JP2023060780A - Handover that utilizes ring network using low-order address storing method - Google Patents

Abstract

To realize handover of a wireless system at a low cost and at a high speed.SOLUTION: In a method, in a case where a packet transmitted from a TCP portable terminal via a base station arrives at a device where a packet is added, dropped, or passed in a ring network or a tree-type ring network, when the packet is a packet arriving immediately after the base station is moved, a low-order address of a transmission source MAC address of the packet is stored in a low-order address memory designating packet sending by the device where a packet is added, dropped, or passed to the outside of the ring, and the transmission source MAC address is deleted from an address table, and then, the packet is directed to a server via a vertex device in a counterclockwise ring. In a case where the packet arrives at the device where a packet is added, dropped, or passed, the low-order address of the transmission source MAC address of the packet is deleted from the low-order address memory designating packet sending to the outside of the ring, and the packet is directed to the server via the vertex device in the counterclockwise ring.SELECTED DRAWING: Figure 2

Description

The present invention relates to handover using a ring network for transferring Ethernet packets using a MAC address lower order address storage method.

As a conventional example of the address storage method, there is Japanese Unexamined Patent Application Publication No. 2000-151617 entitled "Table Creation and Search Apparatus". This conventional example relates to a MAC address storage circuit, and includes a first table composed of a RAM having a matrix address, a MAC address data area, and an index area, a RAM having a matrix address, a MAC address data area, and an index area. and so on. In this conventional example, the entire 48-bit MAC address is stored in the location A, which designates the memory of the first table with the low-order bit string (for example, 16 bits). If another MAC address is already stored in the position A, it is recorded in the free address position B of the memory of the second table, and the recorded address position B is stored in the address position A of the first table. Store in the index area. This is a method of specifying recording areas by nesting.

Further, as a conventional technique of the address storage method, there is Japanese Unexamined Patent Application Publication No. 2004-15592 of Patent Document 2, "MAC Address Pointer Structure, MAC Address Rearrangement Method". This conventional example is a method of storing a plurality of MAC addresses in the same address position of the entry table specified by the low-order bit string. If there is no free area, the MAC address is stored in an entry table designated by a lower bit string different from the lower bit string of the MAC address.

As a conventional example of a ring network, a ring network using a master switch and a slave switch 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 allow frames to pass through, preventing congestion due to flooding. If a failure occurs in the ring network, the monitoring frame sent from the master switch and returned to the master switch will not be delivered. Instead, the failure notification frame will be delivered to the master switch from the slave switch at the failure point. unblock the blocked port of the to pass the frame. Also, a block port is set on the failed transmission line side of one of the slave switches at the failure point, and the operation of the ring network is maintained even after the failure of the ring network is recovered.

Further, as a conventional example of handover in a wireless network, there is Patent Document 4. In this prior art, the handover of a network that communicates with a mobile terminal via a base station from a control station that transfers ATM cells is performed by delay D1 from the control station to the mobile terminal via the source base station and When the difference in delay D2 from the control station to the mobile terminal is D2 (D1-D2>0), the ATM cell is delayed by the control station when the base station of the ATM cell sent from the control station to the mobile terminal is switched, This is a method that is executed by switching to prevent order reversal of ATM cells.

Moreover, there is Patent Document 5 as an example of another handover method. This prior art has a connection via a base station and a gateway between a mobile terminal and a server via a base station before switching and a connection via a switching destination base station, and packets via the connection reduce the disconnection time when the connection is switched. The method.

Japanese Patent Application Laid-Open No. 2000-151617 Japanese Patent Application Laid-Open No. 2004-15592 Retable 2008-068813 Japanese Patent Application Laid-Open No. 2001-128212 Retable 2017-195497

A conventional example of a conventional address storage method Japanese Patent Laid-Open No. 2000-151617 stores MAC addresses by nesting, so there is a problem that it takes a long time to trace the storage addresses. Also, since the entire 48 bits of the essential MAC address are stored, there is a problem that the storage area becomes large.

Further, Japanese Patent Application Laid-Open No. 2004-15592, which is a conventional example of a conventional address storage method, describes that if there is no space in the entry table position of the MAC address specified by the lower bit string, the MAC address is stored in the entry table position of a different lower bit string. However, in that case, when selecting a location to store the MAC address, it is necessary to search the entry table location specified by the two low-order bit strings, and at the same address location of the same entry table, Since there are multiple storage addresses, multiple address comparisons need to be made, and the problem is that retrieval is time consuming.
Searching for the MAC address by the low-order bit string is fast, but the method of basically storing the entire MAC address in the low-order bit string position is accurate storage. I have a few problems.
Patent Document 3, which is a conventional ring network, uses a MAC address table that uses 48-bit MAC addresses, so it has the drawback that the number of MAC addresses that can be stored is small.

In Patent Document 4 of the conventional handover, it is necessary to find the difference between the delay times of the route before switching and the route after switching from the control station to the mobile terminal. Since it can only be measured as half of the round-trip time from the terminal to the mobile terminal, there is a problem of lack of accuracy in measuring the delay time.

Further, in Patent Document 5 of conventional handover, since two connections are provided between the server and the mobile terminal for switching, it is necessary to identify the two connections, which has the drawback of complicating handover control.

SUMMARY OF THE INVENTION It is an object of the present invention to present a conventional address storage method that does not use a MAC address table, and to present a method for realizing easy handover and short-distance movement of mobile terminals using a ring network.

The present invention has been made in view of the above-mentioned problems of the prior art, and a first aspect of the present invention is to:
A packet in which a loopback bit is inserted and which a base station is accommodated in the lowest ring of a ring network or a tree-like ring network, and a mobile terminal under the base station arrives from a clockwise ring of the ring network or tree-like ring network. and MAC packet communication with a server or relay station via a gateway or router connected to a vertex device that blocks passage of Ethernet frames (registered trademark) (hereinafter referred to as MAC packets) other than OAM packets. A packet transfer system that enables movement between base stations of
When a MAC packet from the mobile terminal via the base station arrives at the packet add, drop, and pass device of the ring network or tree-like ring network,
When the base station gives a signal indicating that the packet is a packet immediately after moving the base station,
Storing the lower address of the source MAC address of the packet in a lower address memory designating packet transmission outside the ring of the device for adding, dropping and passing the packet, and transmitting the packet from the address table designating the passage of the packet. Remove the original MAC address and direct the packet to the server through the vertex device in the left-handed ring, sending the packet out of the ring if the packet reaches the packet add, drop and pass device delete the lower address of the source MAC address of the packet from the lower address memory that specifies the packet, and direct the packet to the server via the vertex device in a counterclockwise ring;
On the other hand, if the packet is not a packet immediately after moving the base station,
The lower address of the source MAC address of the packet is stored in the lower address memory that designates the packet transmission outside the ring of the device for adding, dropping and passing the packet, and the packet is sent to the server via the vertex device in the counterclockwise ring. When the packet arrives at the packet add, drop and pass device, and when the lower address of the source MAC address of the packet is stored in the lower address memory designating the packet transmission out of the ring means for storing the source MAC address of the packet in an address table specifying passage of the packet, and directing the packet to the server via a vertex device in a counterclockwise ring;
When a response incoming packet of a voice call packet from said server or an SMS (Short Message Service) packet or the first incoming packet of FTP arrives at the packet add, drop and pass device in a clockwise ring,
If the destination MAC address of the packet is stored in the address table that specifies the passage of the packet, send the packet toward the packet add, drop, and pass devices ahead of the clockwise ring, and is not stored in the address table that specifies the passage of the packet, and the lower address of the destination MAC address of the packet is stored in the lower address memory that specifies sending the packet out of the ring copy the packet, send the copy packet out of the ring, send the original packet clockwise around the ring to the add, drop, and pass devices of the packet ahead of the ring, and if so, forwarding the packet to a forward packet add, drop and pass device on the clockwise ring;
On the other hand, when a packet other than a response incoming packet of a voice call packet from the server, an SMS (Short Message Service) packet, or the first incoming packet of FTP arrives at the packet add, drop, and pass device in the clockwise ring. ,
If the destination MAC address of the packet is stored in the address table specifying the passage of the packet, send the packet toward the packet add, drop and pass devices ahead of the clockwise ring. , when the destination MAC address of the packet is not stored in an address table that specifies packet passage, and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring; means for sending said packet out of the ring if it is, and for sending said packet clockwise to forward packet add, drop and pass devices in the ring otherwise. prepared,
Means for sending a location registration packet having a source MAC address from a mobile terminal or a base station in use of said mobile terminal, when a passing base station changes or periodically, or a mobile terminal or a base station in use of said mobile terminal means for causing the sending of a unidirectional routing packet having a source MAC address from
means for causing the mobile terminal to send a retransmission packet, a retransmission request packet, or a communication partner confirmation packet to the server when no packet arrives from the server to the mobile terminal for a predetermined time or longer during communication. is a packet forwarding system.

