WO2012103748A1

WO2012103748A1 - Multicast control method, routing device and multicast system

Info

Publication number: WO2012103748A1
Application number: PCT/CN2011/079003
Authority: WO
Inventors: 范树学; 陈重; 赵大赫; 徐旭
Original assignee: 华为技术有限公司
Priority date: 2011-02-01
Filing date: 2011-08-26
Publication date: 2012-08-09
Also published as: CN102624604A; CN102624604B

Abstract

Disclosed are a multicast control method, a routing device and a multicast system. The method comprises: a second routing device in a sharing network segment receiving a first join request periodically sent by a first routing device in the sharing network segment, the request carrying information of an RPF upstream neighbor of the first routing device; when determining that the second routing device itself is not an RPF upstream neighbor of the first routing device but a downstream routing device in the sharing network segment, the second routing device, after receiving a second join request sent by a downstream receiving device, temporarily not forwarding the second join request to an RPF upstream neighbor that receives the second join request and is acquired according to unicast routing; and when again receiving the first join request or receiving a leave request sent by the first routing device, setting the RPF upstream neighbor that receives the second join request and is acquired by the second routing device itself according to the unicast routing to an RPF upstream neighbor carried in the first join request, and sending the second join request to the RPF upstream neighbor.

Description

The present invention claims to be submitted to the Chinese Patent Office on February 1, 2011, and the application number is 201110034461.7, and the invention name is "a multicast control method, a routing device, and a multicast system." The priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference. TECHNICAL FIELD The present invention relates to the field of network communication technologies, and in particular, to a multicast control method, a routing device, and a multicast system. BACKGROUND OF THE INVENTION With the rapid development of the Internet, IP (Internet Protocol) protocols have enabled efficient data transmission from point to point in IP networks. Because multicast technology can effectively save bandwidth to control network traffic, reduce server load and reduce network load, it has a wide range of applications in real-time data transmission, multimedia conferencing and many other aspects.

The IP multicast protocol includes a protocol between the router and the receiver and a protocol between the router and the router, and the combination is used to construct a multicast forwarding tree from the multicast source to the multicast data receiver. The protocol between the router and the receiver host is usually IGMP (Internet Group Management Protocol). The protocol independent multicast (PIM) protocol is usually used between the router and the router. The Protocol Independent Multicast-Sparse Mode (PIM-SM) protocol is widely used as a typical multicast routing standard.

In the PIM-SM protocol, the process of establishing a multicast forwarding tree is as shown in FIG. 1 , where 101 to 105 are five routers, 106 is a first receiving device, 107 is a second receiving device, and 108 is a multicast source. After receiving the IGMP join request from the first receiving device 106, the router 104 calculates the route to the multicast source 108 according to the unicast, and sends the PIM join message to the upstream router hop by hop, and routes the device 104-> Routing device 102->Routing device 101 establishes a multicast join tree, and then the multicast source along the PIM The reverse direction of the message is forwarded from the routing device 101 -> routing device 102 -> routing device 104 to the first receiving device 106.

According to the principle that the PIM establishes a forwarding tree, the direction in which the PIM sends the join message to the upstream is calculated according to the unicast route. Then, if the routing device 105 receives the same as the first receiving device 106 from the second receiving device 107. The IGMP join request calculates the route from the routing device 105 to the multicast source 108 through the routing device 103 based on the unicast route, and thus establishes a multicast forwarding tree from the routing device 101->the routing device 103->the routing device 105. At this time, it can be found that the routing device 102 and the routing device 103 simultaneously forward the same multicast data stream to the shared network segment. According to the IP multicast protocol, Assert competition occurs when duplicate multicast data is generated in the shared network segment, as shown in Figure 2.

In order to avoid the generation of duplicate multicast data on the shared network segment, one of the prior art solutions is to select a router with low overhead to continue to forward the multicast data stream according to the cost of each router to the multicast source. The routers with large overheads stop forwarding multicast data streams, and the routers with low overheads periodically broadcast Assert packets carrying their own overhead information on the shared network segment to avoid re-generation of duplicate multicast data, thus eliminating the shared network segment. Double traffic on. It can be seen in the process that the AsSert competition is performed after repeated multicast data has appeared on the shared network segment, and during the Assert competition, the data received by the user through the shared network segment will have an impact. For example, a large number of mosaics appear in the received video image, and the user experience is poor. At the same time, the Assert message is sent periodically, which also increases the network load.

