CN101964733A - Method and system for implementing internet group management protocol snooping and modem - Google Patents

Abstract

The invention discloses a method, a system and a modem for realizing monitoring of an Internet group management protocol. Wherein, the implementation method of the Internet group management protocol monitoring includes: the modem receives the leaving message from the LAN device, queries the multicast table, and saves the leaving message when it is found that the multicast in the multicast table has multiple entries. , sending a query message to the local area network device, and sending a leave message to the uplink device if no response is received from the local area network device. Through the present invention, it is possible to prevent a black screen from appearing on a local area network device because a certain channel cannot be received.

Description

Implementation method, system, and modem of Internet group management protocol monitoring

technical field

The present invention relates to the field of communications, in particular to a method, system and modem for implementing Internet Group Management Protocol Snooping (IGMPSnooping for short). the

Background technique

At present, the IGMP Snooping of the general Modem (modem) is to maintain a multicast address by listening to the IGMP messages communicated between the local area network (Local Area Network, referred to as LAN) side users and (Wide Area Network, referred to as WAN) WAN port uplink equipment. The forwarding table corresponding to each port on the LAN side. After receiving the multicast data packet, look up the table according to the multicast address to determine which LAN ports should forward the multicast packet. The main process for IGMPv2 messages is as follows:

When receiving an IGMP report (response) message from a pc (computer), stb (set-top box), etc. from a certain LAN port, (using multicast address, LAN port, source mac) to find out whether the multicast mac table already exists If it exists, update the aging time of the forwarding entry. If it does not exist, create a corresponding forwarding entry based on the multicast address, the LAN port number that received the report message, the source mac of the device that sent the report packet, and the aging time, etc., and add it to multicast mac table, and forward the message to the WAN port; when an IGMP leave message (leave message) is received from a LAN port, the same (multicast address, LAN port, source mac) search group Whether the forwarding entry already exists in the multicast mac table, if it exists, delete the entry from the multicast mac table, and only use the multicast address to find out whether there are other entries. If it exists, it means that there are other LAN ports that need the multicast. The IGMPleave packet will be discarded and not forwarded to the WAN port. If there are no other entries of the multicast, the IGMP leave message will be forwarded to the WAN port; port forwarding; in addition, when the aging time of an entry is decremented to 0, the entry is deleted. the

It can be seen from the basic processing process of IGMP snooping above that 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 will forward the IGMP leave message to the WAN port, which will cause the uplink device to stop sending the corresponding multicast A message to the WAN port of the modem, then the other one still needs the multicast message The port also cannot receive the message of multicast A; in addition, it can be seen that the IGMP report message from any LAN port can be received by other LAN port devices, and the modem itself does not actively send IGMP query messages. It just transparently transmits the query message received from the WAN port to all LAN ports. the

In practical application, the inventor found that some set-top boxes in related technologies have the following characteristics in the way of processing multicast, as follows: a typical networking method is shown in Figure 1, set-top boxes A and B both join the multicast 239.1.1.1, and the multicast mac There are two entries a and b in the forwarding table. The uplink device sends the IGMP query message regularly. At a certain moment, the uplink device just sends the query message. The modem forwards the query message on all LAN ports. Set-top box A Both set-top box A and B have received the query packet, and the set-top box A returns the report message first. After the modem receives the report message returned by A, it will forward it on the LAN port (in most cases, this kind of multicast message is forwarded from LAN to LAN. It is implemented by hardware and does not need to go through the protocol stack), B will not return the report message after receiving the report message from A, that is to say, for the query message sent by the uplink device, the LAN side of the modem only There will be a set-top box responding to the report message. If set-top box B switches the channel to 239.1.1.2 within a certain time range after receiving the report message from A, set-top box B will only send a report message to add 239.1.1.2. The leave message for leaving 239.1.1.1 will not be sent, and the modem will not delete the corresponding multicast forwarding entry b, but will create a new entry c. The multicast forwarding situation after the above-mentioned set-top box B switches channels is shown in Figure 2. the

