Non-intrusive multicast forwarding method and system of cloud platform

Abstract

The application provides a non-intrusive multicast forwarding method and system of a cloud platform, belongs to the field of cloud computing and the field of computer networks, and exists in two virtual interfaces. The virtual interface 1 belongs to the VPC, and the virtual interface 2 belongs to the vlan network. The vlan network can be interconnected with an external core switch. The multicast message received by the device is detected for the multicast destination address and the source address, the multicast message is sent to the core switch in the gre tunnel mode or the vlan mode according to the configuration option (the mode selection is configured in the initial stage), and the source IP address of the message is modified to the IP address of the interface 2. The core switch supports the multicast protocol, so that the message can be forwarded to the multicast receiver according to the multicast table item, and the forwarding of the multicast message is completed.

Description

Technical Field

[0001] This invention relates to the fields of cloud computing and computer networks, and in particular to a non-intrusive multicast forwarding method and system for cloud platforms. Background Technology

[0002] In traditional network communication, there are three data transmission methods. The first is unicast, which establishes a point-to-point network connection between the sender and each receiver. If a sender transmits the same data to multiple receivers simultaneously, multiple copies of the same data packet must be made. If a large number of hosts want to receive the same copy of the data packet, it will lead to a heavy burden on the sender, long latency, and network congestion; to ensure a certain quality of service, hardware and bandwidth need to be increased. The second is broadcast, which broadcasts data packets within an IP subnet, and all hosts within the subnet will receive these data packets. Broadcast means that the network delivers a data packet to every host in the subnet, regardless of whether these hosts want to receive the data packet. Therefore, the scope of broadcast is very small, only effective within the local subnet, and broadcast transmission is controlled by routers and network devices. The third is multicast, which establishes a point-to-multipoint network connection between the sender and each receiver. If a sender transmits the same data to multiple receivers simultaneously, only one copy of the same data packet needs to be made. It improves data transmission efficiency and reduces the possibility of backbone network congestion, so multicast is widely used in network services such as video, audio, and multimedia conferencing.

[0003] Currently, in cloud computing platforms, such as OpenStack and Kubernetes, the OpenStack network component Neutron does not support multicast functionality. Furthermore, the host machine hosting the cloud platform may not have multicast routing enabled, and the underlying technology does not support dynamic multicast protocols. When the multicast source is deployed within a VPC, which has various network configurations, multicast packets cannot be sent to external core switches and thus to multicast receivers via the VPC virtual router when the VPC network type is VXLAN or Geneve.

[0004] If the cloud platform has already been deployed, developing a new multicast protocol based on the cloud platform requires modifying the platform's basic modules, changing the processing logic of the virtual routers within the VPC, and upgrading the cloud platform, which will affect users of the platform. Therefore, it is necessary to develop a completely new forwarding device that utilizes the existing resources of the cloud platform, without upgrading the basic components, and deploys only a single function to support multicast forwarding.

[0005] Currently, VPCs within the cloud platform support multiple network types. When a multicast source is deployed within a VPC, the multicast source network type is also deployed according to the actual needs of the customer. When interfacing with external core switches, it is necessary to ensure that the external core switches are unaware of the VPC network type and do not require additional configuration to register the multicast source. Summary of the Invention

[0006] To address the above technical issues, this invention provides a non-intrusive multicast forwarding method for cloud platforms. This method achieves multicast forwarding by creating a new virtual machine within the VPC of the cloud platform as a multicast forwarding device, without intruding into the virtual router within the VPC.

[0007] The technical solution of this invention is:

[0008] A non-intrusive multicast forwarding method for a cloud platform has two virtual interfaces: virtual interface 1 belongs to the VPC, and virtual interface 2 belongs to the VLAN network. This VLAN network can communicate with an external core switch. The device detects the multicast destination and source addresses of received multicast packets and, according to the configuration options, forwards the multicast packets to the core switch in either GRE tunnel mode or VLAN mode (mode selection is configured in the initial stage). At the same time, the source IP address of the packet is modified to the IP address of interface 2. If the core switch supports the multicast protocol, it can forward the packets to the multicast receivers according to the multicast table entries, thus completing the forwarding of the multicast packets.

[0009] Furthermore,

[0010] When deployed within a VPC, multicast traffic within the VPC is forwarded across subnets via multicast forwarding.

