WO2008031342A1

WO2008031342A1 - A method, system and layer 2 equipment for implementing the fast convergence of multicast forwarding path in layer 2

Info

Publication number: WO2008031342A1
Application number: PCT/CN2007/070274
Authority: WO
Inventors: Haizhou Xiang; Yang Yang
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-09-07
Filing date: 2007-07-11
Publication date: 2008-03-20
Also published as: CN101141383A

Abstract

A method, system and layer 2 equipment for implementing the fast convergence of multicast forwarding path in layer 2 are provided. The method includes: when multicast link of layer 2 changes, layer 2 equipment is preestablished to send query information; when the layer 2 equipment, which has received report information fed back by host, confirms that the multicast group in which the host present has changed, it updates the multicast forwarding path in layer 2. The system includes: router and a plurality of layer 2 equipments, said a plurality of layer 2 equipments including a preestablished layer 2 equipment. Said preestablished layer 2 equipment includes: link sensitivity unit, adapted to sense the change of multicast link in layer 2, outputs trigger information when it senses that the multicast link in layer 2 has changed; message transmission unit, sends query information based on the trigger information outputted by link sensitivity unit; said preestablished layer 2 equipment receives the report message fed back by the host, and it triggers the update unit when it has ensured that the multicast group in which the host present has changed based on said report message, and said update unit updates the multicast forwarding path in layer 2.

Description

Method, system and layer 2 device for realizing fast convergence of layer 2 multicast forwarding path

[1] Technical field

[2] The present invention relates to the field of multicast technologies, and in particular, to a fast convergence method, system, and Layer 2 device for a Layer 2 multicast forwarding path.

[3] Background of the invention

[4] Multicast technology is a technology that sends information from one node to multiple receivers. Multicast technology is implemented.

IP

Efficient data transfer from point to point in the network can save a lot of network bandwidth and reduce network load. More importantly, some new value-added services can be easily provided by utilizing the multicast characteristics of the network, for example, online live broadcasting in the field of Internet information services, Internet TV, distance education, telemedicine, Internet radio, real video conferencing, and the like.

[5] Currently, IGMP (Internet Group Management Protocol) protocol and IGMP Snooping are used.

(Internet Group Management Listening Protocol) In the Layer 2 multicast network of the protocol, the router periodically sends IGMP Query (IGMP).

A general-purpose query packet is used to obtain information about a host joining or leaving a multicast group. The switch that implements the Layer 2 multicast function can listen to IGMP packets to establish a Layer 2 multicast forwarding path.

[6] Currently, the convergence process of the multicast forwarding path of the Layer 2 multicast network is as follows: When the Layer 2 link changes, the STP, the Fast Ring Protection Protocol RRPP, or the Resilient Packet Ring RPR may be used. Layer link status changes, including other Layer 2 link changes. The original multicast forwarding link will be broken, but the multicast stream will not be automatically forwarded from another backup link. The router resends IGMP Query (IGMP General Query Message) and the host sends an IGMP report (IGMP)

The report message is sent in response to the query of the router. After the Layer 2 switch updates the multicast forwarding path by re-learning the IGMP report packet of the host, the multicast stream is forwarded according to the updated multicast forwarding path.

[7] In the process of implementing the present invention, the inventor found that the convergence process of the forwarding path of the above-mentioned Layer 2 multicast network has at least the following problems: [8] Since the router is scheduled to send IGMP

Query packets (the interval is usually more than 1 minute). Therefore, during the next time the link is disconnected from the router, the multicast service cannot be switched to the backup link. The multicast stream will remain unreachable. In this way, the Layer 2 multicast forwarding path cannot be quickly convened after the Layer 2 link changes, thereby reducing the reliability of the multicast service.

[9] Summary of the invention

[10] The embodiment of the present invention provides a fast convergence method, a system, and a Layer 2 device of a Layer 2 multicast forwarding path. After the Layer 2 device is configured to change on the Layer 2 multicast link, the router immediately sends the switch instead of the router. Query information to query the change of the multicast group where the host resides. The convergence speed of the Layer 2 multicast forwarding path is improved.

[11] A method for implementing fast convergence of a Layer 2 multicast forwarding path according to an embodiment of the present invention includes: [12] When a Layer 2 multicast link changes, a Layer 2 device is configured to send query information. Query the changes of the multicast group where the host resides.

[13] The Layer 2 device in the Layer 2 network that receives the report information returned by the host updates the Layer 2 multicast forwarding path after determining that the host is in the multicast group.

[14] The embodiment of the present invention further provides a system for implementing fast convergence of a Layer 2 multicast forwarding path, including: a router and multiple Layer 2 devices, where the multiple Layer 2 devices include at least one preset Layer 2 device. The preset Layer 2 device includes:

[15] The link sensing unit is configured to sense a change of the Layer 2 multicast link, and output a trigger information when it senses that the Layer 2 multicast link changes.

