 2. When the packet (24)Ma1a2r1r2(I2) arrives at the packet add, drop and pass device 6-2, the lower address a2 of the destination MAC address of the packet is stored in the duplicated use lower address memory 12, so the packet is copied and the copy packet is sent to the clockwise ring as (26)Ma1a2r1r2(I2), and the original packet is sent outside the ring as (25)Ma1a2r1r2(I2). Since the destination MAC address a1a2 of the packet (25)Ma1a2r1r2(I2) is not stored in the MAC address table (not shown) of the base station 14-2, the packet is discarded.

[0036] When the packet (26)Ma1a2r1r2(I2) arrives at the packet add, drop and pass device 6-1, the lower address a2 of the destination MAC address of the packet is not stored in the duplicated use lower address memory 12 at this point, and the lower address of the destination MAC address of the packet is stored in the lower address memory 7 that specifies packet transmission outside the ring, so the packet is sent outside the ring. When the packet arrives at the base station 14-1, the destination MAC address a1a2 of the packet (27)Ma1a2r1r2(I2) is stored in a MAC address table (not shown), so the packet is sent to the mobile terminal 13-1 as (28)Ma1a2n1(I2). When a response packet (29) Mn1 a1 a2 (I0) of the packet (28) Ma1 a2 n1 (I2) from the mobile terminal 13-1 arrives at the base station 14-1, the packet is sent as (30) Mr1 r2 a1 a2 (I0) via the packet add, drop and pass through device 6-1 as Mr1 r2 a1 a2 (I0) to the counterclockwise ring 1. When the packet (30) Mr1 r2 a1 a2 (I0) arrives at the packet add, drop and pass through device 6-2, since the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 that specifies packet transmission outside the ring, the lower address in the lower address memory 7 is erased, the lower address is stored in the duplicated use lower address memory 12, and the packet is sent in the counterclockwise ring forward direction as (31) Mr1 r2 a1 a2 (I0). The deletion of the lower address a2 from the lower address memory 7, which designates packet transmission outside the ring, is shown by drawing a horizontal line in the figure.

[0037] Next, a second embodiment of the present invention will be described with reference to Fig. 2. This embodiment is an example of operation for recovering from a failure in a ring network, in which a mobile terminal accommodated in a base station connected to a packet add, drop and pass device in a double ring network, which is connected by an optical transmission line, transfers information as a MAC packet to a router connected to the ring network, and performs handover that also enables the mobile terminal to receive TCP packets and UDP one-way packets in a packet forwarding system between a server or a switch connected to the ring network via the router. The server is an Internet connection server or a content server. From the NIC of the ring network interface of the router 22 to the NIC of the wireless interface of the base station via the ring network, one MAC domain is provided. The content server may be a cloud center.

[0038] Figure 2 shows an example of operation when a transmission path failure occurs at symbol 30 between packet add, drop and pass devices 6-2 and 6-3 in Figure 1, and the packet is looped back to the clockwise ring at the left-handed ring exit of packet add, drop and pass device 6-2. The packet operation sequence (1) to (31) shown in Figure 2 is the same as that shown in Figure 1. However, in Figure 2, the packet at (31) is looped back at loopback point 40. When a fault occurs in the ring network, a packet bound for the clockwise ring transmission line adjacent to the fault point is not looped back to the counterclockwise ring receiving side (an example of a packet add, drop and pass device 6-3), but a packet bound for the counterclockwise ring transmission line adjacent to the fault point is looped back at symbol 40 (an example of a packet add, drop and pass device 6-2), and the looped back packet (31) Mr1r2a1a2 (I0) is When a packet arrives at the input buffer of the right-handed ring receiving side of the add, drop and pass device 6-2 from the right-handed ring receiving side, the destination MAC address r1r2, which is the NICMAC address of the ring network interface of the router 22 of the packet, is stored in the ring transmission line port address table 9 of the downstream exit of the packet. If the packet does not hold a steering bit and the add, drop and pass device of the packet itself is a device that has looped back the packet to be sent forward on the left-handed ring to the right-handed ring receiving side, even if the lower address of the source MAC address of the packet is stored in the lower address memory 7 that specifies packet sending out of the ring, writing to the duplicated use lower address memory 12 is not performed. However, if the add, drop and pass device of the packet itself is not a device that has looped back the packet to be sent forward on the left-handed ring, and the lower address of the source MAC address of the packet is stored in the lower address memory 7 that specifies packet sending out of the ring, the lower address of the lower address memory is erased, and the lower address of the source MAC address of the packet is written to the duplicated use lower address memory 12. The packet is directed to packet add / drop and pass-through device 6-1 as (32) Mr1r2a1a2 (I0). In addition, when a packet having the NIC MAC address of the ring network interface of router 22 as its destination MAC address is forwarded on clockwise ring 2 and the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, the lower address in the lower address memory may be erased and stored in the duplicated use lower address memory.

