JP7601816B2 - Transfer device and program - Google Patents

Description

This disclosure relates to technology for continuing communication in an edge computing environment.

In the current cloud computing environment using large aggregated data centers, it is difficult to provide low-latency services. For this reason, Non-Patent Document 1 discloses MEC (Multi-Access Edge Computing), which provides services by distributing many small data centers geographically. In the following, MEC data centers are referred to as MEC sites. Each MEC site is associated with a geographical region (area). For example, the area associated with one MEC site may be an area serviced by one or more base stations. A wireless device (WD) of a mobile communication network is serviced by equipment at an MEC site associated with the area in which the WD is currently located.

In networks that use the current IP protocol, when a communication device starts communication, it obtains the IP address of the communication partner from the DNS. Therefore, when a WD connects to an MEC site, the DNS must notify the WD of the IP address of the device in the MEC site associated with the area in which the WD is currently located. To achieve this, the IP address acquisition process must be modified so that the WD notifies the DNS of location information indicating its location, and the DNS determines the IP address to notify the WD based on the location information.

As a method that does not require changes to the IP address acquisition process, Non-Patent Document 2 discloses a technology called IP Anycast (hereinafter, referred to as the Anycast method). In the Anycast method, the same IP address (hereinafter, a common address) is assigned to all MEC site devices that provide the same service. Therefore, when the WD receives a service provided by the MEC site device, it acquires a common address from DNS regardless of its location. When the WD acquires the common address from DNS, it transmits an IP packet with the common address set as the destination address. When the mobile communication network receives an IP packet with the common address set as the destination address, it transfers the IP packet to the MEC site associated with the area in which the WD is currently located. For example, when the MEC site is associated with one or more base stations, the mobile communication network transfers the IP packet to the MEC site associated with the base station to which the WD is currently connected. Once a connection, such as a TCP connection, is established between the WD and a device in the MEC site, the WD and the device in the MEC site will communicate using the established connection.

S. Kekki, et al. , "MEC in 5G networks", ETSI white paper, vol. 28, pp. 1-28, June 2018 M. Suzuki, et al. , "Enhanced DNS Support towards Distributed MEC Environment", ETSI White Paper No. 39, September 2020

For example, suppose that a WD in a first area is receiving services from a device in a first MEC site, and then the WD moves to a second area associated with a second MEC site. In this case, an IP packet sent by the WD is sent to a device in the second MEC site. Since the device in the second MEC site does not have a connection with the WD, it discards the IP packet it receives from the WD. Therefore, the provision of services to the WD stops.

The present invention provides technology that allows services to be continued even if a wireless device moves to an area associated with a different MEC site.

According to one aspect of the present invention, a forwarding device used in a network that forwards a first packet destined for a common address transmitted by a wireless device to one of a plurality of forwarding devices according to the location of the wireless device includes a holding means for holding a first identifier, and a forwarding means for, when receiving the first packet from the network, determining whether a second identifier included in the first packet matches the first identifier, and, if the second identifier matches the first identifier, forwarding the first packet to one of one or more server devices associated with the forwarding device, and, if the second identifier does not match the first identifier, forwarding a first encapsulated packet in which the first packet is stored in its payload to another forwarding device to which the second identifier is assigned.

According to the present invention, service can be continued even if a wireless device moves to an area associated with a different MEC site.

FIG. 1 is a system configuration diagram according to an embodiment. FIG. 2 is a sequence diagram according to one embodiment. FIG. 2 is a sequence diagram according to one embodiment. FIG. 4 illustrates forwarding information according to one embodiment. FIG. 2 is a configuration diagram of a transfer device according to an embodiment. FIG. 11 is a diagram showing determination information according to an embodiment. FIG. 2 is a sequence diagram according to one embodiment.

The embodiments are described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are necessarily essential to the invention. Two or more of the features described in the embodiments may be combined in any desired manner. In addition, the same reference numbers are used for the same or similar configurations, and duplicate descriptions are omitted.