[16] The message sending unit is configured to send the query information according to the trigger information output by the link sensing unit, to query the change of the multicast group where the host is located;

[17] The pre-configured Layer 2 device receives the report message returned by the host, and after determining that the multicast group of the host changes according to the report message, triggering an update unit, where the update unit pairs the second layer group The broadcast forwarding path is updated.

[18] The embodiment of the present invention further provides a layer 2 device, where the layer 2 device includes:

[19] The link sensing unit is configured to sense a change of the Layer 2 multicast link, and output a trigger information when it detects that the Layer 2 multicast link changes. [20] The message sending unit is configured to send the query information according to the trigger information output by the link sensing unit, to query the change of the multicast group where the host is located;

[21] The layer 2 device receives the report message that is sent back by the host, and after determining that the multicast group of the host changes according to the report message, triggering an update unit, where the update unit pairs the layer 2 multicast forwarding path Update.

[22] According to the technical solution provided by the foregoing embodiment of the present invention, the Layer 2 device in the Layer 2 multicast network is configured, and after the Layer 2 link changes, the Layer 2 device can replace the router and the device. Respond to the change of the Layer 2 link, so that the multicast stream can be forwarded according to the new link. Therefore, the embodiment of the present invention can implement the fast convergence of the Layer 2 multicast forwarding path after the change of the Layer 2 link, thereby ensuring the reliability of the multicast service.

[23] BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an implementation process of a method according to an embodiment of the present invention; FIG.

2a to 2d are schematic diagrams showing a specific implementation process of an embodiment of the present invention.

[26] Mode for carrying out the invention

In the embodiment of the present invention, the Layer 2 device can be configured to respond to the change of the Layer 2 link to implement fast convergence of the Layer 2 multicast forwarding path, thereby overcoming the problems in the prior art.

[28] The method for fast convergence of the Layer 2 multicast forwarding path will be described in detail below with reference to FIG. 1 and FIG. 2a to FIG. 2d.

The method of the embodiment of the present invention specifically includes: when a Layer 2 multicast link changes, the Layer 2 device that is closest to the router sends the query information, and the change of the multicast group where the host is located; The Layer 2 device that receives the report information returned by the host updates the Layer 2 multicast forwarding path according to the report information after determining that the multicast group of the host changes. The query information is usually an Internet Group Management Protocol (IGMP) general query message, and the report information is usually an IGMP report message.

As shown in FIG. 1 , the method according to the embodiment of the present invention specifically includes the following steps:

[31] Step 10: Configure the Layer 2 device closest to the router in the Layer 2 network.

[32] Step 11. After the Layer 2 device that is closest to the router detects the change of the Layer 2 link, it sends an IGMP Query message to the host.

[33] Step 12: The host replies to the IGMP Report message according to the received IGMP Query message. [34] Step 13, the Layer 2 device that receives the IGMP Report message in the Layer 2 network, and updates the Layer 2 multicast forwarding table according to the IGMP report message.

[35] Step 14. The multicast stream is forwarded according to the link in the updated Layer 2 multicast forwarding table.

[36] The following is a Layer 2 network as shown in Figure 2a to Figure 2d. The Layer 2 switch LSW closest to the router is used.

1 Configuring to allow LSW1 to respond to changes in the Layer 2 link to further illustrate the specific implementation process of the method according to the embodiment of the present invention.

[37] As shown in Figure 2a, Layer 2 devices in the network include: Layer 2 switch LSW1, Layer 2 switch LSW2, Layer 2 switch LSW3, and Layer 2 switch LSW4. LSW1 is directly connected to the router and is the second layer closest to the router. device. User 1 exchanges information between the multicast forwarding path formed by LSW1, LSW2, and LSW4 and the router. User 2 exchanges information between the multicast forwarding path formed by LSW1 and LSW3 and the router.

[38] In the above Layer 2 network, IGMP is enabled on the router, and IGMP is enabled on LSW1, LSW2, LSW3, and L SW4 respectively.

Snooping function, and enable MSTP (multiple spanning tree protocol, through selective blocking of network redundant links, pruning the network into a tree to achieve the purpose of eliminating loops, and having link backup function), making LSW3 and The link between LSW4 is blocked to prevent loops.

[39] As shown in Figure 2b, assuming that the link between LSW2 and LSW4 is broken, the multicast stream can no longer be forwarded from LSW2 to LSW4. Therefore, the link between LSW3 and LSW4 will be blocked, but because the router is scheduled to send IGMP.

Query packet query for the change of the multicast group where the host resides (the interval is usually more than one minute). Therefore, the next time the link is broken, the router sends IGMP.

During the Query message, User 1 naturally cannot send IGMP.