[0039] When the looped back packet arrives at the packet add / drop and pass device 6-1, the destination MAC address r1r2 of the packet is stored in the ring transmission line port address table 9 of the downstream exit of the packet, and when the lower address of the source MAC address of the packet is stored in the lower address memory that specifies packet transmission outside the ring, the lower address of the source MAC address of the packet is deleted from the lower address memory 7 that specifies packet transmission outside the ring, and the lower address is stored in the duplicated use lower address memory 12. When the packet arrives at the vertex device 5, which is one of the ring node devices, as (33)Mr1r2a1a2(I0), the destination MAC address r1r2 of the packet is stored as port number 3 in the MAC address table 25-1, so the source MAC address a1a2 of the packet and the clockwise ring name 2 from which the packet has been transferred are stored in the MAC address table 25-1 as a pair. In the figure, the ring name 1 of the MAC address a1a2 is crossed out with a horizontal line and the port number 2 is stored.

[0040] Next, when an incoming IP packet (34) IPI7I3 (I7 is the IP address of the switch, and I3 is the IP address of the mobile terminal 13-2) from the switch arrives at the router 22, a periodic location registration packet from the mobile terminal 13-2 arrives at the router 22 on the clockwise ring 2, and since the source MAC address and source IP address are stored in an ARP table (not shown), the router searches the ARP table based on the destination IP address I3 of the IP packet (34) IPI7I3, converts it to a MAC packet Ma3a2r1r2 (I3), adds a steering bit from the vertex device 5, and sends it to the counterclockwise ring as (35) Ma3a2r1r2 (I3). When the packet arrives at packet add, drop, and pass-through device 6-1, the packet has been assigned a steering bit and the lower address a2 of the packet's destination MAC address a3a2 is stored in duplicate-use lower address memory 12, so the packet is copied and the copy packet is sent to the front of the counterclockwise ring as (37)Ma3a2r1r2 (I3), and the original packet of the copy packet is sent outside the ring as (36)Ma3a2r1r2 (I3). When the packet (37) Ma3a2r1r2 (I3) arrives at the packet add, drop, and pass device 6-2, a steering bit has been added to the packet, and the lower address a2 of the destination MAC address a3a2 of the packet is stored in the duplicated-use lower address memory 12, so the packet is copied and the copy packet is sent forward on the ring in a counterclockwise direction. However, because a steering bit has been added, the copy packet is discarded without looping back, and the original packet of the copy packet is sent outside the ring and arrives at the mobile terminal 13-2 as (38) Ma3a2n2 (I3).

[0041] Next, when a packet (39) Mn2a3a2 (I7) from the mobile terminal 13-2 is sent to the base station 14-2 and the packet Mr1r2a3a2 (I7) arrives at the packet add, drop and pass device 6-2, the destination MAC address r1r2 of the packet is stored in the ring transmission line port address table 9, so the packet is given a steering bit and sent to the right-handed ring 2 via the input FIFO on the right-handed ring receiving side. When the packet arrives at the packet add, drop and pass device 6-1, the destination MAC address r1r2 of the packet is stored in the ring transmission line port address table 9, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory 12, so the packet is transferred to the vertex device 5 as (40) Mr1r2a3a2 (I7). When the packet arrives at the vertex device 5, the destination MAC address r1r2 of the packet is stored in the MAC address table 25-1, so the source MAC address a3a2 of the packet and the clockwise ring name 2 through which the packet has been transferred are stored as a pair in the MAC address table 25-1. In the figure, the ring name 1 of the MAC address a3a2 is crossed out and the ring name 2 is stored. The ring name of a packet arriving at vertex device 5 from the router with a destination MAC address of a1a2 or a3a2 is read as 2 from MAC address table 25-1, so the packet is sent to counterclockwise ring 1. A steering bit is added to packets sent to the counterclockwise ring. When a packet with a destination MAC address of a1a2 and a steering bit arrives at packet add, drop and pass-through device 6-1 on the counterclockwise ring, the destination MAC address of the packet is stored in duplicated use lower address memory 12, so the packet is copied and the copy packet is sent to the front of the counterclockwise ring, and the original packet of the copy packet is sent out of the ring.

[0042] When switching back after a transmission path failure is restored, the OAM packet from the apex device clears the stored addresses in the ring transmission path port address table 9 of the add, drop and pass-through devices for all packets in the ring network, and the ring names used for the MAC addresses of all mobile terminals in the MAC address table 25-1 of the apex device are changed to counterclockwise ring name 1.