[0011] Monitor the virtual machine IP address and status, issue rules when requirements are met, route and forward multicast packets sent by the virtual machine, and clean up the relevant forwarding rules when the virtual machine status changes.

[0012] Perform NAT translation on the source address to prevent the core switch from not recognizing the virtual machine address and being unable to add it to the multicast routing table.

[0013] Depending on the configured network mode, multicast packets are sent to the VLAN network or GRE tunnel to ensure that multicast packets can be delivered to the core switch that supports multicast routing.

[0014] This invention also provides a non-intrusive multicast forwarding system for a cloud platform, comprising the following components: 1) a northbound interface; 2) a configuration database; 3) a platform management component; and 4) a multicast forwarding device.

[0015] in,

[0016] 1) Northbound Interface: Provides a series of RESTful interfaces for cloud computing management platforms or third-party platforms to create, delete, and view multicast forwarding devices;

[0017] 2) Configure the database: Used to record information related to user creation;

[0018] 3) Platform management components: used to create multicast forwarding device resources;

[0019] 4) Multicast forwarding device: filters multicast source packets, forwards legitimate multicast packets, and performs NAT conversion on multicast packets and forwards them according to the configured network type.

[0020] Furthermore,

[0021] 1) Deploy a multicast forwarding device within the cloud platform. The device is deployed inside the VPC as a core functional component; Virtual Interface 1 belongs to this VPC network.

[0022] 2) The multicast forwarding device has another virtual interface deployed in a VLAN network, which can directly communicate with the external core router;

[0023] 3) Multicast forwarding device: Open the multicast rules in the port security group of this device to receive multicast packets sent by virtual machines in this VPC.

[0024] 4) After receiving the multicast message, the multicast forwarding device converts the source address of the multicast message to the IP address of virtual interface 2 according to the rules configured locally.

[0025] 5) The device adds a VLAN tag to multicast packets or forwards them through a GRE tunnel to the core switch, i.e., the multicast router;

[0026] 6) After receiving the multicast source registration message, the core switch registers according to the multicast configuration and finally forwards the multicast message to the multicast receiver.

[0027] 7) Multicast forwarding device: monitors the status and IP address of virtual machines within this VPC, and only forwards multicast packets from active virtual machines to prevent abnormal packets from impacting the core router.

[0028] Furthermore,

[0029] Control plane execution process

[0030] The specific process for a user to create a multicast forwarding device is as follows:

[0031] 1) Users create multicast forwarding devices by calling the northbound interface on the cloud platform through the interface. Users need to input parameters including: forwarding mode, i.e., VLAN or GRE. If it is GRE, remote IP and multicast group IP network segment need to be configured.

[0032] 2) The northbound interface records the configuration information into the configuration database;

[0033] 3) The platform management component calls the virtual machine creation interface to create a virtual machine under the VPC using the image of the multicast forwarding device. The virtual machine acts as a multicast forwarding device, creating two virtual network cards. One of them is connected to the VPC, and the other is connected to the VLAN network to communicate with the switch. The relevant security group rules are opened.

[0034] 4) The multicast forwarding device obtains configuration information, including network type, multicast group address, and GRE tunnel remote IP;

[0035] 5) The multicast forwarding device allows packets sent by active virtual machines within the VPC to pass through this multicast device based on the virtual machine status and IP address.

[0036] 6) Rules issued by the multicast forwarding device, including NAT translation rules, VLAN network rules, or GRE tunnel rules;

[0037] 7) After detecting changes in a virtual machine within the VPC, the multicast forwarding device clears the rules related to that virtual machine.

[0038] Furthermore,

[0039] Data plane execution process

[0040] Multicast source virtual machine and multicast forwarding device on the same physical server process

[0041] 1) Virtual machines within the VPC act as multicast sources, sending multicast packets to the virtual switch;

[0042] 2) After receiving the multicast message, the cloud platform virtual machine switch will forward the multicast message in the Layer 2 domain and forward the message to the multicast forwarding device.

[0043] 3) After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, the packet is NAT-translated and forwarded to the core switch through the VLAN network.

[0044] 4) The core switch forwards the packets to the actual multicast receivers according to the device's multicast routing table.

