WO2009018770A1 - Method and router for positioning the last hop router and multicasting routing track - Google Patents

Abstract

The invention discloses a last-hop positioning router, and a multicast route tracking method and the router. The technical field of this invention is network communication. The positioning method includes the following steps: the router receives the inquiry message, which is sent to the unicast receiver by the multicast route tracking router; the router judges whether it is in the network segment belong to received address, and does not transmit multicast data flow; if it is, judging whether the network segment has a active multicast number; if it is, amending the inquiry message and transmitting to this network segment. The router includes the receiving module, the judging module, and the positioning module. The tracking method includes the following steps: positioning the last-hop router based the method as noted above; transmitting the request message to the upper hop along the reverse path to the source address; transmitting the response message to the pointed address of the inquiry message, after the first hop router connected the multicast source receiving the request message. The invention can exactly locate the last-hop router in multicast router tracking process, and increase the success ratio for positioning the last hop router and multicast router tracking.

Description

 Method and router for locating last hop router and multicast route tracking

 The present invention relates to the field of network communications, and in particular, to a method, a router, and a multicast route tracking method for locating a last hop router in multicast route tracking.

 Say

Background technique

 Mtracert (Multicast Trace Route) is a fault diagnosis tool for multicast routing protocols. It collects traffic statistics of multicast routes, provides abnormal node information, and collects hop-by-hop (S, G) traffic. Statistics and other functions. The development of the Mtracert tool follows a mechanism for tracking the network path through which a group of books broadcasts data from a multicast source to a specific destination receiver: Enter the mtrace command on the router (or network management host) that performs multicast route tracking, which specifies Source address, destination address, and multicast group; the router sends an IGMP (Internet Group Management Protocol) Tracert Query message to the last hop router (Last-Hop) of the destination address, the last hop After receiving the packet, the router adds the response data block of the hop (including the interface address and packet statistics of the hop), and then sends an IGMP Tracert Request to the upstream hop router along the reverse multicast path to the source address. Request) a message; after each hop router receives the request message, it adds the response data block of the hop and forwards the request message to the source; when the first hop router connected to the multicast source receives After the request message adds the response data block of the hop, it responds to the response address specified in the query message (Response Addr Ess) Sends an IGMP Tracert Response message.

 For example, see Figure 1. Using the Mtracert tool, enter the mtrace command on the querier, router Q1, specifying the IP address S of the source PC1, the IP address D of the receiver PC2, and the multicast group address G. The router Q1 sends a query message to the destination address D. After receiving the query message, the last hop router R4 sends a request message to the upstream hop router R2 along the reverse multicast path to the source address, and in the message. Adding the information of this hop, R2 also adds its own hop information after receiving it, and continues to send the request message to the upstream hop router R1, and so on. When the first hop router R1 connected to the multicast source receives the request packet, it adds its own hop information, and then sends a response packet to the response address (may be router Q1) specified in the Query message.

During the multicast route tracking process, the querier needs to send the Query message to the last hop router of the destination address. Therefore, how to locate the last hop router becomes a key issue in the multicast route tracking process. Generally used in the prior art The following method is used to locate the last hop router: The router that performs multicast route tracking (that is, the querier) sends a query message to the router in the network. The router that receives the query message determines whether it meets the following two conditions: At least one The interface running the multicast belongs to the same network segment as the destination address. The multicast data stream from the specified source is forwarded to the network segment. If both conditions are met, then you are the last hop router, otherwise it is not. If the router that receives the Query message finds that it is not the last hop router, it further determines the type of the received Query message. If the Query message is a unicast message, it sends a response message with the error code WRONG_LAST_HOP. After the querier receives the response packet, the querier continues to send the Query message after resending the sender and re-locates the last hop router. If the Query message is a multicast packet, the Query message is discarded. deal with.

 When the querier sends the Query message, the following sending mode can be used:

 When the last hop router is unknown, and the multicast source address S, the multicast receiver address D, and the multicast group address G are known, the querier unicasts a query message with the destination address D to the receiver, and the query If the packet carries the Router Alert IP option, the query packet may be received by the last hop router on the shared network segment where the receiver resides.