[0043] If a transmission path failure occurs at symbol 30 between devices 6-2 and 6-3 for adding, dropping and passing packets, and the packet is looped back at devices 6-2, 6-3 for adding, dropping and passing packets on both sides of the failure point, a loopback bit is added to the looped back packet, and the packet with the loopback bit added passes through all devices until the second loopback occurs, at which point the loopback bit is removed and the original operation is restored. However, this has the disadvantage of narrowing the transmission bandwidth.

[0044] Furthermore, when the wireless section is TCP, the response from the mobile terminal will be a NAK, but between the base station and the server an ACK packet is sent from the TCP circuit of the base station. Therefore, although erroneous dropping of packets from the clockwise ring of the device through which the packets are added, dropped, or passed cannot be handled by resent packets from the server, writing to the duplicated use lower address memory is possible with packets from the counterclockwise ring of the device through which the packets are added, dropped, or passed. On the other hand, when the wireless section uses UDP, the bandwidth of the upstream signal in the wireless section is narrowed down to a lower speed compared to the downstream signal, so an immediate response from the mobile terminal cannot be expected. Therefore, in the present invention, a method is adopted in which the lower address of the source MAC address of a packet immediately after the mobile terminal moves to the base station is stored in the duplicated-use lower address memory of the packet add, drop and pass device, and the packet arrives at the packet add, drop and pass device from the right-handed ring and its destination is a device ahead of the packet add, drop and pass device on the right-handed ring, and the lower address of the destination MAC address stored in the duplicated-use lower address memory is copied and sent to the front of the right-handed ring as well.

[0045] In the first and second embodiments, the type / length field of the header of the MAC packet transferred is set to a value larger than the maximum packet length of 1518 bytes (binary 10111101110) and smaller than 0600 in hexadecimal instead of a specific type such as an IPv4 address, and the first and fifth bits of the binary representation of 1518 bytes are used as control bits, or the fifth bit of the binary representation of 1518 bytes is set to bit 1, and 15 patterns of the lower four bits are freely used for one control signal in one packet. The former cannot be used for types such as ARP packets, so it becomes a replacement control bit for the majority of IPv4 packet types or IPv6 packet types on the transmission line, and if it is used as a control bit for a packet immediately after a base station moves, it must be written in place of the type bit of the IPv4 packet or IPv6 packet. The steering bit packet is usable because it does not loop back, but it cannot be used as a loopback bit. On the other hand, the second and third bits of the first four bits of the packet type field are left as empty bits. These two bits are not used as packet type bits for IPv4, IPv6, arp, etc., so if these two bits are removed from the packet type determination bits, they may be usable as control bits. Another method is to use the packet length field in the MAC header of the IEEE 802.3 MAC packet as a control bit, in which case the packet is transmitted in 8B10B code.

[0046] Next, the operation flow of the device for adding, dropping and passing packets in the first embodiment is shown in Figures 3A, 3B and 3C, and the sequencer circuit is shown in Figure 4. Next, the operation of Figures 3A, 3B and 3C will be described. (b1), (b2), (b3), (c1), (c2), (c3) etc. in the flow symbols describing the operation of the flow diagram and B1, B2, C1, C2 etc. described outside the flow symbols are written in sequence diagram 4, (b1), (b2), (b3), (c1), (c2), (c3) etc. indicate the time positions in sequence diagram 4 where the corresponding operations described in Figure 3 are performed, and B1, B2, C1, C2 etc. are described in correspondence with Figure 3 as input signals to the AND gate of sequence diagram 4. Figure 3 shows the operation in a normal state that is not a steering state. In FIG. 3A, 100 indicates as (b1) whether a packet has been received from the clockwise ring, with a signal for YES being (B1) and a signal for NO being (E1), 101 indicates as (b2) whether the lower address of the destination MAC address of the received packet is stored in the duplicated-use lower address memory, with a signal for YES being (B2) and a signal for NO being (C1), 102 copies the received packet, inputs the copied packet into the output buffer at the front of the clockwise ring, and the original packet of the copied packet is input into the output buffer to the dependent base station, indicating that the packet is OK (b3). 103 indicates as (c2) whether the lower address of the destination MAC address of the received packet is stored in the lower address memory that specifies packet transmission outside the ring, and the signal for YES is (C2) and the signal for NO is (D1). 104 copies the received packet, inputs the copy packet to the output buffer in front of the clockwise ring, inputs the original copy packet to the output buffer to the dependent base station, and discards the packet to the front of the clockwise ring of the two packets (c3). 105 copies the received packet, inputs the copy packet to the output buffer in front of the clockwise ring, inputs the original copy packet to the output buffer to the dependent base station, and discards the packet to the dependent base station of the two packets (d2).