First Embodiment
FIG. 1 shows a system configuration according to the present embodiment. The MEC site 1 has a transfer device 2 and a plurality of server devices 3. Although FIG. 1 shows two MEC sites 1, the number of MEC sites 1 is any number equal to or greater than two, and the MEC sites 1 are located at various geographical locations. In the following description, when the two MEC sites 1 are to be distinguished from one another, they are referred to as MEC site #1 and MEC site #2. Also, in FIG. 1, the number of server devices 3 located at each MEC site 1 is two, but the number of server devices 3 located at each MEC site 1 can be any number equal to or greater than one. Also, it is not necessary to make the number of server devices 3 located at each MEC site 1 the same. In the following description, when the server devices 3 are to be distinguished from one another, they are referred to as server devices #1-1, #1-2, #2-1, and #2-2, as shown in FIG. 1. Similarly, when the two transfer devices 2 are to be distinguished from one another, they are referred to as transfer devices #1 and #2, as shown in FIG. 1.

In this embodiment, a site identifier is assigned to each MEC site 1. According to FIG. 1, the site identifier of MEC site #1 is ID#1, and the site identifier of MEC site #2 is ID#2. The site identifier is also the device identifier of the transfer device 2 in the same MEC site. The site identifier is set in all devices (transfer device 2 and server device 3) in the same MEC site 1. The site identifier set in the transfer device 2 and the server device 3 to which the same site identifier is set are the server device 3 associated with the transfer device 2.

A server identifier is also assigned to each server device 3. According to FIG. 1, the server identifiers of server devices #1-1, #1-2, #2-1, and #2-2 are SID#1-1, #1-2, #2-1, and #2-2, respectively. The server identifier of the associated server device 3 is set in the transfer device 2. Furthermore, similar to the Anycast method, in this embodiment, a common address AD#C is assigned to the transfer device 2 of each MEC site 1.

Furthermore, each transfer device 2 is assigned a unique address that is a unique address. According to FIG. 1, the unique address of transfer device #1 is AD#1, and the unique address of transfer device #2 is AD#2. Transfer device 2 is connected to network 4. Transfer device 2 is also connected to server device 3 within the same MEC site 1. A unique address is also assigned to each server device 3. The unique address assigned to each server device 3 may be a private address.

WD5 accesses MEC site 1 via a base station (not shown) of the mobile communication network and network 4, and receives services from a server device 3 in MEC site 1. As with the Anycast method, when WD5 accesses MEC site 1, a DNS (not shown) is configured to notify WD5 of the common address AD#C regardless of the location of WD5. In the following description, a packet that WD5 sends to MEC site 1, that is, a packet with the common address AD#C set in the destination address, is referred to as a "MEC packet". Network 4 changes the forwarding destination of the MEC packet depending on the location of WD5. In this embodiment, if WD5 is in area #1, the MEC packet is forwarded to MEC site #1, and if WD5 is in area #2, the MEC packet is forwarded to MEC site #2.

Figure 2 is a sequence diagram when WD5 starts accessing MEC site 1. It is assumed that WD5 is in area #1. When WD5 acquires the common address AD#C from DNS, in S10, it transmits an MEC packet (request MEC packet) for requesting a connection. The request MEC packet is transferred to transfer device #1 of MEC site #1. When transfer device #1 receives the request MEC packet, it selects one of server devices #1-1 and #1-2 and transfers the request MEC packet to the selected server device 3. Note that transfer device 2 has a normal NAT function and converts the common address AD#C set in the destination address of the request MEC packet to the unique address of the selected server device 3. Note that in the following description, the MEC packet whose destination address has been changed by transfer device 2 is also referred to as an MEC packet. According to Figure 2, transfer device #1 selects server device #1-1. Therefore, in S11, transfer device #1 sends a request MEC packet to server device #1-1.