A second aspect of the present invention is the packet transfer system according to the first aspect of the present invention,
the device for adding, dropping, and passing packets separately has a lower address memory for designating passing of packets;
when a packet arrives at a device for adding, dropping, and passing packets from the counterclockwise ring, storing a lower address of the source MAC address of the packet in a lower address memory designating passage of the packet;
When a packet arrives at a packet add, drop, and pass device from outside the ring, and if the packet is a packet that has just moved from the base station, the lower address of the source MAC address of the packet is added to the packet. from the lower address memory that specifies the passage of the
When a packet arrives at a packet add, drop, and pass device from the clockwise ring, the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies the pass of the packet, and the The packet transfer system further comprises means for discarding the packet when the lower address of the destination MAC address is not stored in the lower address memory designating packet transmission outside the ring.

A third aspect of the present invention is packet waiting means applied to either the packet transfer system of the first aspect of the present invention or the packet transfer system of the second aspect of the present invention,
The source MAC address of a packet from a mobile terminal to a server or a relay station via a base station, a ring network or a tree-like ring network is set as the own packet of the router or gateway connected to the top device of the ring network or the tree-like ring network. store the packet in the first memory of the standby means and send the packet to the server, or put the source MAC address of the packet to the server in the option area of the IP header of the IP packet and send it to the server; ,
A packet having a signal indicating that a lower address is not yet stored in a lower address memory designating packet transmission outside the ring of a device for adding, dropping, and passing packets of the ring network is sent to the own packet waiting means. If received by
If a MAC address different from the MAC address having the lower address of the source MAC address of the received packet as a lower address is stored in the first memory of the packet waiting means, the MAC address is stored in the first memory. storing the MAC address in the second memory of its own packet waiting means;
Alternatively, if the first memory of the self-packet waiting means is not used, the source MAC address of the received packet is stored in the second memory of the self-packet waiting means,
In the method that does not use the first memory of the self-packet waiting means, the same lower address as the MAC address stored in the second memory of the self-packet waiting means is assigned to the IP packet of the packet arriving from the server. If the lower address of the MAC address written in the option area of the IP header of is different from the MAC address written in the memory 2, the MAC address is stored in the memory 2, and until the source MAC address of the packet arriving from the terminal side is stored in the second memory of the self-packet waiting means, the packet is sent to the terminal side, and then the self-waiting means waits for the packet. Erasing the MAC address of the same lower address as the MAC address and its lower address stored in the second memory of the means, or
In the method using the first memory of the packet waiting means, when the destination IP address of the IP packet arriving from the server to the own packet waiting means is stored in the second memory of the own packet waiting means , causing the packet to wait until a retransmission request packet or a retransmission packet arrives from the mobile terminal whose source MAC address is the MAC address corresponding to the destination IP address stored in the second memory; when a packet or a retransmission packet arrives, erasing the source MAC address and the source IP address of the retransmission request packet or the retransmission packet from the second memory of the self-packet waiting means;
This packet waiting means is characterized by:

A fourth aspect of the present invention designates packet add, drop, and passing devices of the ring network or tree-like ring network of the packet transfer system according to the first aspect of the present invention, and sends packets out of the ring. Each bit of parallel data read from a lower address memory, which is a lower address memory that designates packet transmission to the outside of the ring, is addressed by the upper part of the lower address of the source MAC address and the lower order of the source MAC address A latch signal of parallel data logically ORed with each bit of parallel data obtained by decoding the lower part of the address is specified in the lower address memory for designating packet transmission out of the ring or in the lower address memory for designating passage of the packet. a memory that inserts and stores the lower part of the lower address of the source MAC address as bit 1 at the position of bit 1 of decoding as bit 1 that means lower address storage,
When deleting the lower address of the source MAC address from the lower address memory that specifies packet transmission outside the ring, the lower address memory that specifies packet transmission outside the ring is replaced with the upper part of the lower address of the source MAC address. Each bit of the parallel data read from the addressed position and the bit-inverted bit of each bit of the parallel data decoded from the lower part of the lower address of the transmission source MAC address are logically ANDed to the outside of the ring. By storing the lower address portion of the lower address of the transmission source MAC address in the address specifying position of the lower address memory designating packet transmission, bit 0 is inserted into the position of decode bit 1 as bit 0 meaning no lower address storage. It is a lower address memory for designating packet add, drop and passing devices for packet transmission outside the ring of a ring network or tree-like ring network of a packet transfer system.

In a fifth aspect of the present invention, a base station is accommodated in the lowest ring of a ring network or tree-like ring network, and mobile terminals under the base station arrive from the clockwise ring of the ring network or tree-like ring network. Between base stations of mobile terminals in a network that performs MAC packet communication with a server or relay station via a gateway or router connected to a vertex device that blocks passage of MAC packets other than packets with loopback bits inserted and OAM packets A packet transfer method that enables movement,
When a MAC packet from the mobile terminal via the base station arrives at the packet add, drop, and pass device of the ring network or tree-like ring network,
When the base station gives a signal indicating that the packet is a packet immediately after moving the base station,
Storing the lower address of the source MAC address of the packet in a lower address memory designating packet transmission outside the ring of the device for adding, dropping and passing the packet, and transmitting the packet from the address table designating the passage of the packet. Remove the original MAC address and direct the packet to the server through the vertex device in the left-handed ring, sending the packet out of the ring if the packet reaches the packet add, drop and pass device delete the lower address of the source MAC address of the packet from the lower address memory that specifies the packet, and direct the packet to the server via the vertex device in a counterclockwise ring;
On the other hand, if the packet is not a packet immediately after moving the base station,
The lower address of the source MAC address of the packet is stored in the lower address memory that designates the packet transmission outside the ring of the device for adding, dropping and passing the packet, and the packet is sent to the server via the vertex device in the counterclockwise ring. When the packet arrives at the packet add, drop and pass device, and when the lower address of the source MAC address of the packet is stored in the lower address memory designating the packet transmission out of the ring storing the source MAC address of the packet in an address table specifying passage of the packet, and directing the packet to the server via a vertex device in a counter-clockwise ring;
When a response incoming packet of a voice call packet from said server or an SMS (Short Message Service) packet or the first incoming packet of FTP arrives at the packet add, drop and pass device in a clockwise ring,
If the destination MAC address of the packet is stored in the address table that specifies the passage of the packet, send the packet toward the packet add, drop, and pass devices ahead of the clockwise ring, and is not stored in the address table that specifies the passage of the packet, and the lower address of the destination MAC address of the packet is stored in the lower address memory that specifies sending the packet out of the ring copy the packet, send the copy packet out of the ring, send the original packet clockwise around the ring to the add, drop, and pass devices of the packet ahead of the ring, and if so, forwarding the packet to a forward packet add, drop and pass device on the clockwise ring;
On the other hand, when a packet other than a response incoming packet of a voice call packet from the server, an SMS (Short Message Service) packet, or the first incoming packet of FTP arrives at the packet add, drop, and pass device in the clockwise ring. ,
If the destination MAC address of the packet is stored in the address table specifying the passage of the packet, send the packet toward the packet add, drop and pass devices ahead of the clockwise ring. , when the destination MAC address of the packet is not stored in an address table that specifies packet passage, and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring; if so, forwarding said packet out of the ring; otherwise, forwarding said packet clockwise around the ring towards forward packet add, drop and pass devices. have
A step of transmitting a location registration packet having a source MAC address from a mobile terminal or a base station in use of said mobile terminal when a passing base station changes or periodically, or a mobile terminal or a base station in use of said mobile terminal. causing the sending of unidirectional routing packets with source MAC addresses from
and a step of causing the mobile terminal to send a retransmission packet, a retransmission request packet, or a communication partner confirmation packet to the server when no packet has arrived from the server to the mobile terminal for a predetermined time or longer during communication. It is a packet forwarding method that

A sixth aspect of the present invention is the packet transfer method according to the fifth aspect of the present invention, wherein the device for adding, dropping, and passing packets further comprises a lower address memory for designating passage of packets,
when a packet arrives at a device for adding, dropping, and passing packets from the counterclockwise ring, storing a lower address of the source MAC address of the packet in a lower address memory designating passage of the packet;
When a packet arrives at a packet add, drop, and pass device from outside the ring, and if the packet is a packet that has just moved from the base station, the lower address of the source MAC address of the packet is added to the packet. from the lower address memory that specifies the passage of the
When a packet arrives at a packet add, drop, and pass device from the clockwise ring, the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies the pass of the packet, and the The packet transfer method further comprises the step of discarding the packet when the lower address of the destination MAC address is not stored in the lower address memory designating packet transmission outside the ring.

As described above, the present invention reduces the storage bit length to only the lower address of the MAC address, increases the number of addresses to be stored in the memory, and eliminates the lower address omission of the conventional MAC address table. The address storage method is applied to a 1-bit storage method that means low-order address storage in a low-order address memory that designates packet transmission out of the ring of a ring network packet add, drop, and passing device that transfers Ethernet frames. Since this is a method of realizing handover of mobile terminals using a ring network, power consumption and system cost can be suppressed, and high-speed communication is possible.