[0047] In FIG. 3B, 106 indicates as (e2) whether a packet has arrived from the base station, the signal for YES is (E2) and the signal for NO is (G1), 107 indicates as (e3) whether the lower address of the source MAC address of the received packet is not stored in the duplicated-use lower address memory and is not stored in the lower address memory specifying packet transmission outside the ring, the signal for YES is (E3) and the signal for NO is (F1), and 108 stores the source MAC lower address of the received packet in the lower address memory specifying packet transmission outside the ring and in the duplicated-use lower address memory, and transmits the received packet to the counterclockwise ring output buffer (e4). 109 indicates as (f2) whether the lower address of the source MAC address of the received packet is not stored in the duplicated use lower address memory and is stored in the lower address memory that specifies packet transmission outside the ring, the signal for YES is (F2) and the signal for NO is (G1), 110 stores the source MAC lower address of the received packet in the lower address memory that specifies packet transmission outside the ring and transmits the received packet to the counterclockwise ring output buffer (f3). 111 transmits the received packet to the counterclockwise ring output buffer (g2). 112 indicates whether a packet has been received from the counterclockwise ring as (h2), and if YES, the signal is (H2), and if NO, the timer is out and transitions to (a). In FIG. 3C, 113 indicates whether the lower address of the source MAC address of the received packet is stored in the lower address memory that specifies packet transmission outside the ring as (h3), and if YES, the signal is (H3), and if NO, the signal is (I1). 114 erases the lower address of the source MAC address of the received packet from the lower address memory that specifies packet transmission outside the ring, stores the lower address in the overlapping use lower address memory (h4), and sets the output signal to (H4). 115 sends the received packet to the counterclockwise ring output buffer (h5). 116 sends the received packet to the counterclockwise ring output buffer (i2). As shown in FIG. 5, the timeout signal (a) of the timer of 130 is set so that the timer value times out after the flow operation is completed, regardless of the flow operation of FIG. 3.

[0048] Next, the operation of FIG. 4, part of the sequence diagram, will be described. 450 is a JKFF, and 451 is an AND circuit. All JKFFs are reset by the timeout signal (a) of the timer shown in FIG. 5. When the timer out signal (a) is input to JKFFs 450-1 and 452-1, the Q bars of JKFFs 450-1 and 450-2 become 1, and the signal B1 after the operation (b1) of 452-1 is input to the AND circuit 451-1, so that the output signal of the AND circuit 451-1 is input to J of JKFF 450-1, and the output becomes 1. The operation (b2) of 452-2 is performed at the output 1, and the output signal B2 is input to the AND circuit 451-2, and the output 1 is input to J of JKFF 450-2, so that the output of JKFF 450-2 becomes 1, and the operation (b3) of 452-3 is performed at the output 1. Since the NOT signal of Q output 1 and Q-bar output of JKFF 450-2 is input to AND circuit 451-6, the output signal C1 is input to J of JKFF 450-4, the operation of (c2) of 453-2 is performed at output 1, and the output signal C2 is input to the AND circuit, the operation of (c3) of 453-3 is performed at output 1. Signal E1 is generated from the output of JKFF 450-1 in the same manner as signal C1. Signal D1 is generated from the output of JKFF 450-4 in the same manner as signal C1. Other branch sequencer diagrams are not shown in FIG. 4, but they would have the same form as above.

[0049] Next, the operation of the sequencer driving circuit shown in FIG. 5 will be described. FIG. 5 is an example of a device for adding, dropping and passing packets in a steering state when a ring transmission line failure occurs. When the destination MAC address of a packet added on the ADD line from the base station is stored in the ring transmission line port address table in front of the right-handed ring, or when the device for adding, dropping and passing packets is in steering mode, a steering packet with steering packet bits is input to the input FIFO 400 of the right-handed ring received packet and the steering packet FIFO 420 in parallel. The output of the FIFO 400 is 8-bit parallel data 405, packet start bit 406 and packet end bit 407, and the output of the FIFO 420 is 8-bit parallel data 425, packet start bit 426 and packet end bit 427. The FIFO 420 operates with an 8-bit parallel clock 1, and the FIFO 400 operates with an 8-bit parallel clock 2, with the clock 1 and the clock 2 shifted by half a clock. A signal 426 indicating that the start bit of a packet has been read from the FIFO 420 and a signal 407 indicating that the end bit of a packet has been read from the FIFO 400 are ORed in an OR circuit 416 to generate a read clock 2 stop signal 413 for the FIFO 400. Similarly, a signal 406 indicating that the start bit of a packet has been read from the FIFO 400 and a signal 427 indicating that the end bit of a packet has been read from the FIFO 420 are ORed in an OR circuit 428 to generate a read clock 1 stop signal for the FIFO 420. A signal 409 indicating the start bit of a packet in the FIFO 400 or a signal 419 indicating the start bit of a packet in the FIFO 420 serves as a start signal for the 550-byte timer and the 1512-byte timer. If the end bit signal of the packet (either 427 or 407) is input to the 550-byte timer before the 550-byte timer times out, the 550-byte timer outputs a timeout signal 411 to stop the operation of the 1512-byte timer.On the other hand, if the end-of-packet bit signal (either 427 or 407) is not input to the 550-byte timer before the 550-byte timer times out, the 550-byte timer does not output a timeout signal 411, and a timeout signal 412 from the 1512-byte timer is input to the OR circuit 403. The OR signal of signals 411 and 412 becomes a reset signal (a) for all JKFFs in the sequencer circuit, and also becomes a read resume signal for FIFO 400 and FIFO 420. The 8-bit parallel signal 405 read from the FIFO 400 or the 8-bit parallel signal 425 read from the FIFO 420 is transferred with an 8-bit parallel clock and is copied and input to the output FIFO for one packet forward on the clockwise ring and to the output FIFO for one packet for transmission to the base station together with the first bit of the packet and the last bit of the packet. If the copied packet is determined to be unnecessary by the sequencer, it is discarded. The FIFO may be replaced with a shift register.