When server device #1-1 receives the request MEC packet, it sets a connection identifier for the connection to be established. In this embodiment, the connection identifier includes a value obtained by concatenating the site identifier ID#1 of MEC site #1 in which server device #1-1 for setting up the connection is installed, and the server identifier SID#1-1 of server device #1-1. For example, the connection identifier can be a value obtained by concatenating the site identifier ID#1 of MEC site #1, the server identifier SID#1-1 of server device #1-1, and a random number in a predetermined order. In response to the request MEC packet, server device #1-1 transmits a response packet to transfer device #1 in S12, which includes the connection identifier and is a packet indicating a response to the request MEC packet. The destination address of the response packet is set to the address of WD5, which is the source address of the request MEC packet.

When the transfer device #1 receives a response packet from the server device #1-1, in S13, it transmits the received response packet to WD5 via the network 4. After the connection between WD5 and the server device #1-1 is established, a connection identifier is set for all packets transmitted and received between WD5 and the server device #1-1. In S14, WD5 transmits an MEC packet containing data (data MEC packet). The transfer device #1 that receives the data MEC packet determines that the transfer destination server device 3 is the server device #1-1 based on the connection identifier (including the server identifier) contained in the data MEC packet. Therefore, in S15, the transfer device #1 transmits the data MEC packet to the server device #1-1. In S16, the server device #1-1 transmits a data packet, which is a packet containing data, to WD5. When the transfer device #1 receives the data packet from the server device #1-1, it transfers it to WD5 (S17).

After that, as long as WD5 is within area #1, communication will take place between WD5 and server device #1-1 as shown in S14 to S17 of Figure 2.

Figure 3 is a sequence diagram when WD5 moves to area #2 while continuing communication with server device #1-1. As WD5 enters area #2, the data MEC packet sent in S20 is forwarded to transfer device #2 in MEC site #2. Based on the connection identifier included in the received data MEC packet, transfer device #2 determines in S21 whether the data MEC packet is addressed to its own site. In this example, the site identifier included in the connection identifier is ID #1, which does not match the site identifier ID #2 of MEC site #2 in which transfer device #2 is installed, so transfer device #2 determines that the received data MEC packet is not addressed to its own site.

In this case, the transfer device #2 transfers the received data MEC packet to the transfer device 2 (in this example, transfer device #1) of the MEC site 1 (in this example, MEC site #1), which is the original destination. Note that encapsulation is used for the transfer. That is, the transfer device #2 generates a new packet, stores the received data MEC packet in the payload of the generated packet, and transmits it to the transfer device 2 of the transfer destination in S22. In the following, a packet that encapsulates another packet is referred to as an encapsulated packet. In order to determine the value to be set in the destination address of the encapsulated packet, each transfer device 2 holds transfer information indicating the relationship between the site identifier and the unique address of the transfer device 2 installed in the MEC site 1 to which the site identifier is assigned for the other MEC sites 1. FIG. 4 shows an example of the transfer information held by the transfer device #2. Based on the transfer information and the site identifier ID#1 included in the received data MEC packet, the transfer device #2 sets the unique address AD#1 of the transfer device #1 to the destination address of the encapsulated packet and transmits it to the network 4.

When transfer device #1 receives an encapsulated packet that includes a data MEC packet in its payload, it extracts the data MEC packet stored in the payload. Then, in S23, transfer device #1 associates the source address of the data MEC packet, that is, the address of WD5, with the source address of the encapsulated packet, that is, AD#2, which is the unique address of transfer device #2 in this example, and registers this in the return information. Also, in S24, transfer device #1 transmits the data MEC packet to server device #1-1 based on the server identifier SID#1-1 included in the extracted data MEC packet.

In S25, server device #1-1 transmits a data packet addressed to WD5 to transfer device #1. When transfer device #1 receives the data packet, in S26, it determines whether the destination address of the data packet is registered in the return information. If it is not registered, transfer device #1 transmits the received data packet to network 4. On the other hand, if it is registered, transfer device #1 encapsulates the received data packet and transmits it to transfer device 2 associated with the destination address of the data packet in the return information. In this example, since the IP address of WD5 is registered in the return information and associated with the unique address AD#2 of transfer device #2, transfer device #1 encapsulates the data packet and transmits it to transfer device #2 in S27. When transfer device #2 receives the encapsulated packet including the data packet, it extracts the data packet and transmits the data packet to WD5 in S28 based on the destination address of the data packet.