Report message to report the changes of the multicast group in which it is located, and LSW3 does not learn the IGMP sent by user 1.

In the Report message, the multicast stream will not be sent from LSW3 to LSW4. In this way, the multicast stream will remain unreachable during the period when the link is disconnected from the router and the IGMP Query message is sent.

[40] As shown in Figure 2c, in order to allow the multicast forwarding path to be updated quickly, it is not necessary to wait for the router to send IGMP.

The Query message is updated, and the LSW1 closest to the router can be changed on the cognitive link. Send the IGMP general query message to the router immediately (the source IP address can be set to non-zero) to query the change of the multicast group where the host is located. When user 1 receives the IGMP general query message, it will send the IGMP report immediately. The packet responds to the query and reports the change of the multicast group. The LSW3 and LSW1 learn the IGMP report message of the user 1 and update the Layer 2 multicast forwarding table according to the IGMP report message of the user 1. Related entries: The multicast stream is forwarded according to the new link according to the updated Layer 2 multicast forwarding entry.

[41] For user 2, after receiving the IGMP general query message, user 2 will immediately send an IGMP report message to respond to the query and report the changes of the multicast group in which it is located. Then LSW3 and LSW1 will also be reported. The user 2 reports the packet, but the multicast group does not change. Therefore, the multicast stream is still forwarded according to the original link.

[42] As shown in Figure 2d, the multicast stream reaches user 1, P along the new multicast forwarding path. After the Layer 2 link changes, User 1 passes the multicast forwarding path consisting of LSW1, LSW3, and LSW4. Interact with the router

Ι π Λ∑! ,.

[43] The embodiment of the present invention further provides a system for implementing fast convergence of a Layer 2 multicast forwarding path, including: a router and multiple Layer 2 devices, where the Layer 2 device includes a preset Layer 2 device, and the The configuration of the Layer 2 device includes: a link sensing unit, a message sending unit, and an update unit. The other Layer 2 devices of the non-preconfigured Layer 2 device are provided with an update unit. The following is a combination of FIG. 2a, FIG. 2b, and FIG. The system of the embodiment of the invention will be described in detail.

[44] First, the link sensing unit will be described in detail in conjunction with Figs. 2a and 2b.

[45] The link sensing unit is configured to sense a change of the Layer 2 link, and when it detects that the Layer 2 link changes, outputting trigger information to trigger the message sending unit;

As shown in Figure 2a, the Layer 2 device in the network includes: Layer 2 switch LSW1, Layer 2 switch LSW2, Layer 2 switch LSW3, and Layer 2 switch LSW4. The Layer 2 device forms a ring network. LSW1 is a pre-configured Layer 2 device, that is, the Layer 2 switch LSW1 closest to the router is configured to allow LSW1 to respond to the change of the Layer 2 link. User 1 interacts with the router through the multicast forwarding path formed by LSW1, LSW2, and LSW4. Information, the interaction between the multicast forwarding path formed by user 2 through LSW1 and LSW3 and the router is as shown in Figure 2b. When the Layer 2 link changes, that is, the link between LSW2 and LSW4 is disconnected. The link sensing unit of LSW1 senses the change of the Layer 2 link and triggers the message sending unit.

[48] The message transmitting unit and the updating unit will be described in detail in conjunction with Figs. 2b and 2c.

[49] The message sending unit is configured to: when the layer 2 link changes, that is, after receiving the trigger information output by the link sensing unit, send the query information, and query the change of the multicast group where the host is located;

[50] The Layer 2 device that receives the report message returned by the host changes the multicast group where the host is located.

And triggering an update unit, where the update unit updates the layer 2 multicast forwarding path in the layer 2 device.

[51] As shown in Figure 2b, when the link between LSW2 and LSW4 is broken, the multicast stream can no longer be forwarded from LSW2 to LSW4. At this point, the link between LSW3 and LSW4 will be opened, but since the router is scheduled to send IGMP

The Query message is used to query the change of the multicast group where the host is located (the interval is usually more than one minute). Therefore, during the next time the link is disconnected from the router, the user 1 cannot send an IGMP Report message to report it. The change of the multicast group is located, and LSW3 does not learn the IGMP sent by user 1.

After the Report message, the multicast stream will not be sent from LSW3 to LSW4. In this way, the multicast stream will remain unreachable during this period.

[52] As shown in Figure 2c, in order to allow the multicast forwarding path to be updated quickly, the link sensing unit of the Layer 2 device will change after the sensing link changes after the router does not need to send the IGMP general query message. The trigger message sending unit sends the IGMP general query message (the source IP address can be set to non-zero) to query the change of the multicast group where the host is located. When user 1 receives the IGMP general query. After the message, it will reply to the IGMP report message immediately to respond to the query and report the changes of the multicast group it is in. After receiving the report message of user 1, LSW3 and LSW1 trigger the message update unit to update the Layer 2 multicast forwarding path.

