Low-order address of transmission source mac address of ethernet frame, and handover method of mobile terminal using ring network to which ring node device is adopted to mac address storage method storing two bits 1 to storage area of memory to be accessed by intermediate address

Abstract

To realize a handover by transferring an Ethernet frame via a ring network.SOLUTION: In the case where a packet is arrived from a ring to an add of a packet, a drop, and a passed device, the case where only one of a first bit and a third bit is an initial storage bit, a bit 1 is stored to a fifth bit position if a storage area of an address position of a SRAM for a low-order address to be accessed in low-order address of a transmission source MAC address of the packet and an intermediate address designation memory. The bit 1 of an odd number of parity bits of the fifth bit is stored to a sixth bit. The bit 1 of a seventh bit position of the storage area of the address position of the SRAM to be accessed in the intermediate address of the transmission source MAC address of the packet is stored. The odd number of parity bits of the seventh bit is stored to an eighth bit position.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a handover method for a mobile terminal using a ring network that transfers Ethernet frames, in which a MAC address storage method for storing a bit 1 indicating lower address storage and a bit 1 indicating middle address storage in memory areas accessed by the lower address and the middle address of the source MAC address of an Ethernet (registered trademark) frame is applied to a ring node device. In the present invention, a packet that uses the MAC address portion of an Ethernet frame and an IPv6 address as the MAC address of a MAC packet is used.

[0002] As a conventional example of the address storage method, there is Japanese Patent Application Laid-Open No. 2000-151617, "Table Creation Search Device" of Patent Document 1. This conventional example relates to a memory circuit for a MAC address, and includes a first table composed of a RAM or the like having a row column address, a MAC address data area, and an index area, and a second table composed of a RAM or the like having a row column address, a MAC address data area, and an index area. In this conventional example, the entire 48-bit MAC address is stored at a designated position A in the memory of the first table in the lower bit string (for example, 16 bits). If another MAC address is already stored at the 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 the address position A of the first table. This is a method of designating a recording area by nesting.

[0003] Further, as a prior art of the address storage method, there is Japanese Patent Application Laid-Open No. 2004-15592 of Patent Document 2 There is a "MAC address pointer structure and method for rearranging MAC addresses". This conventional example is a method of storing a plurality of MAC addresses at the same address position in an entry table specified by a lower bit string. If there is no free area, the MAC address is stored in an entry table specified by a lower bit string different from the lower bit string of the MAC address.

[0004] As a conventional example of a ring network, a ring network using a master switch and slave switches as in Patent Document 3 is common. In this ring network, one ring port of the master switch is a block port that does not pass frames, preventing congestion due to flooding. When a failure occurs in the ring network, the monitoring frame that goes out from the master switch and returns to the master switch does not reach, and instead, a failure notification frame arrives at the master switch from the slave switch at the failure point. Therefore, the master switch releases the block of the block port of the master switch and passes the frame. Also, a block port is set on the failure transmission path side of one slave switch at the failure point to maintain the operation of the ring network even after the ring network recovers from the failure. One ring port of the switch becomes a block port that does not pass frames, preventing congestion due to flooding. When a failure occurs in the ring network, the monitoring frame that goes out from the master switch and returns to the master switch does not reach, and instead, a failure notification frame arrives at the master switch from the slave switch at the failure point. Therefore, the master switch releases the block of the block port of the master switch and passes the frame. Also, a block port is set on the failure transmission path side of one slave switch at the failure point to maintain the operation of the ring network even after the ring network recovers from the failure. Generally, in a conventional ring network, since a MAC address table is used in the ring node device, when a transmission path failure occurs, the FDB of all ring node devices in the ring is cleared, and the FDB is reconfigured by flooding.

[0005] As an example of a handover method, there is Patent Document 4. This prior art has an IPv6 connection via a base station and a gateway between a mobile terminal and an access router before switching, and an IPv6 connection via a target base station, and is a method of reducing the downtime of packets via the connection during connection switching.

[0006] As a fast handover for Mobile IPv6, there is Non-Patent Document 2. This is a method that uses FBU (Fast Biding Update) between the old access router and the mobile terminal to convey the CoA (care of address) to the Internet terminal and enable movement to the new access router.

[0007] As a mobile network to which handover is applied, there is Non-Patent Document 3. This is a network that uses a ring in the core network and distributes the home agent to each node of the ring.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0009]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] In the prior example of Japanese Patent Application Laid-Open No. 2000-151617 as a conventional address storage method, since the MAC address is stored by nesting, there is a problem that it sometimes takes time to trace the stored address using the storage address destination as an index.

[0011] Also, in the prior example of Japanese Patent Application Laid-Open No. 2004-15592 as a conventional address storage method, if there is no space in the entry table position of the MAC address specified by the lower bit column, it is described that the MAC address is stored in the entry table position of a different lower bit column. In that case, when selecting the position to store the MAC address, it is necessary to search the entry table positions specified by two lower bit columns, and since there are multiple non-consecutive lower storage addresses at the same intermediate address position in the same entry table, it is necessary to compare all of those multiple lower storage addresses, resulting in a problem that the search takes time.

[0012] Non-Patent Document 1 and Patent Document 3, which are conventional ring networks, store the destination MAC address of packets going to the left-handed ring, the destination MAC address of packets going to the right-handed ring, and the destination MAC address of packets sent out of the ring using the MAC address and port number. Therefore, there is a problem that the number of MAC addresses to be stored increases. Also, when the entire 48 bits of the MAC address are stored at the address position where memory is accessed using the lower address of the MAC address in the MAC address table, or when the upper address is stored, if the MAC address cannot be stored, when the destination MAC address of the transferred packet is not stored in the MAC address table (in the case of an unknown packet), there is a drawback that it is handled by flooding the packet.

[0013] Also, in a conventional ring network, when searching for a connection destination, the entire destination MAC address is required, and it is not possible to search using the lower address of the destination MAC address. 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 storing a lower address equal to the lower address of the source MAC address, since it is not known when the packet will arrive at the destination using the lower address of the destination MAC address, the above storage process cannot be performed. When the destination address is a fixed MAC address such as a server, it can be reached using the destination MAC address, but in the case of a terminal with many destinations, there is a problem that the device scale becomes large.

[0014] Also, in the conventional handover Patent Document 4, since two IPv4 or IPv6 connections are provided between the access router and the mobile terminal and switched, it is necessary to identify the two IP connections, and there is a drawback that the handover control becomes complicated.

[0015] Non-Patent Document 2 realizes handover by migrating the FBU from the old access router to the new access router. However, since a router is used for handover and waiting is performed at the router, there is a problem of a large delay time.

[0016] In addition, Non-Patent Document 3 disperses home agents to distribute the location registration load, but there is a problem that each home agent requires an IP prefix address. In the case of handover between base stations within a ring node, the IP prefix does not change. However, when changing the base station, it is necessary to change the IP prefix for the CoA (Care of Address), and there is a problem that it cannot be handled with only a 64-bit host address. When moving the ring node, the IP prefix naturally changes. Introducing IP addresses into the ring has the problem of making it impossible to transfer Ethernet frames within one domain by MAC addresses.

[0017] An object of the present invention is to show a method for realizing simple handover without using a conventional MAC address table by a ring network using a memory for storing the lower address and the middle address of the MAC address in 1 bit each in a ring node device.