In the first embodiment of the present invention, a plurality of Ethernet packets having an address table for designating packet passage, a lower address memory for designating packet transmission outside the ring, and a lower address memory for designating packet passage. A diagram for explaining the handover operation of a network that uses a ring network in which packet add, drop, and pass devices are connected by optical transmission lines for communication between a mobile terminal and a server. A device for adding, dropping and passing a plurality of packets having an address table for designating passage of packets and a lower address memory for designating transmission of packets out of the ring for transferring Ethernet packets according to the second embodiment of the present invention. A diagram for explaining handover operation of a network that uses a ring network connected by an optical transmission line for communication between a mobile terminal and a server. A device for adding, dropping, and passing a plurality of packets having an address table for designating passage of packets and a lower address memory for designating transmission of packets out of the ring for transferring Ethernet packets according to the third embodiment of the present invention. A diagram for explaining handover operation of a network that uses a ring network connected by an optical transmission line for communication between a mobile terminal and a server. A device for adding, dropping, and passing a plurality of packets having an address table for designating passage of packets and a lower address memory for designating transmission of packets out of the ring for transferring Ethernet packets according to the fourth embodiment of the present invention. A diagram for explaining handover operation of a network that uses a ring network connected by an optical transmission line for communication between a mobile terminal and a server.

A first embodiment of the present invention will be described with reference to FIG. This embodiment includes a plurality of packet add, drop, and pass devices having an address table for designating packet passage, a lower address memory for designating packet transmission outside the ring, and a lower address memory for designating packet passage. This is an example of handover operation using a ring network in which a server transfers Ethernet packets composed of vertex devices connected via routers. Said server is an Internet connection server.

In FIG. 1, 1-1 is a subscriber system counterclockwise optical ring, 1-2 is a subscriber system clockwise optical ring, 2 and 3 are subscriber system rings, 4 is an upper ring, 5 is a vertex device, and 6 -1, 6-2, 6-3 are packet add, drop and pass devices, 7 is a lower address memory that designates packet transmission outside the ring, 8 is an address table that designates packet passage, and 10 is a packet. 22 is a router; 12-1, 12-2, 12-3, 12-4 and 12-5 are base stations; 13-1, 13-2 and 13-3 are TCP mobile A terminal, 14 is a mobile terminal, and 20 is a server. Also, (1) to (33) are packets, and I0, I1, I2, I3, and I4 are domestic or regional IP addresses of service providers. or an IPv6 address.
Note that the address table 8 for designating passage of packets is an address table with a small number of stored MAC addresses that does not store port numbers, unlike conventional MAC address tables.

The operation of FIG. 1 will be described below. First, it is assumed that the IP address I1 of the router 22 and the MAC address r1r2 of the ring transmission interface are already stored in the ARP tables of the TCP mobile terminals 13-1, 13-2, and 13-3. The TCP mobile terminal 13-1 sends packet (1) Mr1r2a1a2 (I0) (M indicates an Ethernet packet, r1 indicates the upper MAC address of the interface of the router 22, r2 indicates the lower MAC address of the interface of the router 22, a1a2 indicates the upper MAC address a1 and the lower MAC address a2, which are the MAC addresses of the TCP mobile terminal 13-1, and I0 indicates the IP address of the destination server 20) to the packet add, drop, and pass device 6-1. Here is an example sent. When the packet reaches the add, drop, and pass device 6-1 from the TCP mobile terminal 13-1, the lower address a2 of the source MAC address of the packet is set to the lower address that designates the transmission of the packet out of the ring. It is stored in the address memory 7. The packet is forwarded by (2) Mr1r2a1a2 (I0) on counterclockwise optical ring 1, and arrives at packet add, drop and pass device 6-2.

When the packet (2) Mr1r2a1a2 (I0) arrives at the packet add, drop and pass device 6-2, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 10 for designating passage of the packet. The packet is forwarded by (3) Mr1r2a1a2 (I0) on counterclockwise optical ring 1, and arrives at packet add, drop and pass device 6-3.

When the packet (3) Mr1r2a1a2 (I0) arrives at the packet add/drop/pass device 6-3, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 10 for designating passage of the packet. The packet is forwarded by (4) Mr1r2a1a2 (I0) on counterclockwise optical ring 1 and arrives at vertex device 5 as shown in the figure. The packet is sent outside the ring and reaches the router 22 via the upper ring 4 . The upper ring 4 has the same configuration as the subscriber system rings 1, 2 and 3 and operates in the same manner.

When the packet (5) Mr1r2a1a2 (I0) arrives at the router 22, the source MAC address a1a2 and the source IP address I2 of the packet are stored in the memory 1 (not shown). The output port corresponding to the destination of the destination IP address I0 of the packet is found and sent to that port. The packet is shown by (6) IPI2I0 (IP indicates an IP address, I2 indicates the IP address of the source terminal 13-1, and I0 indicates the IP address of the destination server 20). , and reaches the server 20 .

Next, the TCP portable terminal 13-2 sends packet (7) Mr1r2a3a2 (I0) (M indicates an Ethernet packet, r1 indicates the upper MAC address of the interface of the router 22, and r2 indicates the lower MAC address of the interface of the router 22). , a3a2 indicate the upper MAC address a3 and the lower MAC address a2, which are the MAC addresses of the terminal 13-2, and I0 indicates the IP address of the server 20, which is the destination. send to When the packet reaches the add, drop, and pass device 6-1 from the TCP mobile terminal 13-2, the lower address a2 of the source MAC address of the packet is set to the lower address that designates the transmission of the packet out of the ring. It is stored in the address memory 7. The packet is forwarded by (8) Mr1r2a3a2 (I0) on counterclockwise optical ring 1, and arrives at packet add, drop and pass device 6-2.

When the packet (8) Mr1r2a3a2 (I0) arrives at the packet add/drop/pass device 6-2, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 10 for designating passage of the packet. The packet is forwarded by (9) Mr1r2a3a2 (I0) on counterclockwise optical ring 1, and reaches vertex device 5 via packet add, drop and pass device 6-3.

The packet arriving at the vertex device 5 is sent outside the ring and reaches the router 22 via the upper ring 4 .

When the packet (11) Mr1r2a3a2 (I0) arrives at the router 22, after storing the source MAC address a3a2 and the source IP address I3 of the packet in the memory 1 (not shown), the destination IP address I0 of the packet is stored. Reads the output port corresponding to , and sends it to that port. The packet is shown by (12) IPI3I0 (IP indicates an IP address, I3 indicates the IP address of the source terminal 13-2, and I0 indicates the IP address of the destination server 20). , and reaches the server 20 .

Next, when the TCP mobile terminal 13-2 moves under the control of the base station 12-2 and the packet (13) Mr1r2a3a2 (I0) arrives at the base station 12-2, a signal g indicating that the base station has moved is input. , packet add, drop and pass device 6-2. When the packet from the TCP portable terminal 13-2 reaches the add, drop and pass device 6-2, a lower address memory for designating transmission of the packet out of the ring with the lower address a2 of the source MAC address of the packet. Store in 7. Since the lower address is stored in a memory state in which the lower address is not yet stored in the lower address memory 7, a signal G to that effect is inserted into the packet, and the lower address of the source MAC address of the packet is stored. Since a2 is stored in the lower address memory 10 that designates the passage of the packet, and that packet is a packet that has just moved from one base station to another, the lower address a2 is erased as indicated by the horizontal line in FIG. The packet is forwarded on counterclockwise optical ring 1 by (14) Mr1r2a3a2gG (I0) as shown in the figure and directed to packet add, drop and pass device 6-3.

When the packet (14) Mr1r2a3a2gG (I0) arrives at the packet add/drop/pass device 6-3, the packet is a packet that has just moved from the base station, so the lower address a2 of the source MAC address of the packet is is stored in the lower address memory 7 designating packet transmission outside the ring, the stored lower address a2 is erased, and the lower address a2 of the source MAC address of the packet is replaced with the lower address designating the passage of the packet. Store in memory 10 . The packet is forwarded by (15) Mr1r2a3a2gG (I0) on counterclockwise optical ring 1 and reaches vertex device 5 as shown in the figure.

The packet arriving at the vertex device 5 is sent outside the ring and reaches the router 22 via the upper ring 4 .

When the packet (16) Mr1r2a3a2gG (I0) arrives at the router 22, after storing the source MAC address and the source IP address of the packet in the memory 1 (not shown), it corresponds to the destination IP address I0 of the packet. The specified lower address is still in the lower address memory 7 which reads out the output port to be used, sends it to that port, and specifies packet add, drop, and packet sending to the outside of the ring of the pass device for the packet (16) Mr1r2a3a2gG. The IP address I2 corresponding to the MAC address a1a2 of the same lower address as the lower address a2 of the transmission source MAC address of the packet is given because the indication G indicating that the lower address is stored in the memory state that is not stored. are read from the storage address of the memory 1 (not shown in the figure) and stored in the memory 2 (not shown in the figure). When the destination IP address I2 of the IP packet arriving from the server is stored in the memory 2, the packet from the server 20 with the IP address I2 is sent from the TCP portable terminal side to the MAC address corresponding to the I2 source MAC address. until it receives the retransmission packet (24) Mr1r2a1a2 (I0) of the MAC address a1a2 read from the memory 2 not shown in the figure, in a buffer not shown in the figure. This is done to prevent the packet of the destination MAC address of the lower address a2 from being erroneously sent out of the ring during clockwise optical ring transfer. If the lower address of the source MAC address of the retransmitted packet is stored in the lower address memory 7 that designates the packet to be sent out of the ring, the erroneous transmission out of the ring means that the source MAC address of the retransmission packet is stored. By storing a1a2 in the address table 8 that specifies the passage of the packet, the packet passes through the device for add, drop and passage, thereby eliminating erroneous drop. When the packet (24) Mr1r2a1a2 (I0) is received, the packet from the server with the IP address I2 and the waiting packet from the server with the IP address I3 are sent to (25) Ma3a2r1r2 (I3) and (26) Ma1a2r1r2. It is sent to the vertex device 5 via the upper ring 4 as illustrated by (I2).
Here, the packet of Ma3a2r1r2(I3) is delayed in a buffer (not shown) until the retransmission packet of source MAC address a3a2 is received.