[53] The embodiment of the present invention further provides a Layer 2 device that implements a fast convergence of a Layer 2 multicast forwarding path, where the Layer 2 device includes: a link sensing unit, a message sending unit, and an updating unit.

[54] The link sensing unit is configured to sense a change of the Layer 2 link, and when it detects that the Layer 2 link changes, outputting trigger information to trigger the packet transceiver unit;

[55] The message sending unit is configured to receive the touch of the link sensing unit when the layer 2 link changes. After sending a message, send a query to query the changes of the multicast group where the host resides.

[56] The layer 2 device that receives the report message sent back by the host, after determining that the multicast group of the host is changed, triggers an update unit, and the update unit updates the layer 2 multicast forwarding path.

[57] The specific application process of the above three units in the embodiment of the present invention has been described in detail in the above system for implementing fast convergence of the Layer 2 multicast forwarding path, and is not described herein.

In summary, the embodiment of the present invention implements Layer 2 multicast forwarding fast convergence by configuring a Layer 2 device (generally a Layer 2 device closest to the router) to ensure fast convergence of Layer 2 multicast forwarding, thereby ensuring multicast. Business reliability. Layer 2 link changes described in the embodiments of the present invention include various types of Layer 2 link changes, such as MSTP (Multiple Spanning Tree Protocol)-based Layer 2 link change, and RPR (Resilient Packet Ring)-based Layer 2 Link change, Layer 2 link change based on RRPP (Fast Ring Protection Protocol), etc.

[59] Here, the embodiment of the present invention is only a Layer 2 multicast network that uses the IGMP protocol, and the query information is usually an Internet Group Management Protocol (IGMP) general query message, and the report information is usually an IGMP report. The description is made by way of example, but those skilled in the art should understand that the embodiments of the present invention are not limited to the IGMP protocol. In addition, the embodiment of the present invention is a Layer 2 device that sends a query message instead of a router by a Layer 2 switch that is closest to the router, and receives the report information returned by the host. After determining that the multicast group of the host changes, the second layer is The multicast forwarding path is updated as an example. It should be understood by those skilled in the art that the embodiments of the present invention are not limited to the Layer 2 device that is closest to the router, and all Layer 2 devices that belong to the downstream of the router may implement the present invention.

The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of within the technical scope disclosed by the present invention. Changes or substitutions are intended to be included within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

[1] A method for implementing fast convergence of a Layer 2 multicast forwarding path, where the method includes:

After the Layer 2 multicast link changes, the Layer 2 device is configured to send query information to query the changes of the multicast group in the host.

The Layer 2 device that receives the report information returned by the host in the Layer 2 network updates the Layer 2 multicast forwarding path after determining that the host has changed its multicast group.

[2] The method according to claim 1, wherein the query information is an Internet Group Management Protocol (IGMP) general query message, and the report information is an IGMP report message.

[3] The method according to claim 1, wherein the pre-configured Layer 2 device is a Layer 2 device that is closest to the router in the Layer 2 network.

[4] 4. The method according to claim 3, wherein the second layer device closest to the router is a layer 2 switch closest to the router.

[5] The method according to claim 1, wherein the Layer 2 multicast link includes a multi-spanning tree protocol MSTP, or an elastic packet ring RPR, or a fast ring network protection protocol RRPP. Layer multicast link.

[6] 6. A system for implementing fast convergence of a Layer 2 multicast forwarding path, comprising: a router and multiple Layer 2 devices, where the multiple Layer 2 devices include at least one preset Layer 2 device, wherein The preset Layer 2 device includes:

The link sensing unit is configured to sense a change of the Layer 2 multicast link, and output a trigger information when it detects that the Layer 2 multicast link changes.

The message sending unit is configured to send the query information according to the trigger information output by the link sensing unit, to query the change of the multicast group where the host is located;

The pre-configured Layer 2 device receives the report message that is sent back by the host, and after determining that the multicast group of the host changes according to the report message, triggers an update unit, where the update unit pairs the Layer 2 multicast forwarding path. Update.

[7] 7. The system according to claim 6, wherein the pre-configured Layer 2 device is a Layer 2 device that is closest to the router in the Layer 2 network.

[8] 8. The system according to claim 6, wherein the Layer 2 multicast link includes a multi-spanning tree protocol MSTP, or an elastic packet ring RPR, or a fast ring network protection protocol RRPP. Layer multicast link.

[9] 9. A Layer 2 device, where the Layer 2 device includes:

The Layer 2 device receives the report message that is sent back by the host, and after determining that the multicast group of the host changes according to the report message, triggers an update unit, and the update unit updates the Layer 2 multicast forwarding path.