 In the process of implementing the present invention, the inventors have found that the above prior art has at least the following disadvantages:

 The unicast path and the multicast path may be different. Therefore, the Query message cannot be accurately sent to the multicast hop router. For example, referring to FIG. 1, if the unicast path from the querier Q1 to the receiver PC2 is: Q1->R3->R5->PC2, the actual path of the multicast data stream from the multicast source PC1 to PC2 is: PC1->R1->R2->R4->PC2, that is, R5 is the unicast last hop router of PC2, and R4 is the multicast last hop router of PC2, so the query message will be unicast last hop router. R5 receives, R5 finds that it is not the real multicast last hop router, it will send a response message with the error code WR0NG_LAST_H0P to the querier, and the real multicast last hop router R4 does not receive the query message. Summary of the invention

 In order to accurately locate the last hop router in the multicast route tracking, the embodiment of the present invention provides a method and a router for locating the last hop router in the multicast route tracking. The technical solution is as follows:

 In one aspect, a method for locating a last hop router in multicast route tracking, the method includes:

 The router receives the query message that the router performing the multicast route tracking unicasts to the receiver;

 The router determines whether it is in the network segment to which the receiver address belongs, and does not forward the multicast data stream. If yes, it determines whether there is an active multicast member in the network segment, and if so, the modification The queried message is forwarded to the network segment, and the last hop router located in the network segment receives the modified query message.

In another aspect, a router includes: a receiving module, configured to receive a query message that the router performing the multicast route tracking unicasts to the receiver, and a determining module, configured to determine whether the router is in the network segment to which the receiver address belongs, and does not forward the multicast Data stream, if yes, determining whether there is an active multicast member in the network segment;

 The locating module is configured to: when the determining module determines that there is an active multicast member in the network segment, modify the Query message received by the receiving module and forward the Query message to the network segment.

 In order to improve the success rate of the multicast route tracking, the embodiment of the present invention further provides a method for multicast route tracking, where the method includes:

 The router that performs multicast route tracking unicasts the query message to the receiver.

 After receiving the query message, the router determines whether it is in the network segment to which the receiver address belongs, and does not forward the multicast data stream. If yes, it determines whether there is an active multicast member in the network segment. If yes, modify the query message and forward it to the network segment;

 After receiving the modified query message, the last hop router in the network segment sends a multicast tracking request message to the upstream hop router along the reverse multicast path to the multicast source address.

 After receiving the request packet, the first hop router connected to the multicast source sends a multicast tracking response packet to the response address specified in the query packet.

 The embodiment of the present invention determines whether the router that receives the query message is in the same network segment as the receiver, does not forward the multicast data stream, and whether there is an active multicast member in the network segment. If yes, modify the query. After the packet is forwarded to the network segment, the router can accurately locate the last hop router in the multicast route tracking, which reduces the number of probes sent by the query mode during positioning, which greatly improves the success of multicast route tracking. rate. After the last hop router is successfully located, multicast route tracking is performed, which greatly improves the accuracy, reliability, and success rate of multicast route tracking. DRAWINGS

 1 is a schematic diagram of a multicast routing tracking networking in the prior art;

 2 is a flowchart of a method for locating a last hop router in multicast route tracking according to an embodiment of the present invention; FIG. 3 is a structural diagram of a router according to an embodiment of the present invention;

 FIG. 4 is a flowchart of a method for multicast route tracking according to an embodiment of the present invention. detailed description

The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The embodiment of the present invention determines whether the router that receives the query message is in the same network segment as the receiver, does not forward the multicast data stream, and whether there is an active multicast member in the network segment. If yes, modify the query. After the packet is forwarded to the network segment, the last hop router is accurately located in the multicast route tracking. This reduces the number of probes sent by the query packet during positioning, and improves the success rate of the last hop router. .

 Referring to FIG. 2, an embodiment of the present invention provides a method for locating a last hop router in multicast route tracking, which specifically includes the following steps:

 Step 101: In the multicast route tracking, the router performing the multicast route tracking unicasts the query message to the multicast receiver. On the router that performs multicast route tracking, enter the mtrace command. The mtrace command specifies the multicast source address, multicast receiver address, and multicast group address. The router that performs multicast route tracking follows the unicast path according to the mtrace command. Send a query message to the network.

 Step 102: The router in the network receives the query message to determine whether it is the last hop router. If yes, the location is successful, and the multicast route tracking process is started until the multicast route tracking is completed; otherwise, step 103 is performed; Step 103: The router determines whether it is in the network segment to which the multicast receiver address belongs, and does not forward the multicast data stream; if yes, that is, both conditions are met, step 104 is performed; otherwise, step 107 is performed.

 The foregoing judgment may be specifically: determining whether the interface is directly connected to the network segment to which the multicast receiver address belongs, and the interface is not in the outbound interface list of the multicast forwarding entry.