The second solution in the prior art is to start sending Assert messages periodically before repeated multicast data has appeared on the shared network segment. Although the scheme can avoid the generation of double traffic in advance, in the shared network segment where no duplicate multicast data is generated, periodically sending useless Assert packets will affect performance and increase network load. SUMMARY OF THE INVENTION In view of this, an embodiment of the present invention provides a multicast control method, a routing device, and a multicast system, so as to avoid repeated multicast data on a shared network segment.

The embodiment of the invention provides a multicast control method, and the method includes:

The second routing device on the shared network segment receives the first joining request periodically sent by the first routing device on the shared network segment, where the first joining request carries the reverse path of the first routing device. The path forwards the RPF upstream neighbor information and the address information of the multicast source.

The second routing device determines that the RPF upstream neighbor is not the first routing device according to the RPF upstream neighbor information, and determines that it is the downstream routing device in the shared network segment according to the address information of the multicast source. After receiving the second join request sent by the downstream receiving device, the second join request is not forwarded to the RPF upstream neighbor that is obtained according to the unicast route and receives the second join request.

When the second routing device receives the first joining request again or receives the leaving request sent by the first routing device, the RPF upstream neighbor that receives the second joining request according to the unicast route The RPF upstream neighbor that is carried in the first join request is sent, and the second join request is sent to the RPF upstream neighbor that is carried in the first join request.

A routing device, the routing device is located on a shared network segment, and the router includes: a receiving module, configured to receive a first joining request periodically sent by a first routing device on the shared network segment, where the first The RSP carries the reverse path of the first routing device to forward the RPF upstream neighbor information and the address information of the multicast source.

a device identification module, configured to determine, according to the RPF upstream neighbor information, whether it is an RPF upstream neighbor of the first routing device, and determine, according to the address information of the multicast source, whether it is a downstream in the shared network segment. Routing device

a request processing module, configured to: when determining that it is a downstream routing device in the shared network segment, and receiving a second joining request sent by the downstream receiving device, temporarily not forwarding the second joining request to the unicast routing Obtaining an RPF upstream neighbor that receives the second join request, and when the receiving module receives the first join request or receives the leave request sent by the first routing device, obtain the self according to the unicast route. The RPF upstream neighbor that receives the second join request is set to be the RPF upstream neighbor carried in the first join request, and sends the second join request to the RPF upstream neighbor carried in the first join request.

A multicast system, the system includes: at least one first routing device that is located on a shared network segment, and at least one second routing device that is located on the shared network segment, where

The first routing device is configured to periodically send a first join request to the second routing device, where the first join request carries a reverse path of the first routing device to forward the RPF upstream neighbor information, and Address information of the multicast source; The second routing device is configured to receive the first join request, and determine that the RPF upstream neighbor is not the first routing device according to the RPF upstream neighbor information, and determine according to the address information of the multicast source. When the second routing request sent by the downstream receiving device is received, the second joining request is not forwarded to the receiving second according to the unicast route. Adding the requested RPF upstream neighbor; when the second routing device receives the first joining request again or receives the leaving request sent by the first routing device, receiving the self-receiving according to the unicast route The second RPF upstream neighbor is configured to be the RPF upstream neighbor that is carried in the first join request, and sends the second join request to the RPF upstream neighbor that is carried in the first join request.

Compared with the prior art, the downstream routing device on the shared network segment in the embodiment of the present invention does not directly forward the join request to the upstream routing device obtained by the unicast path after receiving the join request sent by the downstream receiving device. The upstream routing device that is consistent with the other joining requests that exist in the shared network segment is forwarded, and the access request is forwarded to the same upstream routing device, so as to avoid multiple different multicast data for the same multicast data in the shared network segment. Multicast data transmission path. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description are only the present drawings. Some embodiments of the invention may also be used to obtain other figures from these figures without departing from the art.

Figure 1 is a schematic diagram of a process of establishing a multicast forwarding tree in the PIM-SM protocol;

2 is a schematic diagram of a traffic conflict when a duplicate multicast data is generated in a shared network segment; FIG. 3 is a schematic flowchart of a multicast control method according to an embodiment of the present invention;

4 is a schematic structural diagram of a topology of a multicast network according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a routing device on a shared network segment according to an embodiment of the present invention. The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, instead of All embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without departing from the inventive scope are the scope of the present invention.