Returning to the above description, the packet (17) IPI3I0 (IP indicates an IP address, I3 indicates the IP address of the source terminal 13-2, and I0 indicates the IP address of the destination server 20) is shown in FIG. , and reaches the server 20 .

Regarding the packet (24) Mr1r2a1a2(I0), the retransmission packet from the terminal 13-1 passes through the packet add, drop and pass device 6-1 as illustrated by the packet (20) Mr1r2a1a2(I0). via (21) Mr 1 r 2 a 1 a 2 (I 0 ) is forwarded to the packet add, drop and pass device 6-2 on the counterclockwise optical ring 1-1. When the packet arrives at the packet add, drop, and pass device 6-2, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 for designating packet transmission out of the ring. Therefore, the source MAC address a1a2 of the packet is stored in the address table 8 for designating passage of the packet. The packet is forwarded by (22) Mr1r2a1a2 (I0) through counterclockwise optical ring 1-1 as shown in FIG.

Next, the procedure for transferring the packets (25) Ma3a2r1r2(I3) and (26) Ma1a2r1r2(I2) arriving at the vertex device 5 through the clockwise optical ring 2 will be described. Packets (27) Ma3a2r1r2(I3) and (28) Ma1a2r1r2(I2) are transferred as shown in the figure and arrive at packet add, drop and pass device 6-3. The two packets are not stored in the lower address memory 7 where the lower address of the destination MAC address designates packet transmission outside the ring, and the lower address memory 7 where the lower address a2 of the destination MAC address designates packet passage. 10, it passes through the packet add, drop and pass device 6-3.

The two packets are transferred by (29) Ma3a2r1r2 (I3) and (30) Ma1a2r1r2 (I2) as shown in the figure and arrive at the packet add, drop and pass device 6-2. For packet (29) Ma3a2r1r2 (I3), the destination MAC address a3a2 is not stored in the address table 8 specifying packet passage, and the lower address a2 of the destination MAC address specifies packet transmission outside the ring. Since it is stored in the lower address memory 7, it is sent out of the ring and reaches the terminal 13-2 by (31) Ma3a2r1r2 (I3) as shown in the figure. On the other hand, the packet (30) Ma1a2r1r2 (I2) is stored in the address table 8 where the destination MAC address a1a2 specifies the passage of the packet. , is sent out of the ring by the packet add, drop and pass device 6-1, and reaches the terminal 13-1.

In the above embodiment 1, the router 22 waits for a packet when it detects a signal that is a packet immediately after changing the base station. should do the same. In that case, the detection of the communication start packet does not become a judgment of Layer 3, but there is no big problem because only the communication start bit fin bit and the ACK bit of the TCP header are seen and the TCP header is not written.

Further, the TCP portable terminal 13-2 shown in the first embodiment moves under the control of the base station 12-2, and the sent packet (13) Mr1r2a3a2 (I0) is added, dropped, and passed through the device 6-2. When the packet arrives at the device for adding, dropping, and passing packets, the source MAC address of the packet designates the passage of the packet. If the address is stored in the address table, erase that address, and replace the lower address of the source MAC address of the packet from the lower address memory that specifies packet transmission out of the ring and from the lower address memory that specifies the passage of the packet. An action to delete may be added.

In the first embodiment described above, the TCP mobile terminal 13-2 is an example of transit base station movement in the direction toward the server in the ring network. , when a packet from the counterclockwise ring 1 arrives at the packet add, drop and pass device 6-2 due to the packet immediately after the base station moves, the packet reaches the ring of the packet add, drop and pass device 6-2. If the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 that designates packet transmission to the outside, the lower address a2 is erased. At that time, the passing device does not store a lower address that is not stored in the lower address memory 7 designating the packet to be sent out of the ring, so the signal G is not inserted into the packet. When a packet to which a signal g indicating a packet immediately after movement from the TCP mobile terminal 13-2 is added arrives at the router 22, the signal G is not included in the packet and the packet waiting means does not work.
However, a packet from a TCP portable terminal not shown in the drawing under the control of the base station 12-2 arrives at the packet add, drop and pass device 6-2, and is sent to the lower address memory 7 that designates packet transmission out of the ring. When an event occurs in which the lower address a2 of the source MAC address of the packet is stored for the first time, it is necessary to insert the signal G into the packet and send it to the router 22 to operate the packet waiting means.

In the first embodiment, a packet from the server from the clockwise ring 2 arrives at the packet add, drop, and pass device, and the destination MAC address of the packet is stored in the address table that specifies the pass of the packet. the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies the passage of the packet, and the lower address of the destination MAC address of the packet specifies the transmission of the packet out of the ring. If not stored in memory, the packet can be discarded.

In addition, in the first embodiment described above, an example was shown in which the lower address of the source MAC address is stored in the lower address memory that specifies the passage of the packet and the lower address memory that specifies the transmission of the packet out of the ring.
Storing the lower address of the source MAC address of the packet in the lower address memory designating the passage of the packet or in the lower address memory designating the transmission of the packet out of the ring means It is also possible to store bit 1, which means lower address storage, at a position addressed by a lower address of the source MAC address in a lower address memory that specifies packet transmission to.
Alternatively, storing the lower address of the transmission source MAC address of the packet in a lower address memory that specifies packet passage or in a lower address memory that specifies packet transmission out of the ring is a lower address memory that specifies packet passage. Alternatively, decode each bit of the parallel data read from the lower address memory designating packet transmission outside the ring from the location addressed by the upper part of the lower address of the source MAC address and the lower part of the lower address of the source MAC address. by storing a latch signal of the parallel data obtained by ORing the parallel data with each bit of the parallel data in the address specifying position of the lower address memory specifying the passage of the packet or the lower address memory specifying the transmission of the packet out of the ring; It is also possible to insert and store the bit 1 at the position of the decode bit 1 of the lower part of the lower address of the source MAC address as the bit 1 indicating lower address storage.

A second embodiment of the present invention will be described with reference to FIG. This embodiment is a tree-like ring network in which a plurality of packet add, drop, and pass devices having an address table that specifies packet passage and a lower address memory that specifies packet transmission outside the ring are connected by optical transmission lines. is an example of handover operation using a ring network that transfers Ethernet packets used for communication between a mobile terminal under the control of a base station and a server. In this embodiment, the router 22 is provided with packet waiting means, and the SMS packets and voice MAC packets arriving from the terminal and directed to the relay station 26 and the UDP and TCP packets directed to the server 20 are used as the destination IP address of the relay station. Sort by destination IP address to the server, or distribute packet destinations by destination MAC address corresponding to them. The source MAC address of the MAC packet arriving at the router 22 from the terminal side is inserted into the option area of the IP header of the IP packet directed to the relay station 26 . Hereinafter, in this embodiment, an example in which a TCP mobile terminal and the server 20 communicate will be shown.

In FIG. 2, 19-1, 19-2 and 19-3 are mobile terminals, 26 is a relay station, 27 is a home memory, and the other symbols that are the same as in FIG. 1 mean the same things.

The operation of FIG. 2 will be described below. First, it is assumed that the IP address I1 of the router 22 and the MAC address r4r5 of the ring transmission line interface of the router 22 are already stored in the ARP tables of the mobile terminals 19-1, 19-2, and 19-3. A gateway may be placed instead of the router 22 . When the mobile terminal 19-1 receives a packet (1) Mr4r5a1a2 (I0) (M indicates an Ethernet packet, r4 indicates the upper MAC address of the interface of the router 22, r5 indicates the lower MAC address of the interface, and a1a2 is the mobile terminal 19-1. and I0 indicates the IP address of the destination server 20) is sent to the packet add, drop and pass device 6-1. When the packet reaches the packet add/drop/pass device 6-1 from the portable terminal 19-1, the lower address memory designates the packet transmission out of the ring with the lower address a2 of the source MAC address of the packet. Store in 7. The packet is forwarded by (2) Mr4r5a1a2 (I0) on counterclockwise optical ring 1-1, and arrives at packet add, drop and pass device 6-2.

When the packet (2) Mr4r5a1a2 (I0) arrives at the packet add, drop and pass device 6-2, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (3) Mr4r5a1a2 (I0) in the counterclockwise optical ring 1 as shown in the figure, and arrives at the packet add, drop and pass device 6-3. do.

When the packet (3) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-3, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (4) Mr4r5a1a2 (I0) in the counterclockwise optical ring 1 and arrives at the vertex device 5 as it is. The packet is sent outside the ring and reaches the router 22 via the upper ring 4 . The upper ring 4 has the same configuration as the subscriber system ring 1 and the subscriber system rings 2 and 3 of the counterclockwise ring 1-1 and the clockwise ring 1-2, and operates in the same manner.