[0045] Furthermore,

[0046] Data plane execution process

[0047] The multicast source virtual machine and the multicast forwarding device are not on the same physical server for forwarding processes.

[0048] 1) Virtual machines within the VPC act as multicast sources, sending multicast packets to the virtual switch;

[0049] 2) After receiving the multicast packet, the cloud platform virtual machine switch will forward the multicast packet in the Layer 2 domain, and send the packet to compute2 after adding encapsulation.

[0050] 3) After receiving the packet, the Compute2 virtual switch decapsulates it and sends the packet to the multicast forwarding device;

[0051] 4) After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, the packet is NAT translated and forwarded to the core switch through the virtual interface 2.

[0052] 5) The core switch forwards the packets to the actual multicast receivers according to the device's multicast routing table.

[0053] Furthermore,

[0054] Data plane execution process

[0055] The multicast source virtual machine and the multicast forwarding device are not on the same physical server, and the network type is configured as GRE mode.

[0056] If the switches in the cloud platform do not support multicast routing, a multicast forwarding device is needed to send the packets to the remote core switch, and the core switch acts as a multicast router to forward the packets.

[0057] 1) Virtual machine VM1 within the VPC acts as a multicast source, sending multicast packets to the virtual switch;

[0058] 2) After receiving the multicast packet, the cloud platform virtual machine switch will forward the multicast packet in the Layer 2 domain, and send the packet to compute2 after adding encapsulation.

[0059] 3) After receiving the packet, the Compute2 virtual switch decapsulates it and sends the packet to the multicast forwarding device;

[0060] 4) After receiving the packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they meet the rules, it performs NAT translation on the packet, converts it to the address of the virtual interface 2, and performs GRE encapsulation on the packet, encapsulating the remote IP as the core switch IP address.

[0061] 5) The switches within the platform forward the packets to the core switch;

[0062] 6) After receiving the packet, the core switch decapsulates the packet, adds the packet to the multicast group, and forwards it to the multicast receiver.

[0063] Furthermore,

[0064] The VPC network is a VLAN network, but the switch in the VLAN network where the VPC resides supports multicast functionality.

[0065] In this scenario, no multicast forwarding device is required. When a virtual machine in the VPC sends a message, it is sent to the physical switch via the VLAN network. The switch supports multicast forwarding and registers the message in the multicast table, thus enabling the multicast message to be forwarded to the multicast receiver.

[0066] Furthermore,

[0067] The VPC network is a VLAN network, but the switch in the VLAN network where the VPC resides does not support multicast functionality.

[0068] 1) Virtual machines within the VPC act as multicast sources, sending multicast packets to the physical switch;

[0069] 2) After receiving a multicast message, the physical switch will forward the multicast message within the Layer 2 domain and send the message to the multicast forwarding device on compute2.

[0070] 3) After receiving the packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they meet the rules, the packet is NAT translated to the address of the virtual interface 2, and then GRE encapsulated into the packet to encapsulate the remote IP as the core switch IP address.

[0071] 4) The switches within the platform forward the packets to the core switch;

[0072] 5) After receiving the packet, the core switch decapsulates the packet, adds the packet to the multicast group, and forwards it to the multicast receiver.

[0073] The beneficial effects of this invention are

[0074] Without intruding into the virtual router within the VPC, it is possible to forward multicast routes between multicast sources within the cloud platform and external core switches (multicast routers).

[0075] Through the multicast forwarding device, the core switch outside the platform does not need to be aware of the VPC network type and changes in network type;

[0076] With the intelligent gateway forwarding device, when the switches in the cloud platform do not support multicast routing, they can communicate with the remote core switch through tunnel mode to achieve multicast routing forwarding to the core switch.

[0077] 4) The cloud platform does not require upgrades or modifications. It can achieve multicast routing function simply by installing a new plugin, and can communicate with the external core switch (multicast router) as a multicast source. Attached Figure Description

[0078] Figure 1 This is a control plane architecture diagram of the multicast forwarding device;

[0079] Figure 2This is the execution flowchart of the control platform for the multicast forwarding device;

[0080] Figure 3 This is a flowchart showing the process of having the multicast source virtual machine and the multicast forwarding device on the same physical server.