Means for Solving the Problems

[0018] The present invention has been made in view of the problems of the above prior art, and the solution means are from the first aspect to the fifth aspect of the present invention shown below. A first aspect of the present invention is to insert devices for adding, dropping, and passing a plurality of packets into the ring network of the transmission path 2 of the clockwise ring and the transmission path 1 of the counterclockwise ring, connect an L2 switch and a base station to the devices for adding, dropping, and passing the packets, and the terminals and mobile terminals under the L2 switch and the base station respectively receive packets arriving from the counterclockwise ring of the ring network and transfer them to a router. When the source MAC address of the packet is the NIC MAC address of the ring network interface of the router, the function of blocking the passing of the packet when the source MAC address of the packet is stored in the MAC address table of the own device. For communicating with a destination server via the connected router on the vertex device on the ring network, the packets from the terminals and mobile terminals are respectively Ethernet frames of TCP, TCP, and UDP such as call signals between the router and the server across the ring network, and between the router and the server and between the router and the switch or the exchanger, IP packets are used to communicate with each other. When the packet from the mobile terminal arrives at the device for adding, dropping, and passing the packet of the ring network, regardless of whether the packet is a packet immediately after the mobile destination base station is changed or whether the packet is a communication start packet. Store a bit 1 in the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit in the second bit position, and store a bit 1 in the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the third bit in the fourth bit position. When only one of the first bit and the third bit is the first stored bit, store a bit 1 in the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the fifth bit in the sixth bit position, and store a bit 1 in the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the seventh bit in the eighth bit position. On one hand, when storing a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and middle address designation memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, if both the first bit and the third bit are the first stored bits, or if both bits are already stored, store a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and middle address designation memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the third bit at the fourth bit position, and send the packet to the counterclockwise ring. When the packet arrives at the device for adding, dropping, and passing the packet A bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designating memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position, or a bit 1 is stored at the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address designating memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the fifth bit is stored at the sixth bit position, and a bit 1 is stored at the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the seventh bit is stored at the eighth bit position. When the packet is a packet immediately after the destination base station is changed and is a packet for base station movement in the direction of packet transfer on the clockwise ring, the bit 1s of the first bit, the second bit, the third bit and the fourth bit or the fifth bit, the sixth bit, the seventh bit and the eighth bit are erased. On the other hand, when the packet is a packet immediately after the destination base station is changed and is not a packet for base station movement in the direction of packet transfer on the clockwise ring, the source MAC address of the packet is stored in the SRAM for the address table designating the passage of the packet, and the packet is directed to the ring node device in which the ring network interface NIC MAC address to which the server is connected via the router in the counterclockwise ring is stored as the destination MAC address of the packet. When a packet from the server is sent out to the clockwise ring from the ring node device in which the NIC MAC address of the router is stored as the source MAC address of the packet via the router and the packet arrives at the device for packet add, drop and pass. If the destination MAC address of the packet is stored in the SRAM for the address table that specifies the passage of the packet, the packet is sent forward to the right-handed ring. If the destination MAC address of the packet is not stored in the SRAM for the address table that specifies the passage of the packet, and the 5th bit position of the storage area of the SRAM address position for the lower address and the middle address specification memory accessed by the lower address of the destination MAC address of the packet stores a bit 1, the 6th bit position stores a bit 1 of the even parity bit of the 7th bit, and the 7th bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet stores a bit 1, and the 8th bit position stores a bit 1 of the even parity bit of the 7th bit, the packet is sent out of the ring. If the destination MAC address of the packet is not stored in the SRAM for the address table that specifies the passage of the packet, and the 1st bit position of the storage area of the SRAM address position for the lower address and the middle address specification memory accessed by the lower address of the destination MAC address of the packet stores a bit 1, the 2nd bit position stores a bit 1 of the even parity bit of the 1st bit, and the 3rd bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet stores a bit 1, and the 4th bit position stores a bit 1 of the even parity bit of the 3rd bit, the packet is sent out of the ring. Otherwise, the system is characterized by comprising means for sending the packet forward to the right-handed ring.

[0019] A second aspect of the present invention is in the system described in the first aspect of the present invention, the mobile terminal further has a step of periodically accessing a receiving mail server and, when it cannot receive a response packet from the receiving mail server, sending a retransmission packet to the receiving mail server.

[0020] A third aspect of the present invention is in the system described in the first aspect of the present invention, When the mobile terminal sends a packet immediately after moving from the target base station to the device for adding, dropping, and passing packets of the target base station in the ring network, it sends a pre-mobility preparation packet with the source MAC address of the packet as the destination MAC address in a clockwise ring. When the packet arrives at the device for adding, dropping, and passing packets, if a bit 1 is stored at the 5th bit position of the storage area of the SRAM address position for the lower address and the middle address specified memory accessed by the lower address of the destination MAC address of the packet, a bit 1 of the even parity bit of the 7th bit is stored at the 6th bit position, and a bit 1 is stored at the 7th bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 7th bit is stored at the 8th bit position, the packet is sent out of the ring. If the destination MAC address of the packet is not stored in the SRAM for the address table specifying packet passing, and a bit 1 is stored at the 1st bit position of the storage area of the SRAM address position for the lower address and the middle address specified memory accessed by the lower address of the destination MAC address of the packet, a bit 1 of the even parity bit of the 1st bit is stored at the 2nd bit position, and a bit 1 is stored at the 3rd bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 3rd bit is stored at the 4th bit position, the packet is sent out of the ring. Otherwise, the packet is sent forward in the clockwise ring. When the packet sent out of the ring arrives at the base station, if the destination MAC address of the packet is not stored in the MAC address table and a MAC address with the same lower address as the lower address of the destination MAC address of the packet is stored, a repaired packet with the stored MAC address as the source MAC address is sent in a counterclockwise ring from the device for adding, dropping, and passing packets of the packets belonging to the home base station. When the repaired packet arrives at the device for adding, dropping, and passing packets,A bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position, or a bit 1 is stored at the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the fifth bit is stored at the sixth bit position, and a bit 1 is stored at the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the seventh bit is stored at the eighth bit position. In this case, the system is characterized by comprising means for storing the source MAC address of the repair packet in the SRAM for the address table specifying the passage of the packet.

[0021] The fourth aspect of the present invention is to insert devices for adding, dropping, and passing a plurality of packets into the ring network of the transmission path 2 of the clockwise ring and the transmission path 1 of the counterclockwise ring, connect an L2 switch and a base station to the devices for adding, dropping, and passing the packets, and the terminals and mobile terminals under the L2 switch and the base station respectively receive the packets arriving from the counterclockwise ring of the ring network and transfer them to the router. When the source MAC address of the packet is stored in the MAC address table of the own device, the function of blocking the passing of the packet having the NIC MAC address of the ring network interface of the router as the source MAC address, and for communicating with the destination server via the connected router to the vertex device on the ring network, the packets from the terminals and mobile terminals are respectively Ethernet (registered trademark) frames of TCP, TCP, and UDP such as call signals between the router and the server across the ring network, and between the router and the server or switch, they are made to travel as IP packets, When the packet from the mobile terminal arrives at the device for adding, dropping, and passing the packets of the ring network, regardless of whether the packet is a packet immediately after changing the destination base station and regardless of whether the packet is a communication start packet, If a bit 1 is stored at the first bit position of the storage area of the SRAM address position for the lower address and the middle address specified memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position, and only one of the first bit and the third bit is the first stored bit, the source MAC address of the packet is stored in the packet drop address table, On one hand, when storing a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and middle address specifying memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, if both the first bit and the third bit are the first stored bits, or if both bits are already stored, store a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and middle address specifying memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and store a bit 1 of the even parity bit of the third bit at the fourth bit position, send the packet to the left - handed ring, when the packet arrives at the packet add, drop, and pass device, if the source MAC address of the packet is stored in the packet drop address table, erase the MAC address, A bit 1 is stored at the first bit position of a storage area of an SRAM address position for a lower address and an intermediate address designation memory accessed by a lower address of the source MAC address of the packet, a bit 1 of an even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the SRAM address position accessed by the intermediate address of the source MAC address of the packet, and when a bit 1 of the fourth bit position stores a bit 1 of an even parity bit of the third bit, if the packet is a packet immediately after the destination base station is changed, and is a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the bits 1 of the first bit, the second bit, the third bit, and the fourth bit are erased. On the other hand, if the packet is a packet immediately after the destination base station is changed and is not a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the source MAC address of the packet is stored in an SRAM for an address table designating passage of the packet, and the packet is directed to a ring node device in which the ring network interface NIC MAC address to which the server is connected via a router in a counterclockwise ring stores the destination MAC address of the packet as the destination MAC address of the packet, When a packet from a server is sent out to a clockwise ring from a ring node device in which the NIC MAC address of the router stores the source MAC address of the packet via the router, and the packet arrives at a device for adding, dropping, and passing the packet, When the destination MAC address of the packet is stored in the SRAM for the address table that specifies the passage of the packet, the packet is sent forward to the right-handed ring. When the destination MAC address of the packet is stored in the packet drop address table, the packet is sent out of the ring. When the destination MAC address of the packet is not stored in the SRAM for the address table that specifies the passage of the packet, and the destination MAC address of the packet is not stored in the packet drop address table, and bit 1 is stored at the first bit position of the storage area of the SRAM address position for the lower address and middle address specifying memory accessed by the lower address of the destination MAC address of the packet, and bit 1 of the even parity bit of the first bit is stored at the second bit position, and bit 1 is stored at the third bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet, and bit 1 of the even parity bit of the third bit is stored at the fourth bit position, the packet is sent out of the ring. Otherwise, the method includes the step of sending the packet forward to the right-handed ring.