When the packet (5) Mr4r5a1a2 (I0) arrives at the router 22, the router 22 stores the source MAC address a1a2 and the source IP address I2 of the packet in the memory 1 (not shown), and Search the IP table and send the packet from the output port to the server as an IP packet. The IP packet is IPI2I0 (IP indicates the IP address, I2 indicates the IP address of the mobile terminal 19-1, and I0 indicates the IP address of the server 20).
Similarly, for packet (6) Mr4r5a3a2 (I0) from mobile terminal 19-2, the packet is sent to lower address memory 7 that designates the packet to be sent outside the ring of device 6-1 for adding, dropping, and passing packets. The lower address a2 of the original MAC address is stored, and the packet is transferred through the ring network and reaches the server 20 via the router 22. FIG. Similarly, for packet (13) Mr4r5a4a2 (I0) from mobile terminal 19-3, the packet is sent to lower address memory 7 that designates the packet to be sent outside the ring of device 6-3 for adding, dropping, and passing packets. The lower address a2 of the original MAC address is stored, and the packet is transferred through the ring network and reaches the server 20 via the router 22. FIG.

Next, an example is shown in which the mobile terminal 19-1 sends a packet (15) Mr4r5a1a2 (I0) addressed to the server 20 to the packet add, drop and pass device 6-1. When the packet reaches the packet add/drop/pass device 6-1 from the portable terminal 19-1, the lower address memory designates the packet transmission out of the ring with the lower address a2 of the source MAC address of the packet. Store in 7. The packet is forwarded by (16) Mr4r5a1a2 (I0) on the counterclockwise optical ring 1-1, and arrives at the packet add, drop and pass device 6-2.

When the packet (16) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-2, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (17) Mr4r5a1a2 (I0) in the counterclockwise optical ring 1 as shown in the figure, and arrives at the packet add, drop and pass device 6-3. do.

When the packet (17) Mr4r5a1a2 (I0) arrives at the packet add, drop and pass device 6-3, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is stored in the memory 7, the source MAC address a1a2 of the packet is stored in the address table 8 for designating passage of the packet. The packet is forwarded by (18) Mr4r5a1a2 (I0) on counterclockwise optical ring 1 and arrives at vertex device 5 as shown. The packet is sent outside the ring and reaches the router 22 via the upper ring 4 .

When the packet (18) Mr4r5a1a2 (I0) arrives at the router 22, the router 22 stores the source MAC address a1a2 and the source IP address I2 of the packet in the memory 1 (not shown), and sends the IP address to the server 20. It is sent as a packet IPI2I0 (IP indicates an IP packet, I2 indicates the home source IP address of the source mobile terminal, and I0 indicates the IP address of the destination server 20).

When the response packet IPI0I2 of the packet from the server 20 arrives at the router 22, the MAC address a1a2 corresponding to the destination IP address I2 is read from the memory 1 not shown in the figure, and the packet with the destination MAC address is generated. (20) By Ma1a2r4r5c (I2) (M indicates an Ethernet frame, a1 of a1a2 indicates the upper MAC address of the destination mobile terminal 19-1, a2 indicates the lower MAC address, and r4r5 indicates the MAC address of the ring interface of the router 22) It is sent to the clockwise ring 1-2 of the subscriber ring 1 via the upper ring 4 as shown in the figure.

When the packet (21) Ma1a2r4r5c (I2) transferred through the clockwise ring 1-2 arrives at the packet add, drop and pass device 6-3, the destination MAC address a1a2 of the packet designates the pass of the packet. Since it is stored in the address table 8, it passes through that device and arrives at the packet add, drop and pass device 6-2 as (22) Ma1a2r4r5c (I2). When (22) Ma1a2r4r5c (I2) arrives at the device 6-2 for adding, dropping, and passing packets, the lower address of the destination MAC address of the packet is stored in the lower address memory for designating packet transmission outside the ring. Since it is not stored at the time, it is passed through that device and forwarded down the clockwise ring 1-2 as shown in the diagram at (23) Ma1a2r4r5c (I2). The packet is sent out of the ring by the packet add, drop, and pass device 6-1 in which the lower address of the destination MAC address of the packet is stored in the lower address memory designating the packet transmission outside the ring ( 24) It is sent as Ma1a2r4r5c (I2) and reaches the portable terminal 19-1.

Next, when the mobile terminal 19-2 moves under the control of the base station 12-2 and the packet (25) Mr4r5a3a2 (I0) arrives at the base station 12-2, the base station moves to the option area of the IP header of the packet. A signal g to that effect is entered and sent to the packet add, drop and pass device 6-2. When the packet from the portable terminal 19-2 reaches the add, drop and pass device 6-2, the lower address memory 7 designates the lower address a2 of the source MAC address of the packet to send the packet out of the ring. memorize to Since the lower address a2 is stored in a state in which the lower address a2 is not stored in the lower address memory 7 for designating packet transmission to the outside of the ring, a signal h to that effect is added to the packet as a base station movement signal. It is inserted for distinction, but is not shown in the transfer packet in the figure.
The packet is sent by (26) Mr4r5a3a2g (I0) in counterclockwise optical ring 1-1 to the effect that the packet is a packet immediately after the base station has moved. It reaches the device 6-3.

When the packet (26) Mr4r5a3a2g (I0) arrives at the packet add/drop/pass device 6-3, the packet is a packet that has just moved from the base station, so the lower address a2 of the source MAC address of the packet is is stored in the lower address memory 7 designating packet transmission outside the ring, the stored lower address a2 is erased. In the figure, since the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 that designates packet transmission to the outside of the ring, a horizontal line is drawn to indicate that it has been erased. there is The packet is forwarded by (27) Mr4r5a3a2g (I0) on counterclockwise optical ring 1 and reaches vertex device 5 as shown.

The packet arriving at the vertex device 5 is sent outside the ring and reaches the router 22 via the upper ring 4 .

When the packet (27) Mr4r5a3a2gp (I0) arrives at the router 22, the packet ( 27) In Mr4r5a3a2gp, if the lower address of the source MAC address of the packet is stored in the lower address memory that designates the addition, drop, and transmission of the packet to the outside of the ring of the device that passes through the ring network with that packet, then that Since the signal p indicating that the lower address is stored when the lower address is not yet stored in the memory is given, the MAC address of the same lower address as the lower address a2 of the source MAC address of the packet Then, the IP address I3 corresponding to the MAC address a1a2, which is different from the source MAC address a3a2 of the packet, is read from the memory 1 of the packet waiting means (not shown), and stored in the memory 2 of the packet waiting means (not shown). Remember. When the destination IP address of the IP packet arriving from the server 20 is I3 stored in the memory 2, the MAC address a1a2 corresponding to the IP address I3 stored in the memory 2 is used as the destination MAC address of the packet. The attached MAC packet is a retransmission packet (in the case of TCP mobile terminal operation) or a retransmission request packet or a communication confirmation packet (in the case of UDP mobile terminal operation) from the mobile terminal side whose MAC address a1a2 is the source MAC address (33 ) Wait in a buffer (not shown) until Mr4r5a1a2 (I0) is received. This is done to prevent the packet of the destination MAC address of the lower address a2 from being erroneously sent out of the ring during clockwise optical ring transfer.

Next, the retransmission packet (29) Mr4r5a1a2 (I0) from the mobile terminal 19-1 is transferred as (30) Mr4r5a1a2 (I0) through the counterclockwise ring 1-1, and the packet add, drop, and pass device 6- 2 shows an example. When the packet arrives at the packet add, drop, and pass device 6-2, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 for designating packet transmission out of the ring. Therefore, the source MAC address a1a2 of the packet is stored in the address table 8 that designates passage of the packet. The packet is forwarded as shown by (31) Mr4r5a1a2 (I0) and arrives at router 22 as shown by (33) Mr4r5a1a2 (I0). As a result, the waiting packet (33) Ma1a2r4r5(I2) is sent from the vertex device 5 to the clockwise ring 1-2 via the upper ring 4, (34) Ma1a2r4r5(I2), (35) Ma1a2r4r5(I2) ), the destination MAC address a1a2 of the packet is stored in the address table 8 that specifies the passage of the packet of the add, drop, and pass devices 6-3 and 6-2 of the packet, so the device , is sent out of the ring by the packet add, drop and pass device 6-1, and arrives at the portable terminal 19-1 (37) as indicated by Ma1a2r4r5 (I2).

The mobile terminal 19-2 shown in the second embodiment moves under the control of the base station 12-2, and the sent packet (25) Mr4r5a3a2 (I0) arrives at the packet add/drop/pass device 6-2. In this case, a copy packet of that packet is sent down the optical ring in a clockwise direction, and when that packet arrives at the packet add, drop, and pass device, the lower address of the source MAC address of that packet is transferred to the packet outside the ring. An operation of deleting from the low-order address memory designating transmission may be added.