The uplink device sends two multicast streams 239.1.1.1 and 239.1.1.2. Set-top box A watches program 239.1.1.1, and set-top box B watches program 239.1.1.2. At this time, suppose set-top box A switches the channel to 239.1.1.3. Set-top box A first Send a leave message to leave 239.1.1.1, and then send a report message to join 239.1.1.3, the modem deletes entry a after receiving the leave packet, because there is still entry b of 239.1.1.1, so the modem cannot wrap leave in The WAN port forwards it out, and the modem will also create entry d according to the report message sent by A. Since the uplink device has not received the leave message leaving 239.1.1.1, it has to send the multicast stream of 239.1.1.1 down, A After switching channels, as shown in Figure 3, the uplink device sends three multicast streams 239.1.1.1, 239.1.1.2, and 239.1.1.3. Obviously, 239.1.1.1 is redundant, which leads to a waste of bandwidth, and even more serious If the uplink device restricts two multicast streams, because there are already two multicast streams 239.1.1.1 and 239.1.1.2, the 239.1.1.3 added later cannot be sent down, and the set-top box A cannot receive 239.1.1.3. There will be a black screen, although the time of the black screen will not exceed the interval time between the query packet sent by the uplink device, but this is still unwilling to see for the user. In addition, when the PC or set-top box is abnormally shut down, power-off, or disconnects the network cable, it will not send a leave message, and the above faults may occur. the

Aiming at the problem in the related art that the LAN device often has a black screen because it cannot receive a certain channel, no effective solution has been proposed yet. the

Contents of the invention

The present invention is proposed aiming at the problem that the LAN equipment often appears black screen because it cannot receive a certain channel. For this reason, the main purpose of the present invention is to provide a method, system and modem for realizing monitoring of the Internet group management protocol, so as to solve the above-mentioned problems . the

In order to achieve the above purpose, according to one aspect of the present invention, a method for implementing IGMP monitoring is provided. the

According to the implementation method of Internet group management protocol monitoring of the present invention, comprising: the modem receives the leaving message from the local area network equipment; the modem queries the multicast table; the modem saves the A leave message; the modem sends a query message to the LAN device; and, when the modem does not receive a response from the LAN device, sends the leave message to the uplink device. the

In order to achieve the above purpose, according to another aspect of the present invention, a system for implementing IGMP monitoring is provided. The system includes an uplink device, a modem and a LAN device, among which: the LAN device is used to send the leaving message; the modem is used to receive the leaving message and query the multicast table. In the case of entries, save the leave message, and send a query message to the LAN device, and if no response is received from the LAN device, send the leave message to the uplink device; the uplink device is used to receive leave the message. the

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, used to receive the leaving message from the LAN device; a query module, used to query the multicast table; a saving module, used to query the multicast table in the case that there are multiple entries , save the leaving message; the first sending module is used to send the query message to the LAN device; and the second sending module is used to send the leaving message to the uplink if no response is received from the LAN device equipment. the

Through the present invention, the modem is used to receive the leaving message from the LAN device, query the multicast table, and when the multicast in the multicast table is found to have multiple entries, save the leaving message, and send the query message to the LAN device , and in the case of not receiving a response from the LAN device, the leave message is sent to the uplink device, which solves the problem that the LAN device often has a black screen because it cannot receive a certain channel, and thus prevents the LAN device from The effect of a black screen appears because a certain channel cannot be received. the

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

Fig. 1 is the synoptic diagram that set-top box A and B all join multicast 239.1.1.1 according to related technology;

Figure 2 is a schematic diagram of the set-top box B switched to 239.1.1.2 according to the related technology

Fig. 3 is a schematic diagram after the set-top box A is switched to 239.1.1.3 according to the related technology;

Fig. 4 is the schematic diagram of the realization system of the Internet group management protocol monitoring according to the embodiment of the present invention;

Fig. 5 is the flow chart of the realization method that the Internet Group Management Protocol monitors according to the embodiment of the present invention;

Fig. 6 is a schematic diagram after the set-top box A switches to 239.1.1.3 according to an embodiment of the present invention;

Figure 7 is a schematic diagram of a modem according to an embodiment of the present invention;

Figure 8 is a schematic diagram of a preferred embodiment of a modem in accordance with the present invention. the