[0050] Next, a sequencer driver circuit of a device for adding, dropping and passing packets when looping back on both sides of a fault point without steering when a ring network fault occurs will be described with reference to Fig. 6. A clockwise ring received packet is input to an input FIFO 500. The output of the FIFO 500 is 8-bit parallel data 520, a packet start bit 521 and a packet end bit 522. The FIFO 500 operates with an 8-bit parallel clock, and a signal 522 obtained by reading the end bit of the packet from the FIFO 500 becomes a stop signal for the read clock of the FIFO 500. The signal 521 of the first bit of the packet of the FIFO 500 becomes start signals 510 and 511 of the 550-byte timer and the 1512-byte timer. The signal 521 of the first bit of the packet of the FIFO 500 becomes a set signal for the latch circuits 503-1 and 503-3. If the bit signal 522 at the end of the packet is input to the AND circuit 504-1 before the 550-byte timer times out and the latch circuit 503-2 is set at the output, the timeout signal of the 550-byte timer resets the latch circuits 503-1 and 503-3 via the AND circuit 504-2, so the timeout signal of the 1512-byte timer stops at the AND circuit 504-3. On the other hand, if the bit signal 522 at the end of the packet does not set the latch circuit 503-2 before the 550-byte timer times out, the timeout signal of the 550-byte timer is stopped at the AND circuit 504-2 and does not reset the latch circuit 503-2, so the timeout signal 412 of the 1512-byte timer passes through the AND circuit 504-3 and is input to the OR circuit 505. An OR signal 512 of the output signal of the AND circuit 504-2 and the output signal of the AND circuit 504-3 serves as a reset signal (a) for all JKFFs in the sequencer circuit, and also serves as a read restart signal for the FIFO 500. The 8-bit parallel signal 520 read from the FIFO 500 is transferred with an 8-bit parallel clock, and is copied and input to the output FIFO for one packet forward on the clockwise ring and to the output FIFO for one packet for transmission to the base station, together with the start bit and end bit of the packet. If the copied packet is determined to be unnecessary by the sequencer, it is discarded. A shift register may be used instead of the FIFO.

[0051] The configuration method of the lower address memory that specifies the packet add, drop and pass device's packet send out of the ring in the first embodiment is disclosed in Chapter 3 "Address memory method using data storage area as address" on page 44 of "Proposal of MAC operation type tree-shaped ring network that forwards packets having only source terminal address in both directions" in Communication Method vol 113 No, 207, September 12-13, 2013 of the Institute of Electronics, Information and Communication Engineers Technical Report (IEICE Technical Report CS2013-28-CS2013-40) and in Chapter 3 "Packet's add, drop and pass equipment" in "Handovers using ring network composed of ring node equipment including lower MAC address memory, and top equipment" in Session 10-5 of ICETC2022 at https: / / www.ieice.org / publications / proceedings. It is also disclosed in JP 2019-097045 (Address memory method). This method can also be configured as shown in FIG. 7 as a principle diagram. In FIG. 7, the output of 32 bits of SRAM output data (70) is latched by a latch circuit (55), and the latch output signal, a bit 0 write signal (59), and the output (60) obtained by decoding the lower 5 bits (58) of the lower MAC address by a decoder (53) are input to a logic circuit (54), which sends the signal to the outside and writes it to the SRAM from the CPU. [Explanation of symbols]

