WO2012041104A1

WO2012041104A1 - Method, system and modem for implementing internet group management protocol snooping

Info

Publication number: WO2012041104A1
Application number: PCT/CN2011/076741
Authority: WO
Inventors: 唐剑波
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-09-27
Filing date: 2011-06-30
Publication date: 2012-04-05
Also published as: CN101964733B; CN101964733A

Abstract

The present invention discloses a method, a system and a modem for implementing Internet Group Management Protocol (IGMP) snooping. The method for implementing IGMP snooping includes: the modem receives a leave packet from a Local Area Network (LAN) device, searches a multicast table, stores the leave packet when it is retrieved that the multicast in the multicast table includes multiple entries, transmits a query packet to the LAN device, and transmits the leave packet to an upstream device on the condition that no response is received from the LAN device. With the present invention, the black screen caused by the LAN device failing to receive a certain channel can be prevented.

Description

The present invention relates to the field of communications, and in particular to a method and system for implementing Internet Group Management Protocol Snooping (IGMP Snooping). modem. BACKGROUND OF THE INVENTION At present, IGMP Snooping of a general modem (modem) is to communicate between a local area network (LAN) user and a WAN port uplink device of a wide area network (WAN). The IGMP 4 message maintains a forwarding table of the correspondence between the multicast address and each port on the LAN side. After receiving the multicast data packet, it searches the table according to the multicast address to determine which LAN ports should forward the multicast packet to. The main process of IGMPv2 messages is as follows. When receiving an IGMP report (response) from pc (computer;), stb (set top box), etc. from a LAN port, (using multicast address, LAN port, source mac), look up whether the multicast mac table is already The forwarding entry exists. If it exists, the aging time is updated. If it does not exist, the multicast forwarding address is received by the multicast address, the LAN port number of the report packet, the MAC address of the device that sends the report packet, and the aging time. Add to the multicast mac table, and forward the message to the WAN port; when receiving IGMP leave message from a LAN port (leave 4 messages), the same (by multicast address, LAN port, source) Mac) Find whether the forwarding entry exists in the multicast mac table. If it exists, delete the entry from the multicast mac table, and use the multicast address to find out whether other entries exist. If there are other LAN ports, If the IGMP leave packet is discarded, the IGMP leave packet is not forwarded to the WAN port. If there is no other entry in the multicast, the IGMP leave message is forwarded to the WAN port. After receiving the IGMP query message from the WAN port, Directly All LAN ports are forwarded; in addition, when the aging time of an entry is decremented to 0, the entry is deleted. As can be seen from the above IGMP snooping process, if there are two entries of the same multicast A in the multicast mac table, that is, when two ports on the LAN side join the same multicast group A, only When the last port leaves the multicast group, the modem can forward the IGMP Leave message to the WAN port. If the first port leaves, the modem forwards the IGMP leave message to the WAN port, causing the uplink device to stop sending the corresponding multicast A to the modem's WAN port. If the packet is received, the other port that needs the multicast cannot receive the packet from multicast A. In addition, it can be seen that the IGMP report 4 from any LAN port can be received by other LAN devices. The modem itself does not actively send IGMP query 4 messages, only the 4 bar received from the WAN port. 4 艮 text is transmitted to all LAN ports. In practical applications, the inventors have found that some set-top boxes in the related technologies have the following characteristics for multicast processing, for example: typical networking mode is shown in Figure 1, and set-top boxes A and B are added to multicast 239.1.1.1, multicast mac There are two entries a and b in the forwarding table. The uplink device periodically sends IGMP query messages. At a certain moment, the device immediately sends a query message, and the modem forwards the query message to all LAN ports. Both A and B receive the query packet, and the set-top box A first returns the report 4 message. After receiving the report message from A, the modem will forward it on the LAN port (in most cases, the multicast message is forwarded from LAN to LAN. Both have hardware implementations, do not need to go through the protocol stack), B will not return to report 4 after receiving the report 4 message from A, that is to say, for the query message sent by the uplink device, the modem On the LAN side, only one set-top box will respond to the report 4 message. If the set-top box B receives the return message from the A back and switches the channel to 239.1.1.2 within a certain time range, the set-top box B will only send to join the 239.1.1.2. Report 4 艮文, will not send The leaving 239.1.1.1 leave packet, modem can not delete the multicast forwarding entry b, but creates a new entry c, the STB to switch the channel B forwards the multicast case shown in FIG. The uplink device sends two multicast streams 239.1.1.1 and 239.1.1.2, the set-top box A reads the program 239.1.1.1, and the set-top box B looks at the program 239.1.1.2. At this time, the _ set-top box A switches the channel to 239.1.1.3, the set-top box A first sends a leave 4 message leaving 239.1.1.1, and then sends a report message to join 239.1.1.3. After the modem receives the leave packet, it deletes the entry a. Because there is an entry b of 239.1.1.1, the modem cannot. After the packet is forwarded out on the WAN port, the modem will create an entry d according to the report packet sent by A. Since the uplink device has not received the leave message leaving 239.1.1.1, it has to send 239.1.1.1. The multicast stream, after A switches the channel, as shown in Figure 3, the uplink device sends three multicasts 3⁄4ϊ 239.1.1.1, 239.1.1.2, 239.1.1.3, 4艮 obviously 239.1.1.1 is redundant, which leads to The waste of bandwidth is more serious. If the uplink device restricts two multicast streams, since there are already two multicast streams 239.1.1.1 and 239.1.1.2, 239.1.1.3 added later cannot be sent down. Set-top box A is due to If you do not receive 239.1.1.3, it will be black, although the time of the black screen is not Over the device sends query packets with intermittent time, but this is still a user wants to see. In addition, when the PC or the set-top box is abnormally shut down, powered down, or dialed, no message will be sent, and the above faults may occur. For the related art, the LAN device often has a black screen because it does not receive a certain channel. At