In order to avoid the defect of the same multicast data transmission on the shared network segment, the embodiment of the present invention provides a multicast control method, a routing device, and a multicast system.

The embodiment of the invention provides a multicast control method. As shown in FIG. 3, the method may include:

301. The second routing device on the shared network segment receives the first join request periodically forwarded by the first routing device on the shared network segment, where the first join request carries the RPF of the first routing device. (Reverse-path forwarding, reverse path forwarding) upstream neighbor information, and address information of the multicast source;

In the PIM-SM protocol, when a routing device on a shared network segment of the multicast tree needs to join the source group of the multicast tree according to the request of the receiver, it is first based on its own routing entry. The source address information is used to query the unicast route between the routing device and the routing device where the source address is located in the routing entry, and then determine the upstream RPF upstream neighbor according to the unicast route that is queried, and The RPF upstream neighbor periodically sends a join request, and the join request carries the information about the RPF upstream neighbor determined by the RPF, and the source and group address of the multicast tree. According to the PIM-SM protocol, the destination address corresponding to the join request is all the routing devices loaded with PIM-SM in the network segment. Therefore, although the join request is sent for an upstream routing device on the shared network segment, all other routing devices on the network segment except the specific upstream routing device that load the PIM-SM protocol are also Can receive the join request. The other routing device includes not only other upstream routing devices, but also all downstream routing devices in the shared network segment except the routing device that sends the join request.

After receiving the join request sent by other routing devices on the same shared network segment, all the routing devices that have received the above-mentioned join request on the shared network segment, in order to confirm whether they need to respond to the join request, first whether they are the above-mentioned shared network. The upstream device or the downstream device in the segment is identified to perform different operations.

In the embodiment of the present invention, the join request initiated by a receiver is assumed to be the first join request, and the routing device that sends the first join request is set as the first routing device, and the routing device that receives the first join request on the shared network segment is set. For the second routing device. The second routing device determines, according to the RPF upstream neighbor information, that the RPF is not the upstream neighbor of the first routing device, and determines that it is the downstream of the shared network segment according to the address information of the multicast source. After the device is routed, after receiving the second join request sent by the downstream receiving device, the second join request is not forwarded to the RPF upstream neighbor that is obtained according to the unicast route and receives the second join request.

In the above process, after receiving the first join request, the second routing device may obtain the RPF upstream neighbor information of the first routing device carried in the first join request, so as to determine whether the first join message is sent to itself. of. When the RPF upstream neighbor information of the first routing device that is carried in the first join request does not match the self-information, the first join message is not sent to the user, and the second routing device may directly The packet carrying the first join request is discarded.

The second routing device in the shared network segment has not received the join request initiated by the downstream receiving device, but it can receive the multicast data forwarded to the first routing device in the shared network segment, thereby creating a corresponding entry. . Since the second routing device does not receive the join request initiated by the downstream receiving device, the entry cannot guide the forwarding of the received multicast data, and the corresponding multicast data is terminated on the second routing device.

When receiving the second join request sent by the downstream receiving device, the second routing device finds that the data active entry exists, and adds the corresponding outgoing interface to forward the multicast data, but the second routing device does not immediately forward the second The request message is added to the RPF upstream neighbor that is obtained by the unicast route and receives the second join request, but waits for a period of time and then forwards. For example, the waiting time may be the period of the second join request.

303. When the second routing device receives the first join request or receives the leave request sent by the first routing device, the RPF upstream neighbor that receives the second join request obtained according to the unicast route The RPF upstream neighbor that is carried in the first join request is sent, and the second join request is sent to the RPF upstream neighbor that is carried in the first join request.

When the second routing device receives the first joining request sent by the first routing device, or the leaving request sent by the first routing device, obtains the RPF upstream neighbor information carried in the corresponding packet, and sets the self-acquisition obtained according to the unicast route. Receiving the RPF upstream neighbor information of the second join request, which is consistent with the RPF upstream neighbor information carried in the first join request or the leave request message sent by the first routing device, and sends the second neighbor to the RPF upstream neighbor. Join the request to avoid the out of the shared network segment There are a number of different multicast data transmission paths for the same multicast data.