Detailed ways

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples. the

Fig. 4 is a schematic diagram of a system for implementing IGMP snooping according to an embodiment of the present invention. the

As shown in FIG. 4 , the system for implementing IGMP monitoring includes an uplink device 10 , a modem 20 and a LAN device 30 . the

Wherein, the LAN device 30 is used to send the leaving message; the modem 20 is used to receive the leaving message, query the multicast table, and save the leaving message when the multicast in the multicast table is found to have multiple entries, and Send a query message to the LAN device, and if no response is received from the LAN device, send the leave message to the uplink device, and the uplink device 10 is used to receive the leave message. the

The aforementioned LAN devices include set-top boxes and computers. the

Fig. 5 is a flowchart of a method for implementing IGMP snooping according to an embodiment of the present invention. As shown, the method includes:

Step S502, the modem receives the leaving message from the LAN device. the

For example, a modem receives leave messages from LAN devices via a LAN port. the

Step S504, the modem queries the multicast table. the

For example, after a modem receives a leave message from a certain port, it checks the multicast mac table according to the multicast address in the leave. the

In step S506, the modem saves the leave message when it finds that there are multiple entries in the multicast table. the

For example, a modem can store leave messages in the following ways:

First, the modem creates the linked list; and

The modem uses a linked list to save the leaving message. the

Step S508, the modem sends a query message to the LAN device. as well as

Step S510, if the modem does not receive a response from the LAN device, the modem sends the leaving message to the uplink device. the

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. the

Before the timer expires (timeou), if there is a LAN port answering the multicast query message, the cached leave message will be discarded directly; otherwise, all entries of the multicast will be deleted, and the cached leave message will be WAN port forwarding. the

As shown in Figure 6, when the set-top box A switches from 239.1.1.1 to 239.1.1.3, the modem receives the leave message of 239.1.1.1, starts to query the multicast mac table, and finds that the multicast has a and b If the entry exists, the leave message will be cached, and the query message of 239.1.1.1 will be sent to the LAN port. Since no set-top box is watching this program at this time, of course the modem cannot receive any response, and both a and b will be deleted. And forward the previously cached leave packet to the WAN port, so that the uplink device will not send the 239.1.1.1 multicast stream downward after receiving the leave message, which solves the problem of watching the same multicast program. For some reason, the set-top box that left before did not send a leave packet, which caused a black screen and a waste of bandwidth. the

The invention only allows the modem to actively send query packets when the set-top box is watching the same program, and has almost no influence on system performance.

Through the above method, the present invention can solve the problem caused by protecting some set-top boxes from not sending leave messages under certain circumstances when playing the same multicast group on the modem. the

Preferably, the above method further includes: the modem creates an identification variable; wherein, when the modem receives the response from the LAN device and the identification variable is true, the modem deletes the corresponding node in the linked list. the

The above method may further include: the modem judging whether the linked list is empty; and if the linked list is empty, the modem sets the identification variable as false. the

After the modem sends the leave message to the uplink device, the above method may further include: the modem deletes the node corresponding to the leave message in the linked list. the

In the above embodiment, after the modem sends the query message to the LAN device, it starts counting. If the modem does not receive a response from the LAN device at the first time, it sends the leaving message to the uplink device. the

Specifically, the above method may include the following steps:

Step 1, first cache the query message sent by the uplink device in a variable Cquery, so that when you need to send a specific query message to the LAN port, you only need to modify the cached query package for the destination multicast address and CRC check. Yes, there is no need to construct a query message from beginning to end. the

Step 2. Create a linked list, a timer and an identification variable. Whenever a leave message from the LAN side is received, the multicast mac table is queried. If it is found that the multicast has multiple entries, a specific message is sent to the LAN port. Multicast the query message, and create a linked list node, which is used to cache the timeout time of the leave message and query and the corresponding multicast address. the

Step 3, as long as there are nodes in the linked list and the value of the identification variable is set to true (true), the timer will start, and when the timer expires, the linked list will be traversed, the timeout time of each node will be reduced by 1, and it will be judged whether the timeout is 0 , if it is 0, the leave message saved in the node will be forwarded on the WAN port, the node will be deleted, and the timer will be reset. the