present, no effective solution has been proposed. SUMMARY OF THE INVENTION The present invention has been made in view of the problem that a local area network device often has a black screen because a certain channel is not received. Therefore, the main object of the present invention is to provide an implementation method and system for monitoring an Internet group management protocol, and a modem to solve the problem. The above question. In order to achieve the above object, in one aspect of the present invention, an implementation method of Internet Group Management Protocol snooping is provided. The method for implementing the Internet Group Management Protocol listening according to the present invention includes: the modem receives the leaving message from the local area network device; the modem queries the multicast table; and the modem queries the multicast table to have multiple entries in the multicast table. And saving the leaving message; the modem sending the query message to the local area network device; and, if the modem does not receive the response from the local area network device, sending the leaving message to the uplink device. Preferably, the modem saves the leaving message including: the modem creates a linked list; and the modem uses the linked list to save the leaving message. Preferably, the implementation method of the Internet group management protocol monitoring further comprises: the modem creates an identifier variable, and the identifier variable is used to identify whether the linked list is empty; wherein, when the modem receives the response from the local area network device and the identifier variable is true The modem deletes the corresponding node in the linked list. Preferably, the method for implementing the Internet Group Management Protocol monitoring further comprises: the modem determining whether the linked list is empty; and if the linked list is empty, the modem sets the identification variable to false. Preferably, after the modem sends the message to the uplink device, the method further includes: the modem deleting the node in the linked list corresponding to the leaving message. Preferably, after the modem sends the query message to the local area network device, the timing starts, wherein the modem sends the leaving message to the uplink device if the response from the local area network device is not received within the first set time. In order to achieve the above object, in another aspect of the present invention, an implementation system of Internet Group Management Protocol snooping is provided. The system includes an uplink device, a modem, and a local area network device, wherein: a local area network device, configured to send a leave message; a modem, set to receive a leave message, query The multicast table saves the leaving message and sends the query message to the local area network device when the multicast in the multicast table has multiple entries, and if the response from the local area network device is not received, The leaving message is sent to the uplink device; the uplink device is set to receive the leaving message. Preferably, the local area network device includes a set top box and a computer. In order to achieve the above object, according to another aspect of the present invention, a modem is provided. The modem includes: a receiving module configured to receive a leaving message from the local area network device; a query module configured to query the multicast table; and a saving module configured to query the multicast in the multicast table to have multiple entries And storing the leaving message; the first sending module is configured to send the query message to the local area network device; and, the second sending module is configured to send the leaving message if the response from the local area network device is not received To the uplink device. Preferably, the modem further comprises: a creating module, configured to create a linked list, wherein the linked list is used to save the leaving message; and the deleting module is set to, in response to receiving the response from the local area network device, corresponding to the linked list The node is deleted. According to the present invention, the modem receives the leaving message from the local area network device, queries the multicast table, and saves the leaving message and sends the query to the local area network device when the multicast in the multicast table has multiple entries. And, in the case that the response from the LAN device is not received, the leaving message is sent to the uplink device, which solves the problem that the LAN device often has a black screen because it does not receive a certain channel, thereby preventing the LAN device from being The black show effect is not received when a channel is not received. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, In the drawings: FIG. 1 is a schematic diagram of a set-top box A and B according to the related art joining multicast 239.1.1.1; FIG. 2 is a schematic diagram of the set-top box B switching to 239.1.1.2 according to the related art. FIG. FIG. 4 is a schematic diagram of an implementation system of the Internet Group Management Protocol listening according to the embodiment of the present invention; FIG. 4 is a schematic diagram of the system after the set-top box A is switched to 239.1.1.3; 5 is a flowchart of a method for implementing Internet group management protocol monitoring according to an embodiment of the present invention; FIG. 6 is a schematic diagram of a set top box A after switching to 239.1.1.3 according to an embodiment of the present invention; A schematic diagram of a modem; Figure 8 is a schematic illustration of a preferred embodiment of a modem in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. 4 is a schematic diagram of an implementation system of an Internet Group Management Protocol listener in an embodiment of the present invention. As shown in FIG. 4, the implementation system of the Internet Group Management Protocol monitoring includes an uplink device 10, a modem 20, and a station i or a network device 30. The local area network device 30 is configured to send and leave a message; the modem 20 is configured to receive the leaving message, query the multicast table, and save the leaving message if the multicast in the multicast table has multiple entries, and The Query message is sent to the local area network device, and if the response from the local area network device is not received, the leaving message is sent to the uplink device, and the uplink device 10 is configured to receive the leaving message. The above-mentioned local area network equipment includes a set top box and a computer. FIG. 5 is a flowchart of a method for implementing Internet group management protocol monitoring according to an embodiment of the present invention. As shown, the method includes: Step S502: The modem receives an leaving message from a local area network device. For example, the modem receives a Leave message from the LAN