Further, in the second embodiment described above, an example is given in which the mobile terminal 19-2 moves through the ring network in the direction of passing base stations in the direction of approaching the server. By the packet immediately after the base station moves, the lower address a2 stored in the lower address memory 7, which designates the packet transmission outside the ring of the packet add, drop and pass device 6-2, is erased. , when a packet with a signal g indicating a packet immediately after movement from the TCP mobile terminal 19-2 immediately after the movement of the base station arrives at the router 22, if the signal p is added to the packet, It is sufficient to operate in the same manner as in the second embodiment. In that case, a packet from the mobile terminal 19-4 under the control of the base station 12-2 arrives at the packet add, drop and pass device 6-2, and is sent to the lower address memory 7 for designating packet transmission out of the ring. When the lower address a2 of the transmission source MAC address of the packet is stored, it is assumed that the transmission source MAC address a1a2 of the terminal 19-1 is stored in the address table 8 for specifying the passage of the packet according to the packet of the mobile terminal. Then, packets addressed to the mobile terminal 19-1 can pass through the device, but packets addressed to the mobile terminal 19-2 cannot pass through the device. Therefore, when a packet arrives at a device for adding, dropping, or passing a packet from outside the ring, the lower address of the transmission source MAC address of the packet is stored in the lower address memory 7 for designating packet transmission outside the ring. or the lower address of the packet transmission source MAC address is stored in the lower address memory 7 that designates packet transmission outside the ring. If the lower address is stored in a state that is not stored, a signal p to that effect is attached to the packet and sent to the router 22, and the router 22 sends a signal p to that effect to the mobile terminal 19- 2 performs the same operation as the packet waiting operation by the packet signal p in the second embodiment in which the base station moves toward the server.

In the above-described embodiment, when the mobile terminal moves between base stations, the lower address of the packet in the lower address memory that designates packet add, drop, and packet transmission outside the ring of the passing device in the packet immediately after movement. The storage of the same low-order address is deleted, but the low-order address deletion may be the deletion of the low-order address only of the device near the add, drop, and passing device of the packet added to the ring network from outside the ring. The elimination of lower order addresses is for eliminating an increase in the number of MAC addresses stored in the address table that designates packet passage due to the movement of the mobile terminal when the equipment for adding, dropping, and passing packets to be added by the mobile terminal moves.

In the above operation, the device for adding, dropping and passing packets does not use the same lower address memory for designating passage of packets as in the first embodiment. Using a multi-round packet discarding device or a loopback bit that is given when an OAM packet arriving from a clockwise ring at the vertex device 5 and a packet at the time of ring failure loops back for the first time and is removed at the second loopback By having the function of blocking the passage of packets other than packets passing through the add, drop and pass devices of all packets and the vertex device through, to the transmission line port on the entrance side of the clockwise ring of the vertex device prepare.

A third embodiment of the present invention will be described with reference to FIG. This embodiment is a tree-like ring network in which a plurality of packet add, drop, and pass devices having an address table that specifies packet passage and a lower address memory that specifies packet transmission outside the ring are connected by optical transmission lines. is an example of handover operation using a ring network that transfers Ethernet packets used for communication between a mobile terminal under the control of a base station and a server. In this embodiment, the gateway device 29 is used, but this device does not have packet waiting means, and the packet waiting means is provided only for the packets directed to the server 20, either in the server 20 or in the router preceding it. 2, otherwise the same as in FIG. The gateway device directs packets destined for the server to the server as MAC packets, and sends voice MAC packets to the exchange function behind the packet waiting means. The exchange functions accept voice packets and perform call and call termination operations.

A fourth embodiment of the present invention will now be described with reference to FIG. This embodiment is a tree-like ring network in which a plurality of packet add, drop, and pass devices having an address table that specifies packet passage and a lower address memory that specifies packet transmission outside the ring are connected by optical transmission lines. is an example of a handover operation using a ring network that transfers Ethernet packets used for communication between a mobile terminal under the control of a base station and a relay station.

In FIG. 4, 6-4, 6-5, and 6-6 are devices for adding, dropping, and passing packets, and the same reference numerals as in FIG. 2 mean the same.

The operation of FIG. 4 will be described below. First, it is assumed that the mobile terminals 19-1, 19-2 and 19-3 already store the IP address I0 of the relay station 26 and the MAC address r4r5 of the ring transmission line interface in their ARP tables. When the mobile terminal 19-1 receives packet (1) Mr4r5a1a2 (I0) (M indicates an Ethernet packet, r4 indicates the upper MAC address of the interface of the relay station 26, r5 indicates the lower MAC address of the interface, a1a2 indicates the lower MAC address of the interface, and a1a2 shows an upper MAC address a1 and a lower MAC address a2, which are the MAC addresses of 1, and I0 indicates the IP address of the destination relay station) is sent to the packet add, drop, and pass device 6-4. . The packet is either a one-way setup packet from the mobile terminal or the base station through which the mobile terminal passes with a period less than or equal to the timer time of the memory address of the memory address of the ring network packet add, drop and pass device, or simply moves. It is a one-way path setting packet at a constant period from the base station through which the terminal or mobile terminal passes, or a location registration packet immediately after changing the base station to the home memory. This eliminates the need for the home memory to store the base station number of the current location of the mobile terminal, and only stores the MAC address of the mobile terminal and the relay station number to which it belongs. However, there are cases where the transit base station number of the mobile terminal is required.
When the packet reaches the packet add/drop/pass device 6-4 from the portable terminal 19-1, the lower address memory designates the packet transmission out of the ring with the lower address a2 of the source MAC address of the packet. Store in 7. The packet is forwarded by (2) Mr4r5a1a2 (I0) on counterclockwise optical ring 1-1, and arrives at packet add, drop, and pass device 6-5.

When the packet (2) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-5, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (3) Mr4r5a1a2 (I0) on the counterclockwise optical ring 1 as shown in the figure, and arrives at the packet add/drop/pass device 6-6. do.

When the packet (3) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-6, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (4) Mr4r5a1a2 (I0) in the counterclockwise optical ring 1 and arrives at the vertex device 5 as it is. The packet is sent out of the ring and reaches relay station 26 via upper ring 3 . The upper rings 3 and 4 have the same configuration as the subscriber system rings 1 and 2 and operate in the same manner.

When the packet (5) Mr4r5a1a2 (I0) arrives at the relay station 26, the relay station server stores the source MAC address a1a2 and the source IP address I2 of the packet in a memory (not shown). Also, the server notifies the home memory 27 that the source terminal of the packet is under the control of the relay station 26 by the source IP address I2 and the MAC address a1a2 of the packet.
Similarly, the packet (6) Mr4r5a3a2 (I0) from the mobile terminal 19-2 is sent to the lower address memory 7 which designates the packet to be sent out of the ring of the packet add, drop and pass device 6-4. The lower address a2 of the original MAC address is stored, transferred through the ring network, and reaches the relay station 26. - 特許庁Similarly, the packet (13) Mr4r5a4a2 (I0) from the portable terminal 19-3 is sent to the lower address memory 7 which designates packet add, drop, and passing device 6-6 to send the packet out of the ring. The lower address a2 of the original MAC address is stored, transferred through the ring network, and reaches the relay station 26. - 特許庁

Next, the mobile terminal 19-1 transmits a call origination packet (15) Mr4r5a1a2 (I0) addressed to the mobile terminal 19-2.
is sent to the packet add, drop and pass device 6-4. When the packet reaches the packet add/drop/pass device 6-4 from the portable terminal 19-1, the lower address memory designates the packet transmission out of the ring with the lower address a2 of the source MAC address of the packet. Store in 7. The packet is forwarded by (16) Mr4r5a1a2 (I0) on counterclockwise optical ring 1-1, and arrives at packet add, drop and pass device 6-5.

When the packet (16) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-5, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is not stored in the memory 7, the packet is forwarded by (17) Mr4r5a1a2 (I0) on the counterclockwise optical ring 1 as shown in the figure, and arrives at the packet add, drop and pass device 6-6. do.

When the packet (17) Mr4r5a1a2 (I0) arrives at the packet add/drop/pass device 6-6, the lower address a2 of the packet transmission source MAC address is the lower address designating the packet transmission out of the ring. Since it is stored in the memory 7, the source MAC address a1a2 of the packet is stored in the address table 8 for designating passage of the packet. The packet is forwarded by (18) Mr4r5a1a2 (I0) on counterclockwise optical ring 1 and arrives at vertex device 5 as shown. The packet is sent out of the ring and reaches relay station 26 via upper ring 3 .

When the packet (18) Mr4r5a1a2 (I0) arrives at the relay station 26, since this packet is a calling packet, an inquiry is made to the home memory 27 using the packet's source IP address I2 and MAC address a1a2, and the destination It obtains the MAC address and IP address of the terminal of the telephone number, recognizes that the destination is under its own relay station, and sends a response incoming packet to the outgoing call packet to the terminal 19-2. A packet copy bit is added to the packet.

A voice incoming packet addressed to terminal 19-2 is sent from relay station 26 via upper ring 3 to clockwise ring 1-2 of subscriber ring 1 as shown by (20) Ma3a2r4r5 (I3).
The destination MAC address a3a2 of the packet (21) Ma3a2r4r5 (I3) transferred through the clockwise ring 1-2 is stored in the address table 8 that specifies the passage of the packet. However, when the destination MAC address a3a2 is not stored in the address table 8 that specifies packet passage, and the lower address a2 of the destination MAC address is stored in the lower address memory 7 that specifies packet transmission outside the ring. If so, copy the packet, send the copy packet out of the ring, and send the original packet forward to the add, drop, and pass devices of the packet. In the figure, at this point in time, the packet add, drop and pass device 6-6 stores the destination MAC address a3a2 in the address table 8 that specifies the packet pass, and the packet add, drop and pass device 6-6. In 5, the destination MAC address a3a2 is not stored in the address table 8 that specifies packet passage, and the lower address a2 of the destination MAC address is stored in the lower address memory 7 that specifies packet transmission outside the ring. In the packet add, drop, and pass device 6-4, the destination MAC address a3a2 is not stored in the address table 8 that specifies packet pass, and the lower address a2 of the destination MAC address is not stored. is stored in the lower address memory 7 that designates packet transmission to the outside of the ring. and the passing device 6-4 copies the packet, sends the copy packet out of the ring by (26) Ma3a2r4r5 (I3) as shown in the figure, and transmits the original packet by (27) Ma3a2r4r5 (I3). to forward packet add, drop and pass devices as shown in .
Packet (26) Ma3a2r4r5 (I3) reaches the destination mobile terminal 19-2.