It can be seen that, in the embodiment of the present invention, after receiving the join request sent by the downstream receiving device, the downstream routing device on the shared network segment does not immediately forward the join request to the upstream routing device calculated by the unicast path, but keeps the join request. An upstream routing device that is consistent with other join requests that are already in the shared network segment forwards the access request to the same upstream routing device, thereby preventing multiple different multicast data transmissions for the same multicast data in the shared network segment. path.

In addition, for example, if the second routing device has other existing routing entries, the information is retained to maintain an upstream routing device that is consistent with other joining requests already existing in the shared network segment.

When the second routing device determines that it is the upstream routing device in the shared network segment according to the address information of the multicast source, and determines whether it is the RPF upstream neighbor carried in the first joining request, if And sending, according to the address information of the multicast source, the first join request to the upper-level network segment of the shared network segment; if not, discarding the first join request.

In order to facilitate a full understanding of the technical solutions of the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described.

FIG. 4 is a schematic diagram of a topology structure of a multicast network according to an embodiment of the present invention. The routing device 102, the routing device 103, the routing device 104, and the routing device 105 are directly connected to the same shared network segment, and the routing device 102 and the routing device 103 are upstream routing devices on the shared network segment, and the routing device 104 and the routing device 105 are The shared network segment is a downstream routing device, and the routing device 102 and the routing device 103 have a common upstream routing device 101. The routing device 101 directly connects to the multicast source 108. In addition, the first receiving device 106 and the second receiving device 107 are respectively configured as routes. The device 104 and the downstream receiving device of the routing device 105. Generally, the first receiving device 106 and the second receiving device 107 are host devices that request to receive the multicast source 108 to send a data packet. For the downstream routing device 104, if it receives the join request (Joinl(S, G)) sent by the first receiving device 106, and queries the RPF upstream neighbor as the routing device 102, it sends a join request to the routing device 102. (Joinl (S, G)). At this time, all other routing devices on the shared network segment, that is, the routing device 103 and the routing device 105, will receive the join request (Joinl(S, G)). The routing device 103 and the routing device 105 respectively identify whether the upstream routing device or the downstream routing device on the shared network segment and whether it is a join request according to the join request (Join(S, G)) (Joinl(S, G) The RPF upstream neighbor specified in ). For routing device 105, assume that it is in the first receiving device When the standby 106 sends a join request (Joinl(S, G)) to the routing device 104, the second receiving device 107 does not send a join request (Join2(S, G)) to the routing device 105 to join the same source group, and therefore, the route The device 105 does not join the source group that the first receiving device 106 sends the join request to establish, and does not include the routing entry, and directly discards the join message. When the second receiving device 107 sends a join request (Join2(S, G)) to the routing device 105, the routing device 105 detects that the multicast data (Joinl(S, G)) request already exists on the shared network segment (S , G), so it does not immediately send (Join2(S, G)) to the upstream neighbor calculated according to the unicast route, but delays the sending (Join2(S, G)) message and shares the shared network segment (Joinl (S, G)) The requested multicast data, waiting for the next cycle join message sent by the routing device 104, and obtaining the information of the RPF upstream routing device 102 from the corresponding join request (Joinl(S, G)), And correcting the RPF upstream neighbor obtained by the unicast route as the routing device 102, and sending the join request (Join2(S, G)) to the routing device 102.

For the routing device 102 and the routing device 103, if it is identified as an upstream routing device on the shared network segment according to the join request (Joinl(S, G)), it continues to determine whether it is a join request (Joinl(S, G) The RPF upstream neighbor carried in the ), if yes, continues to send a join request (Joinl(S, G)) to the upper-level network segment of the shared network segment according to the address information of the multicast source; , then discard the join request (Joinl(S, G)). In the embodiment shown in FIG. 4, the routing device 102 is the RPF upstream neighbor determined in the join request (Join1 (S, G)), and the routing device 102 continues to the upper network segment of the shared network segment, that is, the routing device 101. Sending a join request (Joinl(S, G)), and the routing device 103 is not joining the RPF upstream neighbor determined in the request (Joinl(S, G)), the routing device 103 will receive the join request (Joinl(S, G) ))throw away.