[0022] A fifth aspect of the present invention is, in the method described in the fourth aspect of the present invention, The mobile terminal further has a step of periodically accessing a receiving mail server and sending a retransmission packet to the receiving mail server when it cannot receive a response packet from the receiving mail server.

Advantages of the Invention

[0023] As described above, the present invention stores a bit 1 at the memory area position accessed by the lower address of the source MAC address and stores a bit 1 at the memory area position accessed by the middle address of the source MAC address. When storing both bits, it stores only when both bits are the first bit 1 to be stored or both bits are already stored. When only one of them is already stored, it stores both bits at different bit positions in the data storage area. Therefore, it has the effect of reducing the number of stored MAC addresses required in the address table for specifying the passage of packets. In addition, in the present invention, since the ring node device (a device for adding, dropping, and passing packets) can be realized with two SRAMs, it has the effect of reducing the system cost. Further, the present invention is a method for realizing handover of a mobile terminal within a 1 MAC domain by a ring network using the above memory, which can suppress power consumption and system cost and has the effect of enabling high-speed communication.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0025] A first embodiment of the present invention will be described with reference to FIG. 1. In this embodiment, a packet add, drop, and pass device having an SRAM for a lower address and an intermediate address specification memory for specifying packet transmission outside the ring and an address table for specifying packet passage is connected to a packet add, drop, and pass device of a dual-ring network connected by a plurality of optical transmission paths by a base station. A mobile terminal under the base station transfers information as a MAC packet to a router connected to the ring network, and this is an example of a handover operation of a TCP packet or a voice packet of a mobile terminal using the ring network in a packet transfer system between the mobile terminal and a server connected to the ring network via the router. The server is a mail reception server or an Internet connection server.

[0026] In FIG. 1, 1 is the optical transmission path of the counterclockwise ring, 2 is the optical transmission path of the clockwise ring, 5 is the vertex device, 6-1, 6-2, 6-3 are the add, drop, and pass devices of the packet (ring node device), 8 is the address table for specifying the passage of the packet, 11 is the SRAM for the lower address and the intermediate address specifying memory for specifying the packet transmission outside the ring, 13-1, 13-2, 13-3, 13-4 are mobile terminals, 14-1, 14-2, 14-3 are base stations (BS), 20 is a server, 22 is a router, 26 is a switch, and 27 is a home memory. Also, (1) to (31) indicate the transfer order of the packets in which the MAC addresses transferred through the rings indicated by the dotted lead lines are abbreviated with character symbols, and I0, I1, I2, I3, I4 are the global IPv4 addresses for which the dynamic IP addresses are set in the terminals, or the domestic IPv4 addresses of the service providers. Or they are IPv6 addresses. The OE conversion circuit, the EO conversion circuit, etc., and the input buffer and the output buffer are not shown in the figure.

[0027] The operation of FIG. 1 will be described below. An example is shown in which the mobile terminal 13-2 for mail transmission sends a packet (1) Mn2γβα(I7) (where M indicates an Ethernet packet, n2 is the wireless MAC address of the base station 14-2, γβα indicates the upper MAC address γ, the intermediate MAC address β, and the lower MAC address α of the mobile terminal 13-2, and I7 indicates the IP address of the switch 26 which is the destination) to the base station 14-2. When the Ethernet frame (2) Mr1r2γβα(I7) (r1r2 indicates the NIC MAC address of the ring network interface of the router 22) reaches the packet add, drop, and pass device 6-2 from the terminal 13-2, since the MAC address ηγα of the mobile terminal 13-4 is stored in the packet add, drop, and pass device 6-2, the bit 1 is already stored in the 1st bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designating memory that designates packet transmission to the outside of the ring accessed by the lower address α (for example, from the 1st bit to the 17th bit) of the source MAC address of the packet. Since the bit 1 is not stored in the 3rd bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designating memory that designates packet transmission to the outside of the ring accessed by the intermediate address β (for example, taking from the 18th bit to the 34th bit as from the 1st bit to the 17th bit of the memory) of the source MAC address of the packet, the bit 1 is stored in the 5th bit position of the storage area of the address position of the SRAM for the lower address and intermediate address designating memory accessed by the lower address α of the source MAC address of the packet, the bit 1 of the even parity bit of the 5th bit is stored in the 6th bit position, and the bit 1 is stored in the 7th bit position of the storage area of the address position of the SRAM accessed by the intermediate address β of the source MAC address of the packet, and the bit 1 of the even parity bit of the 7th bit is stored in the 8th bit position, The packet is sent toward the address table 12 of the vertex device 5 in which the NIC MAC address of the upper ring network interface of the router 22 connected to the server 20 is stored by the current optical transmission path 1 of the counterclockwise ring. In the figure, the storage of bits in the lower address and the middle address specifying memory for specifying packet transmission outside the ring is shown as two-stage storage of 8 bits from the first bit from the left to the last 8th bit. The vertical lines to the right of α, η, and β indicate the access addresses to the memory, and the storage bit 1 and the parity bit 1 are written to the right of the vertical lines.

[0028] The packet is sent toward the vertex device 5 in the counterclockwise ring 1. When the packet arrives at the vertex device 5, since the destination MAC address r1r2 of the packet is stored in the address table 12 for the router, the packet is dropped from the ring toward the router 22 outside the ring as (5)Mr1r2γβα(I7). When the packet arrives at the router 22, the source MAC address (γβα) and the IP address (I3) of the packet are stored in the ARP table not shown in the figure, or the source MAC address (γβα) is put into the option area of the IP header, and the IP packet is transferred as (6)IPI3I7 (where IP indicates the IP address, I3 indicates the IP address of the mobile terminal 13-2, and I7 indicates the IP address of the switch 26 as the destination.) as shown in the figure to reach the server 20.

[0029] Next, when the mobile terminal 13-1 receiving the mail reception service sends a packet (7) Mr1r2δβα(I0) (where M indicates an Ethernet packet, r1r2 indicates the NIC MAC address of the ring network interface of the router 22, δβα indicates the upper MAC address δ, the middle MAC address β, and the lower MAC address α of the MAC address of the terminal device 13-1, and I0 indicates the IP address of the destination server) to the packet add, drop, and pass device 6-1 via the base station 14-1, a bit 1 is stored in the first bit position of the storage area of the SRAM for the lower address and middle address designated memory accessed by the lower address of the source MAC address of the packet, and a bit 1 of the even parity bit of the first bit is stored in the second bit position. Also, when a bit 1 is stored in the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored in the fourth bit position, if only one of the first bit and the third bit is the first stored bit, a bit 1 is stored in the fifth bit position of the storage area of the SRAM address position for the lower address and middle address designated memory accessed by the lower address of the source MAC address of the packet, and a bit 1 of the even parity bit of the fifth bit is stored in the sixth bit position. Also, a bit 1 is stored in the seventh bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the seventh bit is stored in the eighth bit position. On one hand, when storing a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and the middle address specifying memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, if both the first bit and the third bit are the first stored bits, or if both bits are already stored, store a bit 1 at the first bit position of the storage area of the SRAM address position for the lower address and the middle address specifying memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and store a bit 1 of the even parity bit of the third bit at the fourth bit position. In the figure, it is an example of the first storage of the first bit and the third bit. The packet is sent towards the address table 12 in which the NIC MAC address of the ring network interface of the router 22 connected to the server 20 by the current optical transmission path 1 of the counterclockwise ring is stored.