[0052] 1. Counterclockwise ring optical transmission line 2. Clockwise ring optical transmission line 5 Vertex device 6-1, 6-2, 6-3 Packet Add, Drop and Pass Devices 7 Lower address memory that specifies packet transmission outside the ring 12 Overlapping lower address memory 13-1, 13-2, 13-3 Mobile terminals 14-1,14-2,14-3 Base station 15. Mobile terminal movement 20 Servers 22 Router 23 Switchboard 25-1 MAC address table of apex device

Claims

1. a plurality of packet add, drop and pass devices are inserted into a ring network of an optical transmission path 2 of a clockwise ring and an optical transmission path 1 of a counterclockwise ring, a base station is connected to the packet add, drop and pass devices, and a mobile terminal under the base station has a function of receiving packets arriving from the counterclockwise ring of the ring network, or from the clockwise ring when a fault occurs in the ring network, and transferring the packets to a router, and a function of blocking the passage of a packet having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packet is stored in a MAC address table of the device itself, the system allowing packets to travel between the mobile terminal and the router across the ring network as TCP or UDP Ethernet frames of call signals or the like, and between the router and the server or the switch as IP packets, in order to communicate with a destination server via the router connected to the router for TV lectures, TV conferences involving call signals, and content distribution, or to provide a call service with a switch via the router, In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, Regardless of whether the packet is a packet immediately after the mobile terminal changes the destination base station or immediately after the change, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory specifying packet transmission outside the ring; otherwise, the packet is sent out counterclockwise to the front of the ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a means for, when a lower address of the source MAC address of the packet is stored in a lower address memory 7 that designates packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that designates packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise transferring the packet directly forward to a router 22 to which a server 20 is connected via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, means for, when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of a destination MAC address of the packet is stored in a duplicated use lower address memory, copying the packet and sending the copied packet forward in a clockwise direction and sending the original packet of the copied packet out of the ring, if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory specifying packet transmission out of the ring, sending the packet out of the ring, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory specifying packet transmission out of the ring, sending the packet forward in a clockwise direction; The mobile terminal sends a location registration packet having the MAC address of the mobile terminal to the exchange via the ring network, or sends a mail reception access packet to the mail reception server, and when the packet arrives at a packet add, drop and pass device from outside the ring, if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and if the lower address of the source MAC address of the packet specifies packet transmission outside the ring, and if the location registration packet arrives at a device for adding, dropping and passing a packet, or if the mail reception access packet arrives at a device for adding, dropping and passing a packet, and the lower address of the source MAC address of the packet is stored in lower address memory 7 that specifies packet sending out of the ring, the lower address of the source MAC address of the packet is erased from lower address memory 7 that specifies packet sending out of the ring and the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and otherwise the packet is forwarded via an optical transmission path to router 22 to which server 20 is connected.

2. The system according to claim 1, characterized in that the device for adding, dropping and passing packets comprises means for storing two bits of a lower address in the duplicated use lower address memory when the storage of a lower address in the lower address memory specifying packet transmission outside the ring and the storage of a lower address in the duplicated use lower address memory are performed simultaneously, erasing the two bits one bit at a time at a fixed period, and erasing the lower address from the duplicated use lower address memory when the second bit is erased and the lower address is stored in the lower address memory specifying packet transmission outside the ring.

3. 2. The system according to claim 1, wherein the overlapping use lower address memory is configured to store the upper part of the lower MAC address excluding the lower part at an address position of a memory accessed by the lower part of the lower MAC address.

4. The system described in claim 2, characterized in that the duplicated use lower address memory is configured to store the upper part of the lower MAC address excluding the lower part at an address location of a memory accessed by the lower part of the lower MAC address, and the two bits stored at the lower address memory location are stored at the rear of the upper part.

5. The system according to claim 1, characterized in that when a lower address is stored in a lower address memory that specifies packet sending outside the ring of the device for adding, dropping and passing the packet and when the lower address is stored in a duplicated use lower address memory, if the lower address of the MAC address is stored in the lower address memory that specifies packet sending outside the ring after a certain time from that point, the lower address is erased from the duplicated use lower address memory.

6. In the packet add, drop and pass device, 8-bit parallel data of a packet arriving from a clockwise ring and 10 bits of the first bit of a frame and the last bit of a frame are input to an input FIFO, and when the first bit of the frame is read from the FIFO by a sequencer circuit, a 550-byte timer and a 1500-byte timer are started to operate, and if the last bit of the frame is read before the 550-byte timer times out, reading from the FIFO is stopped, the 1500-byte timer is reset by a timeout pulse of the 550-byte timer, and the sequencer circuit is started. and means for resetting all JKFFs of said sequencer circuit and resuming reading of said FIFO regardless of the end of a sequence in said sequencer circuit, while stopping operation of said 550 byte timer if an end of frame bit is not read before a 550 byte timer times out, and stopping reading from said FIFO if an end of frame bit is read before a 1500 byte timer times out, and resetting all JKFFs of said sequencer circuit and resuming reading of said FIFO regardless of the end of a sequence in said sequencer circuit.