With the above configuration, the movement of WD5 allows communication to continue even if the MEC packet is transferred to a different MEC site 1 than before. Note that, although some details are omitted in Figures 2 and 3 for the sake of simplicity, each time the transfer device 2 receives a packet, it determines how to transfer the packet. The method of this determination will be described later.

Figure 5 is a configuration diagram of the transfer device 2. The communication interface 20 is connected to the network 4. The connection interface 21 is connected to the server device 3. When the communication interface 20 and the connection interface 21 receive a packet, they output the received packet to the transfer unit 22. The transfer unit 22 has judgment information and judges the processing for the received packet based on the judgment information. Figure 6 shows the judgment information held by the transfer device #k installed in the MEC site #k. Note that the site identifier of the MEC site #k is ID#k, and the unique address of the transfer device #k is AD#k. Note that, as described above, the site identifier ID#k can also be regarded as the device identifier of the transfer device #k.

First, when the forwarding unit 22 receives a packet whose destination address is the common address AD#C and which has no connection identifier (no site identifier), it determines that the packet should be sent to a server device 3 in the MEC site #k. If multiple server devices 3 are installed in the MEC site #k, the forwarding device #k uses an arbitrary method to select which server device 3 the packet should be sent to. In this case, the forwarding unit 22 outputs the packet to the connection interface 21 together with information indicating the destination server device 3. This process corresponds to S10 and S11 in FIG. 2.

When the forwarding unit 22 receives a packet whose destination address is the common address AD#C and whose site identifier in the connection identifier is ID#k, the forwarding unit 22 determines to transmit the packet to the server device 3 of the MEC site #k indicated by the server identifier in the connection identifier. In this case, the forwarding unit 22 outputs the packet to the connection interface 21 together with information indicating the destination server device 3. Note that this process corresponds to S14 and S15 in FIG. 2.

When the forwarding unit 22 receives a packet whose destination address is the common address AD#C and whose site identifier in the connection identifier is different from ID#k, it determines that the packet should be encapsulated and transmitted to the network 4. In this case, the forwarding unit 22 causes the encapsulation processing unit 23 to encapsulate the received packet. That is, it causes the encapsulation processing unit 23 to generate an encapsulated packet. In the following description, the packet stored in the payload of the encapsulated packet is referred to as the encapsulated packet. The forwarding unit 22 determines the value to be set in the destination address of the encapsulated packet by referring to the forwarding information using the site identifier. The forwarding unit 22 transmits the encapsulated packet to the communication interface 20. Note that this process corresponds to S20 to S22 in FIG. 3.

When the forwarding unit 22 receives an encapsulated packet whose destination address is the unique address AD#k, it determines that the encapsulated packet should be decapsulated. In this case, the forwarding unit 22 causes the encapsulation processing unit 23 to decapsulate the received encapsulated packet. In other words, it causes the encapsulation processing unit 23 to extract the encapsulated packet stored in the payload of the encapsulated packet. Next, the processing for the encapsulated packet is determined again based on the determination information. This processing corresponds to the processing of S22 to S24 and S27 and S28 in FIG. 3. Note that, as shown in S23 in FIG. 3, when the forwarding unit 22 transmits an encapsulated packet to the server device 3, it registers the correspondence between the source address of the encapsulated packet and the source address of the encapsulated packet in the return information. Note that, when the forwarding unit 22 receives a packet whose destination address is the unique address AD#k but which is not an encapsulated packet, it performs normal packet processing.

When the forwarding unit 22 receives a packet whose destination address is different from the common address AD#C and the unique address AD#k and which is not registered in the return information, the forwarding unit 22 performs normal forwarding processing on the packet according to the destination address of the packet. In this case, the forwarding unit 22 transmits the received packet to the interface corresponding to the destination address. This processing corresponds to S16 and S17 in FIG. 2.