[0030] When the packet is transferred to the counterclockwise ring 1 as shown in the figure by (9)Mr1r2δβα(I0) and arrives at the packet add, drop, and pass device 6-2, the lower address α of the source MAC address of the packet (for example, from the 1st bit to the 17th bit) accesses the storage area of the address position of the SRAM (11) for the lower address and intermediate address designation memory that designates the packet transmission out of the ring. The 1st bit of the 1st bit position of the storage area has bit 1 already stored. The 3rd bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designation memory that designates the packet transmission out of the ring accessed by the intermediate address β of the source MAC address of the packet (for example, from the 18th bit to the 34th bit as from the 1st bit to the 17th bit of the memory) does not have bit 1 stored. The 5th bit position of the storage area of the address position of the SRAM for the lower address and intermediate address designation memory accessed by the lower address α of the source MAC address of the packet has bit 1 stored, the 6th bit position has bit 1 of the even parity bit of the 5th bit stored, and the 7th bit position of the storage area of the address position of the SRAM accessed by the intermediate address β of the source MAC address of the packet has bit 1 stored, and the 8th bit position has bit 1 of the even parity bit of the 7th bit stored. Therefore, the source MAC address δβα of the packet is stored in the address table 8 that designates the packet passing. When the destination MAC address r1r2 of the packet arrives at the vertex device 5 where it is stored in the address table 12 for the router, the packet is dropped from the ring as (12)Mr1r2δβα(I0) toward the router 22 outside the ring. When the packet arrives at the router 22, the source MAC address (δβα) and IP address (I2) of the packet are stored in an ARP table (not shown in the figure), or the source MAC address (δβα) is put into the option area of the IP header, and the IP packet is transferred as (13)IPI2I0 (where IP indicates that it is an IP address, I2 is the IP address of the mobile terminal 13-1, and I0 is the IP address of the destination server 20) as shown in the figure to reach the server 20.

[0031] Next, an example is shown when the mobile terminal 13-2 moves from the base station 14-2 under the jurisdiction of the base station 14-1. Immediately before the mobile terminal 13-2 accesses the destination base station 14-1, the mobile terminal 13-2 sends a MAC address authentication packet transmission request packet (14)Mn2γβα() to the source base station 14-2. The source base station 14-2 checks the MAC address of the mobile terminal 13-2 in the MAC address table (not shown in the figure) and sends the MAC address authentication packet (15)MB1γβα() of the mobile terminal 13-2 to the destination base station 14-1. When the MAC address authentication packet arrives at the device 6-2 for packet add, drop, and pass, the packet is sent to the destination base station 14-1. When a packet (18)Mn1γβα(I7) from the mobile terminal 13-2 (where n1 indicates the wireless NIC MAC address of the base station 14-1, and γβα indicates the MAC address of the mobile terminal 13-2 (upper address γ, middle address β, lower address α)) arrives at the base station 14-1, there is a packet immediately after the change of the destination base station when the device 6-1 for adding, dropping, and passing the connected packets of the said destination base station is a device that connects to the base station in the direction away from the server 20 on the counterclockwise ring 1. However, that packet is sent as (19)Mr1r2γβα(I7) to the device 6-1 for adding, dropping, and passing the packet. When a packet (18)Mn1γβα(I7) from the mobile terminal 13-2 (where n1 indicates the wireless NIC MAC address of the base station 14-1, and γβα indicates the MAC address of the mobile terminal 13-2 (upper address γ, middle address β, lower address α)) arrives at the base station 14-1, there is a packet immediately after the change of the destination base station when the device 6-1 for adding, dropping, and passing the connected packets of the said destination base station is a device that connects to the base station in the direction away from the server 20 on the counterclockwise ring 1. However, that packet is sent as (19)Mr1r2γβα(I7) to the device 6-1 for adding, dropping, and passing the packet.When the packet from the mobile terminal 13-2 reaches the add, drop, and pass device 6-1, store bit 1 in the first bit of the storage area of the address position of the SRAM (11) for the lower address and middle address specifying memory that designates packet transmission to the outside of the ring accessed by the lower address α of the source MAC address of the packet, store bit 1 in the second bit as the even parity of the first bit, store bit 1 in the third bit of the storage area of the address position of the SRAM (11) for the lower address and middle address specifying memory that designates packet transmission to the outside of the ring accessed by the middle address β of the source MAC address of the packet, and store bit 1 in the fourth bit as the even parity of the third bit. If only one of the first bit and the third bit is the first stored bit, store bit 1 in the fifth bit position of the storage area of the address position of the SRAM for the lower address and middle address specifying memory accessed by the lower address of the source MAC address of the packet, store bit 1 of the even parity bit of the fifth bit in the sixth bit position, store bit 1 in the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and store bit 1 of the even parity bit of the seventh bit in the eighth bit position. However, in this case, since the lower address α and the middle address β of the MAC address of the mobile terminal 13-1 have already been stored,... Store bit 1 in the first bit position of the storage area of the address position of the SRAM for the lower address and middle address specifying memory accessed by the lower address of the source MAC address of the packet, store bit 1 of the even parity bit of the first bit in the second bit position, store bit 1 in the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and store bit 1 of the even parity bit of the third bit in the fourth bit position. Send it to the address table 12 of the vertex device 5 where the NIC MAC address of the upper ring network interface of the router 22 that connects the packet to the server 20 through the current optical transmission path 1 of the counterclockwise ring is stored.

[0032] When the packet is transferred to the counterclockwise ring 1 as shown in the figure by (20) Mr1r2γβα (I7) and arrives at the packet adding, dropping, and passing device 6-2, the lower address for designating packet transmission to the outside of the ring accessed by the lower address α of the source MAC address of the packet (for example, from the 1st bit to the 17th bit) and the storage area of the address position of the SRAM (11) for the lower address and intermediate address designating memory, bit 1 is already stored in the 1st bit. For the storage area of the address position of the SRAM (11) for the lower address and intermediate address designating memory accessed by the intermediate address β of the source MAC address of the packet (for example, taking the 18th bit to the 34th bit as the 1st bit to the 17th bit of the memory), bit 1 is not stored in the 3rd bit. Bit 1 is stored in the 5th bit position of the storage area of the address position of the SRAM for the lower address and intermediate address designating memory accessed by the lower address α of the source MAC address of the packet, and bit 1 is stored in the 7th bit position of the storage area of the address position of the SRAM accessed by the intermediate address β of the source MAC address of the packet. The packet is a packet immediately after the transfer destination base station is changed and is a packet moving to the base station in the clockwise ring packet transfer direction, so the 5th bit and the 7th bit are erased. The fact that the bits are erased is shown by a horizontal line in the figure. When the packet arrives at the vertex device 5 in the counterclockwise ring 1, since the destination MAC address r1r2 of the packet is stored in the address table 12 for the router, the packet is dropped from the ring as (23) Mr1r2γβα (I7) toward the router 22 outside the ring and goes to the router 22.

[0033] When the packet arrives at router 22, the source MAC address (γβα) and IP address (I3) of the packet are stored in an ARP table not shown in the figure, or the source MAC address (γβα) is put into the option area of the IP header, and the IP packet is transferred as (24)IPI3I7 (where IP indicates that it is an IP address, I3 is the IP address of the terminal connected to terminal device 13-2, and I7 is the IP address of switch 26 which is the destination.) as shown in the figure and reaches switch 26.