[0081] Figure 4 This is a flowchart illustrating the forwarding process when the multicast source virtual machine and the multicast forwarding device are not on the same physical server.

[0082] Figure 5 The multicast source virtual machine and the multicast forwarding device are not on the same physical server, and the network type is configured as GRE mode (flowchart).

[0083] Figure 6 This is a flowchart illustrating the process of handling a VPC network that is a VLAN network, but the switch in the VLAN network where the VPC is located does not support multicast functionality. Detailed Implementation

[0084] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0085] This invention implements multicast routing forwarding functionality by creating new virtual machine (container) resources under a VPC on a cloud platform, including:

[0086] 1) Deploy a multicast forwarding device within the cloud platform, specifically within a VPC, as a core functional component; Virtual Interface 1 belongs to this VPC network. 2) Another virtual interface of the multicast forwarding device is deployed within a VLAN network, which can directly communicate with the external core router. 3) Enable the multicast rules in the port security group of the multicast forwarding device to receive multicast packets from virtual machines within this VPC. 4) Upon receiving a multicast packet, the multicast forwarding device converts the source address of the multicast packet to the IP address of Virtual Interface 2 according to the locally configured rules. 5) The device adds VLAN tags to the multicast packets. 6) After receiving the multicast source registration message, the core switch can register according to the multicast configuration because the address of the VLAN network used by the multicast forwarding device has a VLAN subnet with the core switch, and finally forward the multicast message to the multicast receiver; 7) The multicast forwarding device listens to the status and IP address of the virtual machines in this VPC, and only forwards multicast messages from active virtual machines to prevent abnormal messages from impacting the core router;

[0087] The basic implementation architecture of this technical solution is as follows: Figure 1 As shown, it mainly includes the following components: 1) Northbound interface; 2) Configuration database; 3) Platform management component; 4) Multicast forwarding device.

[0088] Northbound interface: Provides a series of RESTful interfaces for cloud computing management platforms or third-party platforms to create, delete, and view multicast forwarding devices.

[0089] Platform management component: Used to create multicast forwarding device resources.

[0090] Configuration database: Used to record information related to user creation.

[0091] Multicast forwarding device: filters multicast source packets, forwards legitimate multicast packets, and performs NAT conversion on multicast packets and forwards them according to the configured network type.

[0092] The following is in conjunction with the appendix Figure 2-6 The present invention will be further described below.

[0093] Note: The default core switch is the multicast router.

[0094] Control plane execution process

[0095] Taking a user-created multicast forwarding device as an example, such as Figure 2 As shown, the specific process is as follows:

[0096] Users create multicast forwarding devices by calling the northbound interface on the cloud platform through the interface. Users need to input parameters including: forwarding mode (vlan or gre). If it is gre, the remote IP and the multicast group IP network segment need to be configured.

[0097] The northbound interface records the configuration information into the configuration database;

[0098] The platform management component calls the virtual machine creation interface to create a virtual machine under the VPC using the image of the multicast forwarding device. The virtual machine acts as a multicast forwarding device, creating two virtual network interfaces. One of them is connected to the VPC, and the other is connected to the VLAN network to communicate with the switch. The relevant security group rules are opened.

[0099] The multicast forwarding device obtains configuration information, including network type, multicast group address, and GRE tunnel remote IP.

[0100] The multicast forwarding device allows packets sent by active virtual machines within the VPC to pass through this multicast device based on the virtual machine status and IP address.

[0101] Multicast forwarding devices issue rules, including NAT translation rules, VLAN network rules, or GRE tunnel rules;

[0102] After detecting changes to virtual machines within the VPC, the multicast forwarding device clears the rules related to that virtual machine.

[0103] Data plane execution process

[0104] Multicast source virtual machine and multicast forwarding device on the same physical server process

[0105] like Figure 3 As shown, virtual machine VM1 in the VPC (VXLAN network type) sends multicast packets to the virtual switch as a multicast source;

[0106] After receiving a multicast message, the cloud platform virtual machine switch will forward the multicast message within the Layer 2 domain and forward the message to the multicast forwarding device.

[0107] After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, it performs NAT translation on the packet and forwards the packet to the core switch through the VLAN network.

[0108] The core switch forwards packets to the actual multicast receivers based on the device's multicast routing table.

[0109] The multicast source virtual machine and the multicast forwarding device are not on the same physical server for forwarding processes.