device via the LAN port. Step 4 gathers S 504, and the modem queries the multicast table. For example, after receiving a leave packet from a port, the modem checks the multicast mac table according to the multicast address in the leave. Step S506, the modem saves and leaves the message when it queries that the multicast in the multicast table has multiple entries. For example, the modem can save the message in the following manner: First, the modem creates a linked list; and the modem uses the linked list to save the leaving message. Step S508, the modem sends a query message to the local area network device. Step S510, the modem sends the leaving message to the uplink device without receiving the response from the local area network device. If the multicast has multiple entries, send a specific multicast query message to the corresponding LAN port (LAN device), start the timer, and cache the received Leave message; otherwise, leave the Leave message on the WAN port. Forward. Before the timer expires (timeout), if a LAN port answers the multicast query, the cached leave packet is directly discarded; otherwise, all entries of the multicast are deleted, and the cached leave 4艮The text is forwarded on the WAN port. As shown in Figure 6, when the set-top box A is switched from 239.1.1.1 to 239.1.1.3, the modem receives the leave 4艮 of 239.1.1.1, starts to query the multicast mac table, and finds that the multicast has a and b. If there are entries, the leave 4 艮 text will be cached, and the query 4艮 of 239.1.1.1 will be sent to the LAN port. Since there is no set-top box watching this program at this time, of course, the modem will not receive any response, then a and b will be All are deleted, and the previously cached leave packet is forwarded to the WAN port, so that the uplink device does not send the multicast stream of 239.1.1.1 downward after receiving the leave message, thus solving the same multicast. During the program, for some reason, the set-top box that left before did not send a leave packet and the black screen caused a waste of bandwidth. The invention only makes the modem actively send the query package when the set top box is watching the same program, and has almost no influence on the system performance. The method of the present invention can solve the problem caused by not sending a leave message in a specific case when some set top boxes play the same multicast group on the modem. Preferably, the method further includes: the modem creates an identifier variable, and the identifier variable is used to identify whether the linked list is empty, wherein if the linked list is empty, the identifier variable is false, and if the linked list is not empty, the identifier variable is true; The modem receives a response from the LAN device and, if the identification variable is true, the modem deletes the corresponding node in the linked list. The above method may further comprise: the modem determining whether the linked list is empty; and in case the linked list is empty, the modem sets the identification variable to false. After the modem sends the leaving message to the uplink device, the method may further include: the modem deleting the node in the linked list corresponding to the leaving message. In the above embodiment, the modem starts timing after transmitting the query message to the local area network device, wherein the modem sends the leaving message to the uplink device if the modem does not receive the response from the local area network device at the first set time. Specifically, the foregoing method may include the following steps: Step 1: First, the query message sent by the uplink device is cached with a variable Cquery, so that when a specific query query message needs to be sent to the LAN port, only the cached query needs to be cached. The package can modify the destination multicast address and CRC check. It is not necessary to construct a query message from beginning to end. Step 2: Create a linked list, a timer, and an identification variable. Whenever a LAN-side leave packet is received, the multicast mac table is queried. If the multicast has multiple entries, the specific port is sent to the LAN port. Multicast query 4 艮 ,, and create a linked list node, used to cache the timeout time of the leave 4 que and query and the corresponding multicast address. Step 3: As long as there is a node in the linked list, the value of the identification variable is set to true (true), the timer will start, and when the timer expires, the list is traversed, the timeout time of each node is decremented by 1, and the timeout is determined to be 0. If it is 0, the leave message saved in the node is forwarded on the WAN port, the node is deleted, and the timer is retimed. Step 4: After receiving the report packet from the LAN port, if the identifier variable is true, the traversal of the linked list according to the multicast address is found, the node is deleted, and the linked list is determined to be empty. If it is empty, the identifier variable is set to False, turns off the timer. From the above description, it can be seen that the present invention can prevent a local area network device from appearing a black screen because a certain channel is not received. It should be noted that the steps shown in the flowchart of the accompanying drawings may be performed in a computer system such as a set of computer executable instructions, and, although the logical order is shown in the flowchart, in some cases, The steps shown or described may be performed in an order different from that herein. Figure Ί is a schematic diagram of a modem in accordance with an embodiment of the present invention. As shown, the modem includes a receiving module 802, a query module 804, a saving module 806, a first sending module 808, and a second sending module 810. The receiving module 802 is configured to receive the leaving message from the local area network device; the querying module 804 is configured to query the multicast table; and the saving module 806 is configured to query the multicast in the multicast table to have multiple entries. And storing the leaving message; the first sending module 808 is configured to send the query message to the local area network device; and the second sending module 810 is configured to send the leaving message if the response from the local area network device is not received To the uplink device. Figure 8 is a schematic illustration of a preferred embodiment of a modem in accordance with the present invention. Compared with the above embodiment, the modem of this embodiment further includes: a creating module 812, configured to create a linked list, wherein the linked list is used to save the leaving message; and the deleting module 814 is configured to receive the device from the local area network In the case of a response, the corresponding node in the linked list is deleted. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or they may be Multiple modules or steps are made into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