[0034] Next, when a packet (25)IPI7I3 from switch 26 (where IP indicates that it is an IP address, I3 is the IPv6 address or IPv4 address of terminal device 13-2, and I7 is the IP address of switch 26) arrives at router 22, if the packet is an IPv6 address, the destination MAC address corresponding to the destination IPv6 address I3 of the packet is copied from the MAC address part of the destination IPv6 address and used as the MAC header address of the MAC packet (26)Mγβαr1r2(I3), and the MAC packet is sent to vertex device 5 of the ring network. If the packet is an IPv4 address, the destination MAC address γβα corresponding to the destination IP address I3 of the packet is obtained from an ARP table not shown in the figure, used as the destination MAC header address of the MAC packet, or the MAC address γβα in the option area of the IP header is used as the destination MAC address, and a MAC packet (26)Mγβαr1r2(I3) with the source MAC address being the NIC MAC address r1r2 of the ring network interface of router 22 is sent to vertex device 5 of the ring network.

[0035] When the MAC packet (26)Mγβαr1r2(I3) arrives at vertex device 5, since the source MAC address of the packet is stored in address table 12 for router connection, the packet is sent to the right - hand ring 2.

[0036] When the packet (28) Mγβαr1r2 (I3) is transferred to the right - hand ring 2 and arrives at the device 6 - 2 for packet add, drop, and pass, if the destination MAC address γβα of the packet is not stored in the address table 8 that specifies packet passing, and bit 1 is stored in the first bit of the storage area of the address position of the SRAM (11) for the lower - address memory that specifies packet transmission outside the ring accessed by the lower - address α of the destination MAC address of the packet, and as the even parity of the first bit, bit 1 is stored in the second bit, and bit 1 is not stored in the third bit of the storage area of the address position of the SRAM (11) for the lower - address memory that specifies packet transmission outside the ring accessed by the middle - address β of the destination MAC address of the packet, and as the even parity of the third bit, bit 1 is not stored in the fourth bit, and bit 1 is not stored in the fifth bit of the storage area of the address position of the SRAM (11) for the lower - address memory that specifies packet transmission outside the ring accessed by the lower - address α of the destination MAC address of the packet, and bit 1 is not stored in the seventh bit of the storage area of the address position of the SRAM (11) for the lower - address memory that specifies packet transmission outside the ring accessed by the middle - address β of the destination MAC address of the packet, the packet is sent to the right - hand ring.

[0037] When the packet (29) Mγβαr1r2 (I3) is transferred through the clockwise ring 2 and arrives at the packet add, drop, and pass device 6-1, if the destination MAC address γβα of the packet is not stored in the address table 8 that specifies packet passing, and the first bit in the storage area of the address position of the SRAM (11) for the lower address and middle address specifying memory that designates packet transmission outside the ring accessed by the lower address α of the destination MAC address of the packet stores bit 1, and as the even parity of the first bit, bit 1 is stored in the second bit, and the third bit in the storage area of the address position of the SRAM (11) for the lower address and middle address specifying memory that designates packet transmission outside the ring accessed by the middle address β of the destination MAC address of the packet stores bit 1, and as the even parity of the third bit, bit 1 is stored in the fourth bit, the packet is transmitted outside the ring. When the packet arrives at the base station 14-1, since the destination MAC address of the packet is stored in the MAC address table not shown in the figure, the packet heads towards the destination mobile terminal 13-2.

[0038] Next, a second embodiment of the present invention will be described with reference to FIG. 2. In this embodiment, a packet add, drop, and pass device having an SRAM for the lower address and middle address specifying memory that designates packet transmission outside the ring, a packet drop address table, and an address table that specifies packet passing is connected by an optical transmission line in a plurality, and a base station is connected to the packet add, drop, and pass device of the dual ring network. Mobile terminals under the base station transfer information as MAC packets to a router connected to the ring network, and this is an example of a handover operation of TCP packets or voice packets of a mobile terminal using the ring network in a packet transfer system between the router and a server connected to the ring network. The server is a mail receiving server or an Internet connection server.

[0039] In FIG. 2, 1 is the optical transmission path of the counterclockwise ring, 2 is the optical transmission path of the clockwise ring, 5 is the vertex device, 6-1, 6-2, 6-3 are the devices for adding, dropping, and passing packets (ring node devices), 8 is the address table for specifying the passage of packets, 11 is the SRAM for the lower address and the intermediate address specifying memory for specifying the packet transmission outside the ring, 12 is the packet drop address table, 13-1, 13-2, 13-3, 13-4 are mobile terminals, 14-1, 14-2, 14-3 are base stations (BS), 20 is a server, 22 is a router, 25-1 is the address table for router connection, 26 is a switch, and 27 is the home memory. Also, (1) to (31) indicate the transfer order of the packets in which the MAC addresses transferred through the rings indicated by the dotted lead lines are abbreviated with character symbols, and I0, I1, I2, I3, I4 are the global IPv4 addresses set with dynamic IP addresses for the terminals, or the domestic IPv4 addresses of the service providers. Or they are IPv6 addresses. The OE conversion circuit, the EO conversion circuit, etc., and the input buffer and the output buffer are not shown in the figure.

[0040] The operation of FIG. 2 will be described below. An example is shown in which a mobile terminal 13-2 for mail transmission sends a packet (1) Mn2γβα(I7) (where M indicates an Ethernet packet, n2 is the wireless MAC address of the base station 14-2, γβα indicates the upper MAC address γ, the intermediate MAC address β, and the lower MAC address α of the mobile terminal 13-2, and I7 indicates the IP address of the switch 26 which is the destination) to the base station 14-2. When the Ethernet frame (2) Mr1r2γβα(I7) (r1r2 indicates the NIC MAC address of the ring network interface of the router 22) reaches the packet add, drop, and pass device 6-2 from the terminal 13-2, since the MAC address γηα of the mobile terminal 13-4 is stored in the packet add, drop, and pass device 6-2, the bit 1 is already stored in the 1st bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designation memory that designates packet transmission outside the ring accessed by the lower address α (for example, from the 1st bit to the 17th bit) of the source MAC address of the packet, and the bit 1 is stored in the 3rd bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designation memory that designates packet transmission outside the ring accessed by the intermediate address η (for example, taking the 18th bit to the 34th bit as the 1st bit to the 17th bit of the memory) of the source MAC address of the packet. However, since the bit 1 is not stored in the 3rd bit of the storage area of the address position of the SRAM (11) for the lower address and intermediate address designation memory that designates packet transmission outside the ring accessed by the intermediate address β (for example, taking the 18th bit to the 34th bit as the 1st bit to the 17th bit of the memory) of the source MAC address of the packet, the source MAC address of the packet is stored in the packet drop address table 12, The packet is sent towards the address table 12 of the vertex device 5 in which the NIC MAC address of the upper ring network interface of the router 22 connected to the server 20 is stored by the current optical transmission path 1 of the counterclockwise ring. In the figure, the storage of bits in the lower address and the middle address specifying memory for specifying packet transmission outside the ring is shown as two-stage storage of 4 bits from the first bit from the left to the last fourth bit. The vertical lines to the right of α, η, and β indicate the access addresses to the memory, and the stored bit 1 and the parity bit 1 are written to the right of the vertical lines.

[0041] The packet is sent towards the vertex device 5 on the counterclockwise ring 1. When the packet arrives at the vertex device 5, since the destination MAC address r1r2 of the packet is stored in the address table 12 for the router, the packet drops from the ring towards the router 22 outside the ring as (5)Mr1r2γβα(I7). When the packet arrives at the router 22, the source MAC address (γβα) and the IP address (I3) of the packet are stored in the ARP table not shown in the figure, or the source MAC address (γβα) is put into the option area of the IP header, and the IP packet is transferred as (6)IPI3I7 (where IP indicates the IP address, I3 indicates the IP address of the mobile terminal 13-2, and I7 indicates the IP address of the destination switch 26) as shown in the figure to reach the server 20.