7. In the event of a ring network failure, means for looping back packets at add, drop and pass devices on both sides of the failure point, adding a loopback bit when the packet is looped back, allowing the packet to pass through all devices up to the second loopback point, and removing the loopback bit at the second loopback; or A packet on the left-handed ring transmission line of a packet add, drop and pass device adjacent to the failure point is looped back to an input buffer on the receiving side of the right-handed ring, and when a packet whose destination MAC address is the NIC MAC address of the ring network interface of the router 22 arrives from the receiving side of the right-handed ring at the packet add, drop and pass device, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; when the packet arrives at the add, drop and pass device of the packet, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; On the other hand, when a packet from a base station outside the ring arrives at a device for adding, dropping, or passing the packet, if the destination MAC address of the packet is stored in the ring transmission line port address table, or if the device for adding, dropping, or passing the packet is in a steering state, a steering bit is added to the packet, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, nothing is done; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and the packet is sent forward to the front of the ring in a clockwise direction; On the other hand, if the packet is not a packet immediately after the mobile terminal changes the destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in a lower address memory that specifies packet transmission outside the ring, and transmit the packet to the front of the ring in a clockwise direction; When the packet arrives at a packet add, drop and pass through device from the clockwise ring, if a lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, the lower address of the lower address memory is erased, the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and the packet is sent to the front of the clockwise ring; When the packet arrives at a vertex device from the clockwise ring, store the lower address of the source MAC address of the packet in a lower address memory, and forward the packet to a server or switch via the router 22; When a packet from a server or an exchange arrives at a vertex device via a router 22, if the lower address of the destination MAC address of the packet is stored in a lower address memory, the packet is transferred on a counterclockwise ring with a steering bit added, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory, the packet is transferred on a clockwise ring without a steering bit added. The system of claim 1 further comprising:

8. a base station is connected to the packet adding, dropping and passing device; a mobile terminal under the base station has a function of receiving a packet arriving from the left-handed ring of the ring network or from the right-handed ring when a fault occurs in the ring network, and transferring the packet to a router; and a function of blocking the passage of a packet having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packet is stored in a MAC address table of the device itself; a method for transmitting data between the mobile terminal and the router via the ring network as an Ethernet frame of TCP or UDP such as a call signal, and between the router and the server or the switch as an IP packet, in order to communicate with a destination server via the router connected to the router for a video lecture, a video conference involving a call signal, or content distribution, or to provide a call service with a switch via the router, In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, Regardless of whether the packet is a packet immediately after the mobile terminal changes the destination base station or immediately after the change, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and is stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory specifying packet transmission outside the ring; otherwise, the packet is sent out counterclockwise to the front of the ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a step of, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 that specifies packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that specifies packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise forwarding the packet as it is to a router 22 to which a server 20 is connected via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, a step of copying the packet and sending the copy packet forward in a clockwise direction when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of the destination MAC address of the packet is stored in a duplicated use lower address memory, sending the packet out of the ring if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring, sending the packet out of the ring if the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring, and sending the packet forward in a clockwise direction when the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring; When a location registration packet having a MAC address of a mobile terminal is sent to a switch via a ring network, or when a mail reception access packet of the mobile terminal is sent to a mail reception server, and the packet arrives at a packet add, drop and pass device from outside the ring, if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the source MAC address of the packet is not stored in the lower address memory specifying packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in the lower address memory 7 specifying packet transmission outside the ring and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and when the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the source MAC address of the packet arrives at a device for adding, dropping and passing the packet from outside the ring, and when the location registration packet or the mail reception access packet arrives at a device for adding, dropping and passing a packet, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 specifying packet sending out of the ring, the lower address of the source MAC address of the packet is erased from the lower address memory 7 specifying packet sending out of the ring and the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and otherwise the packet is forwarded via an optical transmission path to a router 22 to which a server 20 is connected.