Next, when the mobile terminal 19-2 moves from the base station 12-1 to the base station 12-2 and the voice packet (28) Mr4r5a3a2 (I0) arrives at the base station 12-2, A signal g indicating the movement of the base station is put in the option area of the IP header of the packet, and sent to the packet add, drop and pass device 6-2. When the packet from the portable terminal 19-2 reaches the add, drop and pass device 6-2, the lower address memory 7 designates the lower address a2 of the source MAC address of the packet to send the packet out of the ring. memorize to The packet is forwarded by (29) Mr4r5a3a2g (I0) on the counterclockwise optical ring 1-1 and reaches the packet add, drop and pass device 6-6.

When the packet (29) Mr4r5a3a2g (I0) arrives at the packet add/drop/pass device 6-6, the packet is a packet that has just moved from the base station, so the lower address a2 of the source MAC address of the packet is is stored in the lower address memory 7 designating packet transmission outside the ring, the stored lower address a2 is erased. In the figure, since the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 that designates packet transmission to the outside of the ring, a horizontal line is drawn to indicate that it has been erased. there is The packet is forwarded by (30) Mr4r5a3a2g (I0) on counterclockwise optical ring 1 and reaches vertex device 5 as shown.

The packet arriving at the vertex device 5 is sent out of the ring and reaches the relay station 26 via the upper ring 3 .

When the packet (31) Mr4r5a3a2g (I0) arrives at the relay station 26, after storing the source MAC address and the source IP address of the packet in a memory (not shown), the packet (31) Mr4r5a3a2g is sent to the base station. However, since it is a voice packet, the packet waiting means is not executed. Even if a packet with the destination MAC address of lower address a2 is erroneously sent out of the ring during clockwise optical ring transfer, the subsequent voice packet from the voice mobile terminal will be sent on the ring network from the relay station to the voice mobile terminal. This is because the route is secured.

Next, an example is shown in which a one-way routing packet (32) Mr4r5a1a2 (I0) from the mobile terminal 19-1 is forwarded through the counterclockwise ring 1-1 and arrives at the packet add, drop and pass device 6-5. . When the packet arrives at the packet add, drop, and pass device 6-5, the lower address a2 of the source MAC address of the packet is stored in the lower address memory 7 for designating packet transmission outside the ring. Therefore, the source MAC address a1a2 of the packet is stored in the address table 8 that designates passage of the packet. The packet is forwarded as shown by (33) Mr4r5a1a2 (I0) and arrives at relay station 26 as shown by (34) Mr4r5a1a2 (I0). As a result, the waiting packet (35) Ma1a2r4r5(I2) is sent from the vertex device 5 to the clockwise ring 1-2 via the upper ring 3, (37) Ma1a2r4r5(I2), (38) Ma1a2r4r5(I2) ), the destination MAC address a1a2 of the packet is stored in the address table 8 that specifies the passage of the packet of the add, drop and pass devices 6-6 and 6-5 of the packet, so the device , is sent out of the ring by the packet add, drop and pass device 6-4, and arrives at the portable terminal 19-1 (39) as indicated by Ma1a2r4r5 (I2).

In the fourth embodiment described above, there are TCP packets with the destination MAC address r1r2 directed to the server 20 and packets with the destination MAC address r4r5 directed to the relay station 26 . In the case of a TCP packet destined for the server 20, the necessary packet is put on standby with the packet trigger immediately after the TCP mobile terminal changes base station. Control of TCP packets communicated between the server 20 and the TCP mobile terminal and control of UDP packets communicated between the relay station 26 and the voice UDP mobile terminal need not be synchronized. This is because voice packets are periodically sent by the call packet sending terminal even when the received packets do not arrive.

Further, the portable terminal 19-2 shown in the second embodiment moves under the control of the base station 12-2, and the sent packet (28) Mr4r5a3a2 (I0) is sent to the packet add/drop/pass device 6-5. When the packet arrives, a copy packet of the packet is sent clockwise downward to the optical ring, and when the packet arrives at the packet add, drop, and pass device, the lower address of the source MAC address of the packet is sent out of the ring. It is also possible to add an operation of deleting from the lower address memory designating the packet transmission of .

In the above four embodiments, when the mobile terminal moves between base stations, the memory address storage of the packet add, drop, and passing packets is deleted in the packet immediately after the movement. This is to reduce the number of MAC addresses stored in the address table, which increases when devices are added, dropped, and passed.

1 Subscriber system counterclockwise optical ring
2 Subscriber system clockwise optical ring 3 Subscriber system ring 4 Upper ring 5 Vertex devices 6-1, 6-2, 6-3, 6-4, 6-5, 6-6 Add, drop and pass packets device 7 lower address memory 8 for specifying packet transmission to outside the ring address table 10 for specifying packet passage lower address memories 12-1, 12-2, 12-3, 12-4, 12-5 Base stations 13-1, 13-2, 13-3, 13-4 Mobile terminal 14 Movement of mobile terminal 20 Server 22 Router 26 Relay station 27 Home memory 29 Gateway device

Claims (7)