[0042] Next, when the mobile terminal 13-1 receiving the mail reception service sends a packet (7) Mr1r2δβα(I0) (where M indicates an Ethernet packet, r1r2 indicates the NIC MAC address of the ring network interface of the router 22, δβα indicates the upper MAC address δ, the middle MAC address β, and the lower MAC address α of the MAC address of the terminal device 13-1, and I0 indicates the IP address of the destination server) to the packet add, drop, and pass device 6-1 via the base station 14-1, a bit 1 is stored in the first bit position of the storage area of the SRAM for the lower address and the middle address designated memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored in the second bit position, and a bit 1 is stored in the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored in the fourth bit position. If only one of the first bit and the third bit is the first stored bit, the source MAC address of the packet is stored in the packet drop address table 12. In the figure, when a bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position. Since both the first bit and the third bit are either the first stored bits or both bits are already stored, a bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position. In the figure, it is an example of the first storage of the first bit and the third bit as bit 1. The packet is sent toward the address table 12 in which the NIC MAC address of the ring network interface of the router 22 connected to the server 20 by the current optical transmission path 1 of the counterclockwise ring is stored.

[0043] When the packet is transferred counterclockwise through Ring 1 as shown in the figure by (9)Mr1r2δβα(I0) and arrives at the packet add, drop, and pass device 6-2, if the least significant address α of the source MAC address of the packet (e.g., from the 1st bit to the 17th bit) accesses the storage area of the address position of the SRAM (11) for the least significant address and intermediate address specification memory that designates packet transmission out of the ring, bit 1 is already stored in the 1st bit. If the intermediate address β of the source MAC address of the packet (e.g., taking bits 18th to 34th as bits 1st to 17th of the memory) accesses the storage area of the address position of the SRAM (11) for the least significant address and intermediate address specification memory that designates packet transmission out of the ring, bit 1 is not stored in the 3rd bit. Since the source MAC address of the packet is not stored in the packet drop address table 12, the packet is directly sent to the counterclockwise ring. When the destination MAC address r1r2 of the packet arrives at the vertex device 5 stored in the address table 12 for the router, the packet drops from the ring towards the router 22 outside the ring as (12)Mr1r2δβα(I0). When the packet arrives at the router 22, the source MAC address (δβα) and the IP address (I2) of the packet are stored in the ARP table not shown in the figure, or the source MAC address (δβα) is put into the option area of the IP header, and the IP packet is transferred as shown in the figure by (13)IPI2I0 (where IP indicates the IP address, I2 is the IP address of the mobile terminal 13-1, and I0 is the IP address of the destination server 20) to reach the server 20.

[0044] Next, an example is shown when the mobile terminal 13-2 moves under the jurisdiction of the base station 14-1 from the base station 14-2. Just before the mobile terminal 13-2 accesses the destination base station 14-1, the source base station 14-2 sends a MAC address authentication packet transmission request packet (14) Mn2γβα() of the mobile terminal 13-2. The source base station 14-2 checks the MAC address of the mobile terminal 13-2 in a MAC address table (not shown in the figure) and sends a MAC address authentication packet (15) MB1γβα() of the mobile terminal 13-2 to the destination base station 14-1. When the MAC address authentication packet arrives at the packet add, drop, and pass device 6-2, the packet is sent to the destination base station 14-1. When a packet (18)Mn1γβα(I7) from the mobile terminal 13-2 (where n1 indicates the wireless NIC MAC address of the base station 14-1 and γβα indicates the MAC address of the mobile terminal 13-2 (upper address γ, middle address β, lower address α)) arrives at the base station 14-1, there is a packet immediately after the change of the destination base station when the device 6-1 for adding, dropping, and passing the packets connected to the said destination base station is a device that connects to the base station in the direction away from the server 20 on the counterclockwise ring 1. However, this packet is sent as (19)Mr1r2γβα(I7) to the device 6-1 for adding, dropping, and passing the packets. When the said packet from the mobile terminal 13-2 reaches the device 6-1 for adding, dropping, and passing the packets, store bit 1 in the first bit of the storage area of the address position of the SRAM (11) for the lower address and middle address designating memory that designates the packet transmission to the outside of the ring accessed by the lower address α of the source MAC address of the said packet, store bit 1 in the second bit as the even parity of the first bit, store bit 1 in the third bit of the storage area of the address position of the SRAM (11) for the lower address and middle address designating memory that designates the packet transmission to the outside of the ring accessed by the middle address β of the source MAC address of the said packet, and store bit 1 in the fourth bit as the even parity of the third bit. If only one of the first bit and the third bit is the first stored bit, store the source MAC address of the said packet in the packet drop address table 12. In this case, since the lower address α and the middle address β of the MAC address of the mobile terminal 13-1 are already stored, Store a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address specifying memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and store a bit 1 of the even parity bit of the third bit at the fourth bit position. Send it to the address table 12 of the vertex device 5 in which the NIC MAC address of the upper ring network interface of the router 22 that connects the packet to the server 20 through the current optical transmission path 1 of the counterclockwise ring is stored.

[0045] When the packet is transferred through the counterclockwise ring 1 as shown in the figure by (20)Mr1r2γβα(I7) and arrives at the packet add, drop and pass device 6-2, a bit 1 is already stored at the first bit of the storage area of the address position of the SRAM (11) for the lower address and the middle address specifying memory that designates packet transmission to the outside of the ring accessed by the lower address α (for example, from the first bit to the 17th bit) of the source MAC address of the packet. Since the bit 1 is not stored at the third bit of the storage area of the address position of the SRAM (11) for the lower address and the middle address specifying memory that designates packet transmission to the outside of the ring accessed by the middle address β (for example, taking the 18th bit to the 34th bit as the 1st bit to the 17th bit of the memory) of the source MAC address of the packet, and the source MAC address of the packet is stored in the packet drop address table 2, the stored MAC address γβα is erased. The fact that γβα is erased is shown by a horizontal line in the figure. When the packet arrives at the vertex device 5 in the counterclockwise ring 1, since the destination MAC address r1r2 of the packet is stored in the address table 12 for the router, the packet is dropped from the ring as (23)Mr1r2γβα(I7) toward the router 22 outside the ring and heads for the router 22.

[0046] When the packet arrives at router 22, the source MAC address (γβα) and IP address (I3) of the packet are stored in an ARP table (not shown in the figure), or the source MAC address (γβα) is placed in the option field of the IP header, and the IP packet is transferred as shown in the figure by (24) IPI3I7 (where IP indicates that it is an IP address, I3 is the IP address of the terminal connected to terminal device 13-2, and I7 is the IP address of switch 26 which is the destination) and reaches switch 26.

[0047] Next, when a packet (25) IPI7I3 from switch 26 (where IP indicates that it is an IP address, I3 is the IPv6 address or IPv4 address of terminal device 13-2, and I7 is the IP address of switch 26) arrives at router 22, if the packet is an IPv6 address, the destination MAC address corresponding to the destination IPv6 address I3 of the packet is copied from the MAC address part of the destination IPv6 address and used as the MAC header address of the MAC packet (26) Mγβαr1r2(I3), and the MAC packet is sent to vertex device 5 of the ring network. If the packet is an IPv4 address, the destination MAC address γβα corresponding to the destination IP address I3 of the packet is obtained from an ARP table (not shown in the figure), used as the destination MAC header address of the MAC packet, or the MAC address γβα in the option field of the IP header is used as the destination MAC address, and the source MAC address is set to the NIC MAC address r1r2 of the ring network interface of router 22, and the MAC packet (26) Mγβαr1r2(I3) is sent to vertex device 5 of the ring network.

[0048] When the MAC packet (26) Mγβαr1r2(I3) arrives at vertex device 5, since the source MAC address of the packet is stored in address table 12 for router connection, the packet is sent to right - hand ring 2.

[0049] When the packet (28) Mγβαr1r2 (I3) is transferred to the clockwise ring 2 and arrives at the device 6-2 for adding, dropping, and passing the packet, if the destination MAC address γβα of the packet is not stored in the address table 8 that specifies the passing of the packet, and the first bit of the storage area of the address position of the SRAM (11) for the lower address memory that specifies the packet transmission to the outside of the ring accessed by the lower address α of the destination MAC address of the packet stores bit 1, and as the even parity of the first bit, bit 1 is stored in the second bit, and the third bit of the storage area of the address position of the SRAM (11) for the lower address memory that specifies the packet transmission to the outside of the ring accessed by the middle address β of the destination MAC address of the packet does not store bit 1, and as the even parity of the third bit, bit 1 is not stored in the fourth bit, and since the destination MAC address of the packet is not stored in the packet drop address table 12, the packet is sent to the clockwise ring.