In addition, the join request sent by the receiving device may be a (S, G) type join request of the specified multicast source S, or a (*, G) type join request indicating all multicast sources of the specified multicast group G. When the join request is a (S, G) join request, the downstream device on the shared network segment determines the RPF upstream neighbor by finding the unicast route to the multicast source S; for the (*, G) type join request, it finds The route of the RP (Rendezvous Point) is used to determine the RPF upstream neighbor.

In the whole implementation process of the foregoing embodiment, the routing device 105 shares the data forwarded by the multicast forwarding tree created by the routing device 104 before sending the PIM join message of the local device, and listens to the shared network segment in a sending period. After the request packet of the routing device of the multicast forwarding tree is added to the existing multicast forwarding tree, you can avoid creating different multicast forwardings on the shared network segment. The situation of double traffic is caused by the tree, and the occurrence of Assert can also be avoided.

Corresponding to the foregoing embodiment of the multicast control method, the embodiment of the present invention further provides a routing device on a shared network segment, as shown in FIG. 5, which is a schematic structural diagram of the routing device.

The receiving module 501 is configured to receive a first join request that is periodically sent by the first routing device on the shared network segment, where the first join request carries the reverse path of the first routing device to forward the RPF upstream neighbor Information, and address information of the multicast source;

The device identification module 502 is configured to determine, according to the RPF upstream neighbor information, whether it is an RPF upstream neighbor of the first routing device, and determine, according to the address information of the multicast source, whether it is in the shared network segment. Downstream routing device;

The request processing module 503 is configured to: when determining that the user is the downstream routing device in the shared network segment, and receiving the second joining request sent by the downstream receiving device, temporarily not forwarding the second joining request to the unicast according to the unicast Obtaining, by the route, the RPF upstream neighbor that receives the second join request, when the receiving module receives the first join request again or receives the leave request sent by the first routing device, obtains the self-unicast route according to the unicast route. The RPF upstream neighbor that receives the second join request is set as the RPF upstream neighbor that is carried in the first join request, and sends the second join request to the RPF upstream neighbor that is carried in the first join request.

For example, the request processing module 503 is further configured to determine, if it is the upstream routing device in the shared network segment, whether it is the RPF upstream neighbor carried in the first join request, and if yes, And sending, according to the address information of the multicast source, the first join request to the upper-level network segment of the shared network segment; if not, discarding the first join request.

For example, the first join request includes: (S, G) join request of the specified multicast source S forwarded by the first routing device, or all multicast sources of the specified multicast group G (*, G ) Join the request.

For the specific working process involved in the foregoing functional modules, reference may be made to the related content involved in the foregoing multicast control method embodiment, and no further reference is made herein.

After the routing device is located on the shared network segment, after receiving the join request sent by the downstream receiving device, the upstream routing device obtained by the unicast path calculation does not directly forward the join request, but remains in the shared network segment. An existing upstream routing device with the same join request, the access request It is forwarded to the same upstream routing device, so that multiple different multicast data transmission paths for the same multicast data can be avoided in the shared network segment.

According to the foregoing embodiment, the embodiment of the present invention further provides a multicast system, where the system includes: at least one first routing device located on a shared network segment, and at least one second routing device located on the shared network segment. , among them,

The first routing device is configured to: forward, to the second routing device, a first join request, where the join request carries a reverse path of the first routing device to forward RPF upstream neighbor information, and a multicast source Address information;

The second routing device is configured to: receive the first join request, determine, according to the RPF upstream neighbor information, that the RPF upstream neighbor is not the first routing device, and determine, according to the address information of the multicast source, When the second routing request sent by the downstream receiving device is received, the second joining request is not forwarded to the receiving second according to the unicast route. Adding the requested RPF upstream neighbor; when the second routing device receives the first joining request again or receives the leaving request sent by the first routing device, receiving the self-receiving according to the unicast route The second RPF upstream neighbor is configured to be the RPF upstream neighbor that is carried in the first join request, and sends the second join request to the RPF upstream neighbor that is carried in the first join request.

In addition, the system may further include: a multicast source, configured to send multicast data according to the first join request of the first routing device or the second join request of the second routing device.

For example, the second routing device is further configured to: determine, according to the address information of the multicast source, that it is an upstream routing device in the shared network segment, determine whether it is the first joining request. The RPF upstream neighbor, if yes, continues to send the first join request to the upper-level network segment of the shared network segment according to the address information of the multicast source; if not, discard the first One join request.