A packet in which a loopback bit is inserted and which a base station is accommodated in the lowest ring of a ring network or a tree-like ring network, and a mobile terminal under the base station arrives from a clockwise ring of the ring network or tree-like ring network. and MAC packet communication with a server or relay station via a gateway or router connected to a vertex device that blocks passage of Ethernet frames (registered trademark) (hereinafter referred to as MAC packets) other than OAM packets. A packet transfer system that enables movement between base stations of
When a MAC packet from the mobile terminal via the base station arrives at the packet add, drop, and pass device of the ring network or tree-like ring network,
When the base station gives a signal indicating that the packet is a packet immediately after moving the base station,
Storing the lower address of the source MAC address of the packet in a lower address memory designating packet transmission outside the ring of the device for adding, dropping and passing the packet, and transmitting the packet from the address table designating the passage of the packet. Remove the original MAC address and direct the packet to the server through the vertex device in the left-handed ring, sending the packet out of the ring if the packet reaches the packet add, drop and pass device delete the lower address of the source MAC address of the packet from the lower address memory that specifies the packet, and direct the packet to the server via the vertex device in a counterclockwise ring;
On the other hand, if the packet is not a packet immediately after moving the base station,
The lower address of the source MAC address of the packet is stored in the lower address memory that designates the packet transmission outside the ring of the device for adding, dropping and passing the packet, and the packet is sent to the server via the vertex device in the counterclockwise ring. When the packet arrives at the packet add, drop and pass device, and when the lower address of the source MAC address of the packet is stored in the lower address memory designating the packet transmission out of the ring means for storing the source MAC address of the packet in an address table specifying passage of the packet, and directing the packet to the server via a vertex device in a counterclockwise ring;
When a response incoming packet of a voice call packet from said server or an SMS (Short Message Service) packet or the first incoming packet of FTP arrives at the packet add, drop and pass device in a clockwise ring,
If the destination MAC address of the packet is stored in the address table that specifies the passage of the packet, send the packet toward the packet add, drop, and pass devices ahead of the clockwise ring, and is not stored in the address table that specifies the passage of the packet, and the lower address of the destination MAC address of the packet is stored in the lower address memory that specifies sending the packet out of the ring copy the packet, send the copy packet out of the ring, send the original packet clockwise around the ring to the add, drop, and pass devices of the packet ahead of the ring, and if so, forwarding the packet to a forward packet add, drop and pass device on the clockwise ring;
On the other hand, when a packet other than a response incoming packet of a voice call packet from the server, an SMS (Short Message Service) packet, or the first incoming packet of FTP arrives at the packet add, drop, and pass device in the clockwise ring. ,
If the destination MAC address of the packet is stored in the address table specifying the passage of the packet, send the packet toward the packet add, drop and pass devices ahead of the clockwise ring. , when the destination MAC address of the packet is not stored in an address table that specifies packet passage, and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring; means for sending said packet out of the ring if it is, and for sending said packet clockwise to forward packet add, drop and pass devices in the ring otherwise. prepared,
Means for sending a location registration packet having a source MAC address from a mobile terminal or a base station in use of said mobile terminal, when a passing base station changes or periodically, or a mobile terminal or a base station in use of said mobile terminal means for causing the sending of a unidirectional routing packet having a source MAC address from
means for causing the mobile terminal to send a retransmission packet, a retransmission request packet, or a communication partner confirmation packet to the server when no packet arrives from the server to the mobile terminal for a predetermined time or longer during communication. A packet transfer system that enables mobile terminals to move between base stations.
the device for adding, dropping, and passing packets separately has a lower address memory for designating passing of packets;
when a packet arrives at a device for adding, dropping, and passing packets from the counterclockwise ring, storing a lower address of the source MAC address of the packet in a lower address memory designating passage of the packet;
When a packet arrives at a packet add, drop, and pass device from outside the ring, and if the packet is a packet that has just moved from the base station, the lower address of the source MAC address of the packet is added to the packet. from the lower address memory that specifies the passage of the
When a packet arrives at a packet add, drop, and pass device from the clockwise ring, the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies the pass of the packet, and the 2. Between base stations of mobile terminals according to claim 1, further comprising means for discarding said packet when the lower address of the destination MAC address is not stored in the lower address memory designating packet transmission out of the ring. A packet forwarding system that enables mobility.
A packet waiting means applied to the packet transfer system that enables the mobile terminal to move between base stations according to either claim 1 or claim 2,
The transmission source MAC address of a packet from a mobile terminal to a server or a relay station via a base station, a ring network or a tree-like ring network is set as the own packet of the gateway or router connected to the top device of the ring network or the tree-like ring network. Store the packet in a first memory of the standby means and send the packet to the server or the relay station, or store the source MAC address of the packet directed to the server or the relay station in the optional area of the IP header of the IP packet and send it to the server or relay station,
A packet having a signal indicating that a lower address is not yet stored in a lower address memory designating packet transmission outside the ring of a device for adding, dropping, and passing packets of the ring network is sent to the own packet waiting means. If received by
If a MAC address different from the MAC address having the lower address of the source MAC address of the received packet as a lower address is stored in the first memory of the packet waiting means, the MAC address is stored in the first memory. storing the MAC address in the second memory of its own packet waiting means;
Alternatively, if the first memory of the self-packet waiting means is not used, the source MAC address of the received packet is stored in the second memory of the self-packet waiting means,
In the method that does not use the first memory of the self-packet waiting means, the same lower address as the MAC address stored in the second memory of the self-packet waiting means is assigned to the IP packet of the packet arriving from the server. If the lower address of the MAC address written in the option area of the IP header of is different from the MAC address written in the memory 2, the MAC address is stored in the memory 2, and until the source MAC address of the packet arriving from the terminal side is stored in the second memory of the self-packet waiting means, the packet is sent to the terminal side, and then the self-waiting means waits for the packet. Erasing the MAC address of the same lower address as the MAC address and its lower address stored in the second memory of the means, or
In the method using the first memory of the packet waiting means, when the destination IP address of the IP packet arriving from the server to the own packet waiting means is stored in the second memory of the own packet waiting means , causing the packet to wait until a retransmission request packet or a retransmission packet arrives from the mobile terminal whose source MAC address is the MAC address corresponding to the destination IP address stored in the second memory; when a packet or a retransmission packet arrives, erasing the source MAC address and the source IP address of the retransmission request packet or the retransmission packet from the second memory of the self-packet waiting means;
Packet waiting means characterized by
A wireless section communication method including handover between a base station and a mobile terminal used in the method of moving a mobile terminal between base stations in the packet transfer system according to either claim 1 or claim 2,
When the mobile terminal moves between base stations, if the radio waves from the destination base station become stronger than the radio waves from the base station currently receiving packets, the mobile terminal is sent to the destination base station by CSMA/CA. Secure the specified time slot position of the specified frequency used by the terminal, or secure the CDMA code or OFDM symbol code, and move to the destination base with the secured time slot of the specified frequency or CDMA of that code or OFDM of that code A radio section communication method including handover between a base station and a mobile terminal, characterized by starting communication with a base station.
2. A low-order address memory for designating out-ring packet transmission of a device for adding, dropping, and passing packets of the ring network or tree-like ring network of the packet transfer system according to claim 1, wherein the packet is transmitted out of the ring. Each bit of the parallel data read from the location addressed by the high-order part of the low-order address of the source MAC address and each bit of the parallel data obtained by decoding the low-order part of the low-order address of the source MAC address and By storing the parallel data latch signal of the logical sum of A memory for inserting and storing the lower part as bit 1 at the position of bit 1 of decoding as bit 1 meaning lower address storage,
When deleting the lower address of the source MAC address from the lower address memory that specifies packet transmission outside the ring, the lower address memory that specifies packet transmission outside the ring is replaced with the upper part of the lower address of the source MAC address. Each bit of the parallel data read from the addressed position and the bit-inverted bit of each bit of the parallel data decoded from the lower part of the lower address of the transmission source MAC address are logically ANDed to the outside of the ring. By storing the lower address portion of the lower address of the transmission source MAC address in the address specifying position of the lower address memory designating packet transmission, bit 0 is inserted into the position of decode bit 1 as bit 0 meaning no lower address storage. A low-order address memory for designating packet add, drop, and transmission out of the ring of passing devices of a ring network or a tree-like ring network of a packet transfer system, characterized by storing.
A packet in which a loopback bit is inserted and which a base station is accommodated in the lowest ring of a ring network or a tree-like ring network, and a mobile terminal under the base station arrives from a clockwise ring of the ring network or tree-like ring network. A packet transfer method that enables movement between base stations of a mobile terminal in a network that performs MAC packet communication with a server or relay station via a gateway or router connected to a vertex device that blocks the passage of MAC packets other than OAM packets and OAM packets There is
When a MAC packet from the mobile terminal via the base station arrives at the packet add, drop, and pass device of the ring network or tree-like ring network,
When the base station gives a signal indicating that the packet is a packet immediately after moving the base station,
Storing the lower address of the source MAC address of the packet in a lower address memory designating packet transmission outside the ring of the device for adding, dropping and passing the packet, and transmitting the packet from the address table designating the passage of the packet. Remove the original MAC address and direct the packet to the server through the vertex device in the left-handed ring, sending the packet out of the ring if the packet reaches the packet add, drop and pass device delete the lower address of the source MAC address of the packet from the lower address memory that specifies the packet, and direct the packet to the server via the vertex device in a counterclockwise ring;
On the other hand, if the packet is not a packet immediately after moving the base station,
The lower address of the source MAC address of the packet is stored in the lower address memory that designates the packet transmission outside the ring of the device for adding, dropping and passing the packet, and the packet is sent to the server via the vertex device in the counterclockwise ring. When the packet arrives at the packet add, drop and pass device, and when the lower address of the source MAC address of the packet is stored in the lower address memory designating the packet transmission out of the ring storing the source MAC address of the packet in an address table specifying passage of the packet, and directing the packet to the server via a vertex device in a counter-clockwise ring;
When a response incoming packet of a voice call packet from said server or an SMS (Short Message Service) packet or the first incoming packet of FTP arrives at the packet add, drop and pass device in a clockwise ring,
If the destination MAC address of the packet is stored in the address table that specifies the passage of the packet, send the packet toward the packet add, drop, and pass devices ahead of the clockwise ring, and is not stored in the address table that specifies the passage of the packet, and the lower address of the destination MAC address of the packet is stored in the lower address memory that specifies sending the packet out of the ring copy the packet, send the copy packet out of the ring, send the original packet clockwise around the ring to the add, drop, and pass devices of the packet ahead of the ring, and if so, forwarding the packet to a forward packet add, drop and pass device on the clockwise ring;
On the other hand, when a packet other than a response incoming packet of a voice call packet from the server, an SMS (Short Message Service) packet, or the first incoming packet of FTP arrives at the packet add, drop, and pass device in the clockwise ring. ,
If the destination MAC address of the packet is stored in the address table specifying the passage of the packet, send the packet toward the packet add, drop and pass devices ahead of the clockwise ring. , when the destination MAC address of the packet is not stored in an address table that specifies packet passage, and the lower address of the destination MAC address of the packet is stored in a lower address memory that specifies packet transmission out of the ring; if so, forwarding said packet out of the ring; otherwise, forwarding said packet clockwise around the ring towards forward packet add, drop and pass devices. have
A step of transmitting a location registration packet having a source MAC address from a mobile terminal or a base station in use of said mobile terminal when a passing base station changes or periodically, or a mobile terminal or a base station in use of said mobile terminal. causing the sending of unidirectional routing packets with source MAC addresses from
and a step of causing the mobile terminal to send a retransmission packet, a retransmission request packet, or a communication partner confirmation packet to the server when no packet has arrived from the server to the mobile terminal for a predetermined time or longer during communication. A packet transfer method that enables a mobile terminal to move between base stations.
the device for adding, dropping, and passing packets separately has a lower address memory for designating passing of packets;
when a packet arrives at a device for adding, dropping, and passing packets from the counterclockwise ring, storing a lower address of the source MAC address of the packet in a lower address memory designating passage of the packet;
When a packet arrives at a packet add, drop, and pass device from outside the ring, and if the packet is a packet that has just moved from the base station, the lower address of the source MAC address of the packet is added to the packet. from the lower address memory that specifies the passage of the
When a packet arrives at a packet add, drop, and pass device from the clockwise ring, the lower address of the destination MAC address of the packet is not stored in the lower address memory that specifies the pass of the packet, and the 7. The inter-base-station movement of a mobile terminal according to claim 6, further comprising the step of discarding said packet if the lower address of the destination MAC address is not stored in the lower address memory designating packet transmission out of the ring. A packet forwarding method that allows

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