[0110] like Figure 4 As shown, virtual machine VM1 in the VPC (VXLAN network type) sends multicast packets to the virtual switch as a multicast source;

[0111] After receiving a multicast packet, the cloud platform virtual machine switch will forward the multicast packet within the Layer 2 domain, and send the packet to compute2 after adding encapsulation.

[0112] After receiving the packet, the Compute2 virtual switch decapsulates it and sends it to the multicast forwarding device.

[0113] After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, it performs NAT translation on the packet and forwards the packet to the core switch through the virtual interface 2 (VLAN network).

[0114] The core switch forwards packets to the actual multicast receivers based on the device's multicast routing table.

[0115] The multicast source virtual machine and the multicast forwarding device are not on the same physical server, and the network type is configured as GRE mode.

[0116] There may be a situation where the switches within the cloud platform do not support multicast routing. Therefore, a multicast forwarding device is needed to send packets to the remote core switch, which then acts as a multicast router to forward the packets.

[0117] like Figure 5 As shown, virtual machine VM1 in the VPC (VXLAN network type) sends multicast packets to the virtual switch as a multicast source;

[0118] After receiving a multicast packet, the cloud platform virtual machine switch will forward the multicast packet within the Layer 2 domain, and send the packet to compute2 after adding encapsulation.

[0119] After receiving the packet, the Compute2 virtual switch decapsulates it and sends it to the multicast forwarding device.

[0120] After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, it performs NAT translation on the packet, converts it to the address of the virtual interface 2, and then performs GRE encapsulation on the packet, encapsulating the remote IP as the core switch IP address.

[0121] The platform's internal switches forward packets to the core switch;

[0122] After receiving the packet, the core switch decapsulates the packet, adds it to the multicast group, and forwards it to the multicast receiver.

[0123] The VPC network is a VLAN network, but the switch in the VLAN network where the VPC resides supports multicast functionality.

[0124] In this scenario, no multicast forwarding device is required. When a virtual machine in the VPC sends a message, it is sent to the physical switch via the VLAN network. The switch supports multicast forwarding and registers the message in the multicast table, thus enabling the multicast message to be forwarded to the multicast receiver.

[0125] The VPC network is a VLAN network, but the switch in the VLAN network where the VPC resides does not support multicast functionality.

[0126] like Figure 6 As shown, VM1 within the VPC (VLAN network type) acts as a multicast source, sending multicast packets to the physical switch.

[0127] After receiving a multicast message, the physical switch will forward the multicast message within the Layer 2 domain and send the message to the multicast forwarding device on compute2.

[0128] After receiving a packet, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address. If they match the rules, it performs NAT translation on the packet, converts it to the address of the virtual interface 2, and then performs GRE encapsulation on the packet, encapsulating the remote IP as the core switch IP address.

[0129] The platform's internal switches forward packets to the core switch;

[0130] After receiving the packet, the core switch decapsulates the packet, adds it to the multicast group, and forwards it to the multicast receiver.