1. An implementation method of Internet group management protocol monitoring, including:

The modem receives the leaving message from the local area network device;

The modem queries the multicast table;

The modem saves the leaving message if it queries that the multicast in the multicast table has multiple entries;

The modem transmits an inquiry message to the local area network device; and the modem transmits the leaving message to the uplink device without receiving a response from the local area network device.

2. The method according to claim 1, wherein the saving the leaving message by the modem comprises:

The modem creates a linked list;

The modem saves the leaving message by using the linked list.

3. The method according to claim 2, wherein the method further comprises:

The modem creates an identification variable, and the identification variable is used to identify whether the linked list is empty;

Wherein the modem receives a response from the local area network device and in the event that the identification variable is true, the modem deletes a corresponding node in the linked list.

4. The method according to claim 3, wherein the method further comprises:

The modem determines whether the linked list is empty;

In case the linked list is empty, the modem sets the identification variable to false.

The method according to claim 2, wherein, after the modem sends the leaving message to the uplink device, the method further includes:

The modem deletes the node in the linked list corresponding to the leaving message.

6. The method according to claim 1, wherein the modem starts timing after sending a query message to the local area network device, wherein the modem does not receive a response from the local area network device at the first set time. In the case, the leaving message is sent to the uplink device.

7. A modem that includes:

a receiving module, configured to receive a leaving message from a local area network device;

The query module is configured to query the multicast table; and the saving module is configured to save the leaving message if the multicast in the multicast table is queried to have multiple entries;

a first sending module, configured to send a query to the local area network device; and a second sending module configured to send the leaving message to the upper device without receiving a response from the local area network device Connected devices.

8. The modem according to claim 7, further comprising:

Creating a module, configured to create a linked list, wherein the linked list is used to save the leaving message;

And deleting the module, configured to delete the corresponding node in the linked list if receiving a response from the local area network device.

9. An implementation system for monitoring Internet Protocol Management Protocol, comprising an uplink device, a modem, and a local area network device, wherein:

The local area network device is configured to send a leave message;

The modem is configured to receive the leaving message, query a multicast table, and save the leaving message and the local area network device when querying that the multicast in the multicast table has multiple entries Sending a query message, and sending the leaving message to the uplink device if the response from the local area network device is not received;

The uplink device is configured to receive the leaving message. The system of claim 9, wherein the local area network device comprises a set top box and a computer.