When the forwarding unit 22 receives a packet from the server device 3 of the MEC site #k, the destination address of which is different from the common address AD#C and the unique address AD#k, and the destination address is registered in the return information, the forwarding unit 22 determines to encapsulate the packet and transmit it to the network 4. In this case, the forwarding unit 22 causes the encapsulation processing unit 23 to encapsulate the received packet. The forwarding unit 22 determines the value to be set in the destination address of the encapsulated packet by referring to the return information using the destination address of the packet to be encapsulated. The forwarding unit 22 transmits the encapsulated packet to the communication interface 20. Note that this process corresponds to S25 to S27 in FIG. 3.

In the embodiment described above, the common address AD#C and a unique address are assigned to the transfer device 2, and only a unique address is assigned to each server device 3. However, it is also possible to configure the common address AD#C and a unique address to be assigned to each server device 3, and only a unique address to each transfer device 2. Even in this case, each MEC site 1 is configured so that packets are sent and received between the network 4 and each server device 3 via the transfer device 2 of the same MEC site 1. In this case, the transfer device 2 does not perform NAT. By doing so, communication can be performed as described in Figures 1 to 6.

Second Embodiment
Next, the second embodiment will be described with a focus on differences from the first embodiment. In the sequence of FIG. 3, unless WD5 returns to area #1, the communication between WD5 and server device #1-1 will go through another MEC site 1, and the delay will increase. Therefore, in this embodiment, when the transfer device #1 receives the encapsulated data MEC packet from the MEC site #2 in S22, it notifies the server device #1-1 that the communication is being performed through the transfer device #2 of the MEC site #2. This notification includes, for example, the unique address of the transfer device #2. For example, the transfer device #1 can perform the notification by using the header area of the data MEC packet of S24. In addition, the transfer device #1 can individually notify the server device #1-1 that the communication with WD5 is being performed through the transfer device #2 of the MEC site #2.

In response to this notification, server device #1-1 can send a request to transfer service provision to WD5 to MEC site #2. Figure 7 is a sequence diagram of the process in which server device #1-1 transfers service provision to WD5 to MEC site #2. Note that in Figure 7, the dotted arrows indicate the process in which server device #1-1 hands over the role of service provision to MEC site #2, and the solid arrows indicate the process in which server device #1-1 notifies WD5 of a change in the connection identifier.

In S30, server device #1-1 transmits a takeover request packet, which is a packet requesting a takeover to MEC site #2. The destination of the takeover request packet is, for example, the unique address of transfer device #2 notified by transfer device #1 in the notification. The takeover request packet includes the unique address of server device #1-1. In S31, transfer device #1 transfers the takeover request packet to transfer device #2. When transfer device #2 receives the takeover request packet, it selects a server device 3 that will take over the provision of the service from server device #2-1 and #2-2. In FIG. 7, transfer device #2 selects server device #2-2. Therefore, transfer device #2 transmits a newly generated takeover request packet to server device #2-2 in S32. The unique address of server device #1-1 is included in this newly generated takeover request packet. Server device #2-2 sends a response packet to server device #1-1 based on the unique address of server device #1-1 included in the takeover request packet, and obtains information necessary for providing services from server device #1-1. For example, if WD5 is receiving video data distribution, it obtains information for identifying undistributed data. Server device #2-2 also generates a connection identifier, that is, a value that combines the site identifier ID#2 of MEC site #2, the server identifier #2-2 of server device #2-2, and a random number, and notifies server device #1-1 of this value during the processing of S33.

When the takeover is completed, the server device #1-1 generates an identifier switching notification packet notifying that the connection identifier will be changed. In addition to the previous connection identifier, the identifier switching notification packet includes the connection identifier to be used in future communications with WD5, that is, the connection identifier generated by the server device #2-2 and notified to the server device #1-1. In S34, the server device #1-1 transmits an identifier switching notification packet with the destination set to WD5 to the transfer device #1. The transfer device #1 encapsulates the identifier switching notification packet and transmits it to the transfer device #2 (S35), and the transfer device #2 transmits the identifier switching notification packet included in the encapsulated packet to WD5 (S36). As a result, WD5 includes a connection identifier including the site identifier ID#2 of the MEC site #2 and the server identifier SID#2-2 of the server device #2-2 in the subsequent MEC packet. As a result, the MEC packet is transmitted from the transfer device #2 to the server device #2-2. In addition, when transfer device #1 sends an identifier switching notification packet to WD5, it deletes the return information entry for WD5.