[0131] The above description is merely a preferred embodiment of the present invention and is used only to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A non-intrusive multicast forwarding method of a cloud platform, characterized in that, a user creates a multicast forwarding device, and the specific process is as follows: 1) The user creates a multicast forwarding device through a northbound interface on the cloud platform, and needs to input parameters including: forwarding mode, i.e., vlan or gre, if it is gre, the remote IP needs to be configured, and the multicast group IP network segment; 2) The northbound interface records the configuration information in the configuration database; 3) The platform management component calls a virtual machine creation interface to create a virtual machine using the image of the multicast forwarding device under the VPC, the virtual machine serves as the multicast forwarding device, and two virtual network cards are created, one of which accesses the VPC, and the other accesses the vlan network and interworks with the switch; 4) The multicast forwarding device obtains the configuration information, including the network type, the multicast group address, and the GRE tunnel remote IP; 5) The multicast forwarding device allows the messages sent by the activated virtual machines in the VPC to pass through the multicast device according to the virtual machine state and IP address; 6) The multicast forwarding device issues rules, including NAT conversion rules, vlan network or GRE tunnel rules; 7) After listening to the virtual machine changes in the VPC, the multicast forwarding device clears the rules related to the virtual machine; The process of the multicast source virtual machine and the multicast forwarding device in the same physical server is as follows: 1) The virtual machine in the VPC as a multicast source sends multicast messages to the virtual switch; 2) After receiving the multicast messages, the cloud platform virtual machine switch forwards the multicast messages in the second layer domain, and forwards the messages to the multicast forwarding device; 3) After receiving the messages, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address, and converts the messages through the VLAN network after the rules are met, and forwards the messages to the core switch; 4) The core switch forwards the messages to the actual multicast receiver according to the multicast routing table of the device. 2.A method according to claim 1, characterized in that, The process of the multicast source virtual machine and the multicast forwarding device not in the same physical server is as follows: 1) The virtual machine in the VPC as a multicast source sends multicast messages to the virtual switch; 2) After receiving the multicast messages, the cloud platform virtual machine switch forwards the multicast messages in the second layer domain, and sends the encapsulated messages to compute2; 3) After receiving the messages, the compute2 virtual switch sends the messages to the multicast forwarding device after decapsulating; 4) After receiving the messages, the virtual interface 1 of the multicast forwarding device detects the multicast source address and the multicast destination address, and converts the messages through the virtual interface 2 after the rules are met, and forwards the messages to the core switch; 5) The core switch forwards the messages to the actual multicast receiver according to the multicast routing table of the device. 3.A method according to claim 2, characterized in that, The process of the multicast source virtual machine and the multicast forwarding device not in the same physical server is as follows: If the switch in the cloud platform does not support multicast routing function, the multicast forwarding device needs to send the messages to the remote core switch, and the core switch serves as a multicast router to forward the messages; 1) The virtual machine VM1 in the VPC as a multicast source sends multicast messages to the virtual switch; 2) The cloud platform virtual machine switch receives the multicast message and forwards the multicast message in the second layer domain. The message is encapsulated and sent to compute2; 3) The compute2 virtual switch receives the message, decapsulates the message, and sends the message to the multicast forwarding device; 4) The multicast forwarding device virtual interface 1 receives the message, detects the multicast source address and the multicast destination address, and performs NAT conversion on the message according to the rules. The message is converted into the address of the virtual interface 2, and the message is encapsulated by GRE. The remote IP of the encapsulation is the IP address of the core switch; 5) The platform internal switch forwards the message to the core switch; 6) The core switch receives the message, decapsulates the message, adds the message to the multicast group, and forwards the message to the multicast receiver.

4. The method of claim 1, wherein The VPC network type is a VLAN mode, but the switch of the VLAN network where the VPC is located supports multicast function processing flow: In this case, the multicast forwarding device is not needed. When the virtual machine in the VPC sends a message, the message is sent to the physical switch through the VLAN network. The switch supports multicast forwarding function, and the message is registered in the multicast table, so that the multicast message can be forwarded to the multicast receiver.

5. The method of claim 1, wherein The VPC network type is a VLAN mode, but the switch of the VLAN network where the VPC is located does not support multicast function processing flow: 1) The virtual machine in the VPC sends a multicast message to the physical switch as a multicast source; 2) The physical switch receives the multicast message and forwards the multicast message in the second layer domain. The message is sent to the compute2 multicast forwarding device; 3) The multicast forwarding device virtual interface 1 receives the message, detects the multicast source address and the multicast destination address, and performs NAT conversion on the message according to the rules. The message is converted into the address of the virtual interface 2, and the message is encapsulated by GRE. The remote IP of the encapsulation is the IP address of the core switch; 4) The platform internal switch forwards the message to the core switch; 5) The core switch receives the message, decapsulates the message, adds the message to the multicast group, and forwards the message to the multicast receiver.

6. A system for executing the method of any one of claims 1-5, comprising the following components: 1) a northbound interface; 2) a configuration database; 3) a platform management component; and 4) a multicast forwarding device. 1) The northbound interface provides a series of RESTFUL interfaces for creating, deleting, and viewing the multicast forwarding device for the cloud computing management platform or third-party platform; 2) The configuration database is used to record the relevant information created by the user; 3) The platform management component is used to create multicast forwarding device resources; 4) The multicast forwarding device filters the multicast source message, forwards the legal multicast message, and performs NAT conversion and forwarding on the multicast message according to the configured network type. ​ ​

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