[0050] When the packet (29) Mγβαr1r2 (I3) is transferred through the clockwise ring 2 and arrives at the packet add, drop, and pass device 6-1, if the destination MAC address γβα of the packet is not stored in the address table 8 that designates packet passing, and bit 1 is stored in the first bit of the storage area of the address position of the SRAM (11) for the lower address and middle address designation memory that designates packet transmission outside the ring accessed by the lower address α of the destination MAC address of the packet, and as the even parity of the first bit, bit 1 is stored in the second bit, and bit 1 is stored in the third bit of the storage area of the address position of the SRAM (11) for the lower address and middle address designation memory that designates packet transmission outside the ring accessed by the middle address β of the destination MAC address of the packet, and as the even parity of the third bit, bit 1 is stored in the fourth bit, the packet is transmitted outside the ring. When the packet arrives at the base station 14-1, since the destination MAC address of the packet is stored in the MAC address table not shown in the figure, the packet goes toward the destination mobile terminal 13-2.

[0051] Note that in Example 1, by separating the memory accessed by the lower address and the memory accessed by the middle address, it is also possible to simultaneously perform access by the lower address and access by the middle address to improve the operation speed.

[0052] In Embodiment 1, when a bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet to be added to the ring node device, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, if only one of them is the first stored bit, a bit 1 is stored at the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, and a bit 1 is stored at the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet. On the other hand, when a bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, if both are the first stored bits, or if both bits are already stored, the number of stored MAC addresses in the address table that designates the passing of the packet in the ring node device that stores a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, and stores a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet becomes an issue.Incidentally, when stored in the first bit and the third bit, the number of packet terminals to be added to the ring is 10,000, the number of terminals to be transferred on the ring is 100,000, the number of address specification bits of the SRAM is 17 bits, and the number of numbers for identifying the NIC manufacturing manufacturers of the mobile terminals is 128 (7 bits), the number of stored MAC addresses N in the address table for specifying the passage of the packet is N = 10,000 * 100,000 / EXP((24 + 7 - 17)ln2) / EXP(17ln2) = 0.47. Since the number of MAC addresses stored in the fifth and seventh bits is small, the number of stored MAC addresses in the address table for specifying the passage of the packet by that is also small, and there is no problem in realizing Example 1. Note that instead of storing at the fifth and seventh bit positions, it may be stored in the packet drop address table. Also, when the number of numbers for identifying the NIC manufacturing manufacturers of the mobile terminals is small, the number of bits of the lower address and the middle address may be set to 16 or 15. Example 1 can be composed of only existing memories, so it is easy to introduce into the LAN.

[0053] In Examples 1 and 2, when the mobile terminal cannot receive the response packet of the periodic access packet to the receiving mail server of the mobile terminal, a retransmission packet is sent to the receiving mail server.

[0054] In the case of a ring failure in Example 1, it can be handled without flooding by steering or both ring loopbacks. When both ring loopbacks are performed, in the case of a ring network failure, loopback is performed at the add, drop, and pass devices of the packets on both sides of the failure point. When loopback is performed, a loopback bit is added. The packet with the loopback bit added passes through all the devices until the point of the second loopback, and the loopback bit is removed in the second loopback. In addition, steering can be easily achieved during the ring failure in the second embodiment. When a packet immediately after the mobile terminal changes to a destination base station in the second embodiment arrives at the packet add, drop, and pass device, if a bit 1 is stored at the first bit position of the storage area of the SRAM for the lower address and the middle address specified memory accessed by the lower address of the source MAC address of the packet, and a bit 1 is stored at the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and if a bit 1 is already stored at both bit positions, the source MAC address of the packet may be stored in the packet drop address table. The packet drop address table is a memory that stores the upper address and the middle address in the storage area accessed by the lower address. Since the number of MAC addresses to be stored is small, there is no case where it cannot be stored.

Explanation of Signs

[0055] 1 Optical transmission path of the counterclockwise ring 2 Optical transmission path of the clockwise ring 5 Vertex device 6-1,6-2,6-3 Packet add, drop, and pass device 8 Address table for specifying packet passing 11 SRAM for the lower address and the middle address specified memory for specifying packet transmission outside the ring 12 Address table for router connection 13-1,13-2,13-3,13-4 Terminal device 14-1,14-2,14-3 Base station (BS) 20 Server 22 Router 26 Switch

Claims

1. Insert devices for adding, dropping, and passing a plurality of packets into the ring network of the transmission path 2 of the clockwise ring and the transmission path 1 of the counterclockwise ring, connect an L2 switch and a base station to the devices for adding, dropping, and passing the packets, and the terminals and mobile terminals under the L2 switch and the base station respectively receive the packets arriving from the counterclockwise ring of the ring network and transfer them to the router; when the source MAC address of the packet is the NIC MAC address of the ring network interface of the router, block the passing of the packet if the source MAC address of the packet is stored in the MAC address table of the device itself. For the vertex device on the ring network to communicate with the destination server via the connected router, the packets from the terminals and mobile terminals are respectively Ethernet (registered trademark) frames of TCP, TCP, and UDP such as call signals between the router and the server across the ring network, and between the router and the server or switch, they are IP packets for communication. When the packet from the mobile terminal arrives at the device for adding, dropping, and passing the packets of the ring network, regardless of whether the packet is a packet immediately after the mobile destination base station is changed and regardless of whether the packet is a communication start packet. Store a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address specifying memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the third bit at the fourth bit position. When only one of the first bit and the third bit is the first stored bit, store a bit 1 at the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address specifying memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the fifth bit at the sixth bit position, and store a bit 1 at the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the seventh bit at the eighth bit position. On one hand, when storing a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, when both the first bit and the third bit are the first stored bits, or when both bits are already stored, store a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, store a bit 1 of the even parity bit of the first bit at the second bit position, and store a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, store a bit 1 of the even parity bit of the third bit at the fourth bit position, and send the packet to the left - hand ring, when the packet arrives at the device for packet add, drop, and pass, When a bit 1 is stored at the first bit position of a storage area of an address position of SRAM for a lower address and an intermediate address designation memory accessed by a lower address of a source MAC address of the packet, a bit 1 of an even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of a storage area of an address position of the SRAM accessed by an intermediate address of the source MAC address of the packet, and a bit 1 of an even parity bit of the third bit is stored at the fourth bit position, or when a bit 1 is stored at the fifth bit position of a storage area of an address position of SRAM for a lower address and an intermediate address designation memory accessed by a lower address of a source MAC address of the packet, a bit 1 of an even parity bit of the fifth bit is stored at the sixth bit position, and a bit 1 is stored at the seventh bit position of a storage area of an address position of the SRAM accessed by an intermediate address of the source MAC address of the packet, and a bit 1 of an even parity bit of the seventh bit is stored at the eighth bit position, if the packet is a packet immediately after a destination base station change and is a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the bit 1s of the first bit, the second bit, the third bit, and the fourth bit or the bit 1s of the fifth bit, the sixth bit, the seventh bit, and the eighth bit are erased. On the other hand, if the packet is a packet immediately after a destination base station change and is not a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the source MAC address of the packet is stored in SRAM for an address table designating passage of the packet, and means for directing the packet to a ring node device in which a ring network interface NIC MAC address to which the server is connected via a router in a counterclockwise ring is stored as the destination MAC address of the packet is provided. When a packet from a server is sent out to a clockwise ring from a ring node device in which a NIC MAC address of the router is stored as the source MAC address of the packet via the router and the packet arrives at a device for adding, dropping, and passing the packet. When the destination MAC address of the packet is stored in the SRAM for the address table that designates the passage of the packet, the packet is sent forward to the right-handed ring. When the destination MAC address of the packet is not stored in the SRAM for the address table that designates the passage of the packet, and a bit 1 is stored at the 5th bit position of the storage area of the address position of the SRAM for the lower address and middle address designation memory accessed by the lower address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 7th bit is stored at the 6th bit position, and a bit 1 is stored at the 7th bit position of the storage area of the address position of the SRAM accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 7th bit is stored at the 8th bit position, the packet is sent out of the ring. When the destination MAC address of the packet is not stored in the SRAM for the address table that designates the passage of the packet, and a bit 1 is stored at the 1st bit position of the storage area of the address position of the SRAM for the lower address and middle address designation memory accessed by the lower address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 1st bit is stored at the 2nd bit position, and a bit 1 is stored at the 3rd bit position of the storage area of the address position of the SRAM accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 3rd bit is stored at the 4th bit position, the packet is sent out of the ring. Otherwise, the system is characterized by comprising means for sending the packet forward to the right-handed ring.