For the system embodiment, since it basically corresponds to the method and device embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method and the device embodiment. The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, ie may be located One place, or it can be distributed to multiple network elements. Can be based on actual needs Some or all of the modules are selected to achieve the objectives of the solution of the embodiment. Those of ordinary skill in the art can understand and implement without any creative effort.

A person skilled in the art can understand that all or part of the process of implementing the above embodiment method can be completed by a computer program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, the flow of an embodiment of the methods as described above may be included. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the embodiments of the invention. . Therefore, the present embodiments of the invention are not to be limited to the embodiments shown herein, but are to be accorded to the broadest scope of the principles and novel features disclosed herein.

Claims

Rights request

A multicast control method, the method comprising:

The second routing device on the shared network segment receives the first join request periodically sent by the first routing device on the shared network segment, where the first join request carries the reverse path forwarding of the first routing device. RPF upstream neighbor information, and address information of the multicast source;

The multicast control method according to claim 1, wherein the method further comprises: determining, by the second routing device, that it is within the shared network segment according to address information of the multicast source The upstream routing device determines whether it is the upstream neighbor of the RPF carried in the first join request.

If the RPF upstream neighbor is carried in the first join request, the first join request is sent to the upper network segment of the shared network segment according to the address information of the multicast source; If the RPF upstream neighbor is not included in the first join request, the first force incoming request is discarded.

The multicast control method according to any one of claims 1 to 2, wherein the second routing device on the shared network segment receives the first forwarding device on the shared network segment. A join request, including:

The second routing device receives the (S, G) join request of the specified multicast source S forwarded by the first routing device, or the (*, G) join request of all multicast sources of the specified multicast group G.

A routing device, wherein the routing device is located on a shared network segment, and the router includes: a receiving module, configured to receive a first join request periodically sent by the first routing device on the shared network segment, where the first join request carries the reverse path of the first routing device to forward the RPF upstream neighbor information And the address information of the multicast source;

The routing device according to claim 4, wherein the request processing module is further configured to determine whether it is the first joining when determining that it is an upstream routing device in the shared network segment The RPF upstream neighbor that is carried in the request, if it is the RPF upstream neighbor carried in the first join request, continues to send to the upper-level network segment of the shared network segment according to the address information of the multicast source. The first join request is discarded; if the RPF upstream neighbor is not included in the first join request, the first join request is discarded.

The routing device according to any one of claims 4 to 5, wherein the first joining request comprises: (S, G) of the specified multicast source S forwarded by the first routing device Join the request, or indicate the (*, G) join request for all multicast sources of the specified multicast group G.

A multicast system, the system includes: at least one first routing device that is located on a shared network segment, and at least one second routing device that is located on the shared network segment, where a routing device, configured to periodically send a first join request to the second routing device, where the first join request carries a reverse path of the first routing device to forward RPF upstream neighbor information, and a multicast source Address information;

The second routing device is configured to receive the first join request, and determine, according to the RPF upstream neighbor information, that the RPF upstream neighbor is not the first routing device, and according to the multicast When the address information of the source is determined to be the downstream routing device in the shared network segment, after receiving the second joining request sent by the downstream receiving device, the second joining request is not forwarded to the unicast routing. Receiving the RPF upstream neighbor of the second joining request; when the second routing device receives the first joining request again or receives the leaving request sent by the first routing device, obtaining the self according to the unicast route The RPF upstream neighbor that receives the second join request is set to be the RPF upstream neighbor carried in the first join request, and sends the second join request to the RPF upstream neighbor carried in the first join request.

The multicast system according to claim 7, wherein the system further comprises: a multicast source, configured to be based on the first joining request of the first routing device or the second joining of the second routing device Request to send multicast data.

The multicast system according to claim 7 or 8, wherein the second routing device is further configured to determine that it is an upstream in the shared network segment according to the address information of the multicast source. The routing device determines whether it is the RPF upstream neighbor carried in the first join request, and if it is the RPF upstream neighbor carried in the first join request, according to the address information of the multicast source, continues to The first network segment of the shared network segment sends the first join request; if it is not the RPF upstream neighbor carried in the first join request, the first join request is discarded.