Step 4, receive the report message from the LAN port, if the identification variable is true, then traverse the linked list according to the multicast address, delete the node if found, and judge whether the linked list is empty, if it is empty, set the identification variable to false (false), turn off the timer. the

From the above description, it can be seen that the present invention can prevent the LAN device from appearing black screen due to failure to receive a certain channel. the

It should be noted that the steps shown in the flowcharts of the accompanying drawings may be performed in a computer system, such as a set of computer-executable instructions, and that although a logical order is shown in the flowcharts, in some cases, The steps shown or described may be performed in an order different than here. the

FIG. 7 is a schematic diagram of a modem according to an embodiment of the present invention. As shown in the figure, 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

Wherein, the receiving module 802 is used to receive the leaving message from the LAN device; the query module 804 is used to query the multicast table; the preservation module 806 is used to query the multicast in the multicast table when there are multiple entries Next, save the leaving message; the first sending module 808 is used to send a query message to the LAN device; and the second sending module 810 is used to send the leaving message when no response is received from the LAN device Uplink equipment. the

Figure 8 is a schematic diagram of a preferred embodiment of a modem in accordance with the present invention. the

Compared with the above-mentioned embodiment, the modem of this embodiment also includes: a creation module 812, which is used to create a linked list, wherein, the linked list is used to save the leaving message; In the case of a response, delete the corresponding node in the linked list. the

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned present invention can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network formed by multiple computing devices Optionally, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, or they can be made into individual integrated circuit modules, or they can be integrated into Multiple modules or steps are fabricated into a single integrated circuit module to realize. As such, the present invention is not limited to any specific combination of hardware and software. the

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims (10)

1. A method for implementing Internet Group Management Protocol monitoring, characterized in that, comprising: The modem receives the leaving message from the LAN device; The modem queries the multicast table; The modem saves the leave message when it is found that the multicast in the multicast table has multiple entries; The modem sends a query message to the LAN device; and When the modem does not receive a response from the LAN device, the modem sends the leave message to the uplink device. 2. The method according to claim 1, wherein the modem saving the leaving message comprises: said modem creates a linked list; and The modem saves the leaving message by using the linked list. 3. The method according to claim 2, wherein the method further comprises: said modem creates an identification variable; Wherein, when the modem receives the response from the LAN device and the identification variable is true, the modem deletes the corresponding node in the linked list. 4. method according to claim 3, is characterized in that, described method also comprises: The modem determines whether the linked list is empty; and In case the linked list is empty, the modem sets the identification variable to false. 5. The method according to claim 2, characterized in that, after the modem sends the leaving message to the uplink device, the method further comprises: The modem deletes the node corresponding to the leaving message in the linked list. 6. The method according to claim 1, wherein the modem starts timing after sending the query message to the LAN device, wherein the modem does not receive a response from the LAN device at the first time In other cases, the leave message is sent to the uplink device. 7. A modem, characterized in that, comprising: A receiving module, configured to receive a leaving message from a LAN device; Query module, used for querying multicast table; A saving module, configured to save the leaving message when it is found that the multicast in the multicast table has multiple entries; A first sending module, configured to send a query message to the LAN device; and The second sending module is configured to send the leaving message to the uplink device when no response is received from the LAN device. 8. The modem according to claim 7, further comprising: A creating module, configured to create a linked list, wherein the linked list is used to save the leaving message; and A deletion module, configured to delete the corresponding node in the linked list when a response from the LAN device is received. 9. A realization system of Internet Group Management Protocol monitoring, characterized in that it includes an uplink device, a modem and a local area network device, wherein: The LAN device is configured to send a leaving message; The modem is configured to receive the leaving message, query the multicast table, and store the leaving message when it is found that there are multiple entries in the multicast table, and send the leaving message to the LAN device Querying a message, and sending the leaving message to the uplink device if no response is received from the LAN device; The uplink device is configured to receive the leave message. 10. The system according to claim 9, wherein the local area network device comprises a set-top box and a computer.

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