9. a base station is connected to the packet adding, dropping and passing device; a mobile terminal under the base station has a function of receiving a packet arriving from the left-handed ring of the ring network or from the right-handed ring when a fault occurs in the ring network, and transferring the packet to a router; and a function of blocking the passage of a packet having a NIC MAC address of a ring network interface of the router as a source MAC address when the source MAC address of the packet is stored in a MAC address table of the device itself; a method for transmitting data between the mobile terminal and the router via the ring network as an Ethernet frame of TCP or UDP such as a call signal, and between the router and the server or the switch as an IP packet, in order to communicate with a destination server via the router connected to the router for a video lecture, a video conference involving a call signal, or content distribution, or to provide a call service with a switch via the router, In normal operation of the ring network, When a packet from the mobile terminal arrives at a packet add, drop and pass-through device of the ring network, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring, If the packet is not a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring; When a packet to be transferred on the counterclockwise ring arrives at a packet add, drop, and pass-through device from the counterclockwise ring, a step of, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 that specifies packet transmission outside the ring, erasing the lower address of the source MAC address of the packet from the lower address memory 7 that specifies packet transmission outside the ring, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and otherwise forwarding the packet as it is to a router 22 to which a server 20 is connected via an optical transmission line; When a packet from the server 20 arrives at the apex device 5 of the ring network via the router 22, the packet is sent to the clockwise ring, a step of copying the packet and sending the copy packet forward in a clockwise direction when the packet arrives at a packet add, drop and pass device, and regardless of whether the packet is a communication initiation packet or not, if a lower address of the destination MAC address of the packet is stored in a duplicated use lower address memory, sending the packet out of the ring if the lower address of the destination MAC address of the packet is not stored in the duplicated use lower address memory and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring, sending the packet out of the ring if the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring, and sending the packet forward in a clockwise direction when the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies packet transmission out of the ring; When a location registration packet having a MAC address of a mobile terminal is sent to a switchboard via a ring network, or when a mail reception access packet of the mobile terminal is sent to a mail reception server, and the packet arrives at a packet add, drop, and pass-through device from outside the ring, and the packet is a packet immediately after the mobile terminal has changed its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring, If the packet is not a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, and if the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, the packet is sent directly to the front of the counterclockwise ring; and when the location registration packet or the mail reception access packet arrives at a device for adding, dropping and passing packets, if the lower address of the source MAC address of the packet is stored in a lower address memory 7 that specifies packet transmission outside the ring, the lower address of the source MAC address of the packet is erased from the lower address memory 7 that specifies packet transmission outside the ring, the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and otherwise the packet is forwarded as is via an optical transmission path toward a router 22 to which a server 20 is connected.

10. In the event of a ring network failure, A step of looping back the packet at the add, drop and pass devices on both sides of the failure point, adding a loopback bit when the packet is looped back, passing the packet with the loopback bit through all the devices up to the point where the packet is looped back a second time, and removing the loopback bit at the second loopback; or A packet on the left-handed ring transmission line of a packet add, drop and pass device adjacent to the failure point is looped back to an input buffer on the receiving side of the right-handed ring, and when a packet whose destination MAC address is the NIC MAC address of the ring network interface of the router 22 arrives from the receiving side of the right-handed ring at the packet add, drop and pass device, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; when the packet arrives at the add, drop and pass device of the packet, storing the destination MAC address of the packet in a ring transmission line port address table in front of the clockwise ring, or placing the add, drop and pass devices of the packet in a steering state, and if the lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, erasing the lower address in the lower address memory, storing the lower address of the source MAC address of the packet in a duplicated use lower address memory, and sending the packet out to the front of the clockwise ring; On the other hand, when a packet from a base station outside the ring arrives at a device for adding, dropping, or passing the packet, if the destination MAC address of the packet is stored in the ring transmission line port address table, or if the device for adding, dropping, or passing the packet is in a steering state, a steering bit is added to the packet, If the packet is a packet immediately after the mobile terminal changes its destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, nothing is done; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, the lower address of the source MAC address of the packet is stored in lower address memory 7 which specifies packet transmission outside the ring, and the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, and the packet is sent forward to the front of the ring in a clockwise direction; On the other hand, if the packet is not a packet immediately after the mobile terminal changes the destination base station, If the lower address of the source MAC address of the packet is stored in the duplicated use lower address memory, do nothing; if the lower address of the source MAC address of the packet is not stored in the duplicated use lower address memory, store the lower address of the source MAC address of the packet in a lower address memory that specifies packet transmission outside the ring, and transmit the packet to the front of the ring in a clockwise direction; When the packet arrives at a packet add, drop and pass through device from the clockwise ring, if a lower address of the source MAC address of the packet is stored in a lower address memory that specifies packet transmission outside the ring, the lower address of the lower address memory is erased, the lower address of the source MAC address of the packet is stored in a duplicated use lower address memory, and the packet is sent to the front of the clockwise ring; When the packet arrives at a vertex device from the clockwise ring, store the lower address of the source MAC address of the packet in a lower address memory, and forward the packet to a server or switch via the router 22; When a packet from a server or an exchange arrives at a vertex device via a router 22, if the lower address of the destination MAC address of the packet is stored in a lower address memory, the packet is forwarded on a counterclockwise ring with a steering bit added, and if the lower address of the destination MAC address of the packet is not stored in the lower address memory, the packet is forwarded on a clockwise ring without a steering bit added.

10. The method of claim 8 or claim 9, further comprising:

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