With the above configuration, even if the MEC packet is transferred to a different MEC site 1 due to the movement of WD5, communication can be continued and an increase in communication delay can be suppressed.

In the above embodiments, the transfer device 2 is connected to one or more associated server devices 3. However, it is sufficient that packets can be transmitted and received between the transfer device 2 and the one or more associated server devices 3, and the transfer device 2 does not need to be directly connected to the one or more associated server devices 3.

The transfer device 2 according to the present disclosure can be realized by a program that causes a computer to operate as the transfer device 2. The program is configured to cause a device having one or more processors to function as the transfer device 2 when executed by the device. The program can be stored in a computer-readable storage medium or distributed via a network.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the invention.

With the above configuration, it is possible to continue providing services even if the wireless device moves to an area associated with a different MEC site. This makes it possible to contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

22: Transfer section

Claims (11)

A forwarding device used in a network that forwards a first packet having a common address sent by a wireless device to one of a plurality of forwarding devices according to a location of the wireless device, the forwarding device comprising:
A storage means for storing a first identifier;
a forwarding means for receiving the first packet from the network, determining whether a second identifier included in the first packet matches the first identifier, and if the second identifier matches the first identifier, forwarding the first packet to one of one or more server devices associated with the forwarding device, and if the second identifier does not match the first identifier, forwarding a first encapsulated packet having the first packet stored in its payload to another forwarding device to which the second identifier is assigned;
A transfer device comprising: The forwarding device according to claim 1, wherein, if the second identifier matches the first identifier, the forwarding means forwards the first packet to a server device, among the one or more server devices, to which the server identifier included in the first packet is assigned. The forwarding device according to claim 1 or 2, wherein if the first packet does not include the second identifier, the forwarding means forwards the first packet to one server device selected from the one or more server devices. the forwarding means holds forwarding information indicating a correspondence between a unique address assigned to each of the plurality of forwarding devices and the second identifier;
4. The forwarding device according to claim 1, wherein if the second identifier does not match the first identifier, the forwarding means forwards the first encapsulated packet to the other forwarding device by setting a unique address corresponding to the second identifier as the destination address of the first encapsulated packet and sending it to the network. The forwarding device according to claim 4, wherein, when a second encapsulated packet is received in which a unique address assigned to the forwarding device from the network is set as the destination and the second packet is stored in the payload, the forwarding means forwards the second packet to a server device to which the server identifier included in the second packet is assigned, among the one or more server devices, if the common address is set as the destination of the second packet and the second identifier included in the second packet matches the first identifier. The forwarding device according to claim 5, wherein the forwarding means notifies a server device to which a server identifier included in the second packet is assigned that the second packet has been received from another forwarding device. The forwarding device according to claim 5 or 6, wherein, if the common address is not set as the destination of the second packet, the forwarding means forwards the second packet to a device to which the address set as the destination of the second packet is assigned. The forwarding device according to any one of claims 5 to 7, wherein the forwarding means, when forwarding the second packet to a server device to which a server identifier included in the second packet is assigned, holds, as return information, a correspondence between the first source address of the second encapsulated packet and the second source address of the second packet. The transfer device according to claim 8, wherein, when a third packet is received from one of the one or more server devices, the transfer means determines whether or not the address set as the destination of the third packet matches the second source address of the return information, and if the address set as the destination of the third packet does not match the second source address of the return information, transfers the third packet to a device to which the address set as the destination of the third packet is assigned. The forwarding device according to claim 9, wherein, when the address set as the destination of the third packet matches the second source address of the return information, the forwarding means stores the third packet in a payload and transmits to the network a third encapsulated packet having the first source address, which is indicated in the return information as corresponding to the second source address, set as the destination. A program characterized in that, when executed by one or more processors of a device having one or more processors, the device functions as a transfer device according to any one of claims 1 to 10.

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