2. The mobile terminal further has a step of periodically accessing a received mail server and, when it cannot receive a response packet from the received mail server, sending a retransmission packet to the received mail server, the system according to claim 1.

3. When the mobile terminal sends a packet immediately after moving from the target base station to the device for adding, dropping, and passing packets of the target base station in the ring network, it sends a pre-mobility preparation packet with the source MAC address of the packet as the destination MAC address in a clockwise ring. When the packet arrives at the device for adding, dropping, and passing packets, if a bit 1 is stored at the 5th bit position of the storage area of the address position of the SRAM for the lower address and the middle address specified memory accessed by the lower address of the destination MAC address of the packet, a bit 1 of the even parity bit of the 7th bit is stored at the 6th bit position, and a bit 1 is stored at the 7th bit position of the storage area of the address position of the SRAM accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 7th bit is stored at the 8th bit position, the packet is sent out of the ring. If the destination MAC address of the packet is not stored in the SRAM for the address table specifying packet passing, and a bit 1 is stored at the 1st bit position of the storage area of the address position of the SRAM for the lower address and the middle address specified memory accessed by the lower address of the destination MAC address of the packet, a bit 1 of the even parity bit of the 1st bit is stored at the 2nd bit position, and a bit 1 is stored at the 3rd bit position of the storage area of the address position of the SRAM accessed by the middle address of the destination MAC address of the packet, and a bit 1 of the even parity bit of the 3rd bit is stored at the 4th bit position, the packet is sent out of the ring. Otherwise, the packet is sent forward in the clockwise ring. When the packet sent out of the ring arrives at the base station and the destination MAC address of the packet is not stored in the MAC address table and a MAC address with the same lower address as the lower address of the destination MAC address of the packet is stored, a repaired packet with the stored MAC address as the source MAC address is sent in a counterclockwise ring from the device for adding, dropping, and passing packets of the packets belonging to the home base station. When the repaired packet arrives at the device for adding, dropping, and passing packets,A bit 1 is stored at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the first bit is stored at the second bit position, and a bit 1 is stored at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the third bit is stored at the fourth bit position, or a bit 1 is stored at the fifth bit position of the storage area of the address position of the SRAM for the lower address and the middle address designation memory accessed by the lower address of the source MAC address of the packet, a bit 1 of the even parity bit of the fifth bit is stored at the sixth bit position, and a bit 1 is stored at the seventh bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and a bit 1 of the even parity bit of the seventh bit is stored at the eighth bit position. When this is the case, the system according to claim 1 is characterized in that it comprises means for storing the source MAC address of the repair packet in the SRAM for the address table designating the passage of the packet.

4. Insert devices for adding, dropping, and passing multiple packets into the ring network of the transmission path 2 of the clockwise ring and the transmission path 1 of the counterclockwise ring. Connect an L2 switch and a base station to the devices for adding, dropping, and passing the packets. Terminals and mobile terminals under the L2 switch and the base station respectively receive packets arriving from the counterclockwise ring of the ring network and transfer them to a router. When the source MAC address of a packet is the NIC MAC address of the router's ring network interface, the passing of the packet is blocked if the source MAC address of the packet is stored in the device's MAC address table. For the apex device on the ring network to communicate with a destination server via the connected router, packets from the terminals and mobile terminals are respectively sent between the router and themselves as Ethernet (registered trademark) frames of TCP, TCP, and UDP such as call signals across the ring network. Packets are sent back and forth between the router and the server, and between the router and the server or switch as IP packets. When a packet from the mobile terminal arrives at the device for adding, dropping, and passing packets in the ring network, regardless of whether the packet is a packet immediately after the mobile destination base station is changed and regardless of whether the packet is a communication start packet. Store bit 1 in the first bit position of the storage area of the SRAM for the lower address and the middle address specified memory accessed by the lower address of the source MAC address of the packet, store bit 1 of the even parity bit of the first bit in the second bit position, and store bit 1 in the third bit position of the storage area of the SRAM address position accessed by the middle address of the source MAC address of the packet, and store bit 1 of the even parity bit of the third bit in the fourth bit position. If only one of the first bit and the third bit is the first stored bit, store the source MAC address of the packet in the packet drop address table. On one hand, when storing a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address specification memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, when both the first bit and the third bit are the first stored bits, or when both bits are already stored, storing a bit 1 at the first bit position of the storage area of the address position of the SRAM for the lower address and the middle address specification memory accessed by the lower address of the source MAC address of the packet, storing a bit 1 of the even parity bit of the first bit at the second bit position, and storing a bit 1 at the third bit position of the storage area of the address position of the SRAM accessed by the middle address of the source MAC address of the packet, and storing a bit 1 of the even parity bit of the third bit at the fourth bit position, sending the packet to the left - handed ring, when the packet arrives at the device for packet add, drop, and pass, if the source MAC address of the packet is stored in the packet drop address table, erasing the MAC address, If a bit 1 is stored at a first bit position of a storage area of an address position of an SRAM for a lower address and an intermediate address specifying memory accessed by a lower address of a source MAC address of the packet, a bit 1 of an even parity bit of the first bit is stored at a second bit position, and a bit 1 is stored at a third bit position of a storage area of an address position of the SRAM accessed by an intermediate address of the source MAC address of the packet, and a bit 1 of an even parity bit of the third bit is stored at a fourth bit position, when the packet is a packet immediately after a destination base station change and is a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the bits 1 of the first bit, the second bit, the third bit, and the fourth bit are erased. On the other hand, when the packet is a packet immediately after a destination base station change and is not a packet of a base station movement in a direction in which the packet is transferred on a clockwise ring, the source MAC address of the packet is stored in an SRAM for an address table specifying passage of the packet, and the packet is directed to a ring node device in which a ring network interface NIC MAC address to which the server is connected via a router on a counterclockwise ring is stored as the destination MAC address of the packet. When a packet from a server is sent out from a ring node device in which a NIC MAC address of the router is stored as the source MAC address of the packet via the router to a clockwise ring and the packet arrives at a device for adding, dropping, and passing the packet. When the destination MAC address of the packet is stored in the SRAM for the address table that specifies the passage of the packet, the packet is sent forward to the right-ring. When the destination MAC address of the packet is stored in the packet drop address table, the packet is sent out of the ring. When the destination MAC address of the packet is not stored in the SRAM for the address table that specifies the passage of the packet, and the destination MAC address of the packet is not stored in the packet drop address table, and the first bit position of the storage area of the SRAM address position for the lower address and the middle address specifying memory accessed by the lower address of the destination MAC address of the packet stores a bit 1, the second bit position stores a bit 1 of the even parity bit of the first bit, and the third bit position of the storage area of the SRAM address position accessed by the middle address of the destination MAC address of the packet stores a bit 1, and the fourth bit position stores a bit 1 of the even parity bit of the third bit, the packet is sent out of the ring. Otherwise, the method includes the step of sending the packet forward to the right-ring. **Claim 5** The method according to claim 4, further comprising the step of the mobile terminal periodically accessing a receiving mail server and, when it cannot receive a response packet from the receiving mail server, sending a retransmission packet to the receiving mail server.

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