 Step 104: Determine whether there is an active multicast member in the network segment. If yes, execute step 105. At this time, the router may be a loser; otherwise, execute step 107.

 Step 105: Modify the query packet received by the router, and then forward the modified query packet to the network segment. The modification query message is specifically:

 If the destination address in the IP header of the received query packet is changed to the address of all multicast routers, the modified query packet can be received by all multicast routers in the network segment.

 Further, the TTL (Time To Live) of the received query message may be modified, and the number of times of the modified query message is limited. For example, the TTL of the query packet is changed to 1, and the modified query message is modified. It can only be forwarded once. After the query packet is received by the router on the network segment, it cannot be forwarded again. After the last hop router is successfully located, the query packet is forwarded in the network segment, thus avoiding The message is flooding.

 When the modified query packet is forwarded, the query packet can be directly forwarded from the interface connected to the network segment by the router.

Step 106: The multicast last hop router in the network segment receives the modified query message, so that the last hop router is located, and the location is successful, and the multicast route tracking process is started until the multicast route tracking is completed. After receiving the modified query message, the last hop router determines whether it is the last hop router, that is, whether it has at least one interface running multicast and the receiver address belong to the same network segment, and will be from the specified source. The multicast data stream is forwarded to the network segment. If both conditions are met, then it is the last hop router, otherwise it is not the last hop router.

 Step 107: The router that receives the query message returns a response message containing the error code (WRONG_LAST_HOP) to the response address specified in the query message.

 For example, referring to Figure 1, the querier Q1 unicasts the Query message to the multicast receiver PC2. When the router R5 receives it, it finds that it has an interface IF0 directly connected to the network segment to which the PC2 address belongs, but the interface is not in the corresponding In the outbound interface list of the multicast forwarding entry, the multicast data stream is not forwarded by itself. After the network member is found to have active group members, the destination address in the IP header of the received query packet is changed. Change the address of all multicast routers, for example 224.0.0.2, to TTL

1, and then forwarded from the above interface IF0, the real last hop router R4 in the network segment will receive the modified query message, so that the last hop router can be located.

 In this embodiment, it is determined whether the router that receives the query message is in the same network segment as the receiver, and does not forward the multicast data stream, and whether there is an active multicast member in the network segment. If yes, modify the query report. The message is forwarded to the network segment, so that the last hop router is accurately located in the multicast route tracking, which reduces the number of probes for the query mode when the positioning is performed, which greatly improves the success of locating the last hop router. The rate also improves the success rate of multicast route tracking. The TTL of the Query message is modified to limit the number of times the queried message is forwarded. This prevents the last hop from being successfully located. The Query message is also forwarded in the network, thus preventing packet flooding.

 Referring to FIG. 3, an embodiment of the present invention further provides a router, including:

 The receiving module 301 is configured to receive, by the router that performs the multicast route tracking, the unicast to the receiver, and the determining module 302 is configured to determine whether the router is in the network segment to which the receiver address belongs, and does not forward the multicast data stream. If yes, determine whether there is an active multicast member in the network segment;

 The locating module 303 is configured to: when the determining module 302 determines that there is an active multicast member in the network segment, modify the Query message received by the receiving module 301 and forward the Query message to the network segment.

 The positioning module 303 may specifically include:

 a modifying unit, configured to: when the determining module 302 determines that there is an active multicast member in the network segment, modify the destination address of the query packet received by the receiving module 301 to the address of all the multicast routers;

 The forwarding unit is configured to forward the modified query message to the network segment to which the receiver address belongs.

Further, in order to prevent the flooding of the message, the modifying unit is further configured to modify the lifetime of the query message received by the receiving module 301 when the determining module determines that there is an active multicast member in the network segment. In addition, the foregoing router may further include:

 The response module is configured to: when the determining module determines that the router is not in the network segment to which the receiver address belongs, or when there is no active multicast member in the network segment, send a response packet containing the error code to the query packet. The specified response address.

 In this embodiment, the determining module determines whether the router is in the same network segment as the receiver, and does not forward the multicast data stream, and whether there is an active multicast member in the network segment. If yes, the query module modifies the query packet. After being forwarded to the network segment, the multicast routing tracking is used to accurately locate the last hop router, which reduces the number of probes for querying the packet transmission mode, and greatly improves the success rate of multicast route tracking. The TTL of the Query message is modified to limit the number of queried packets. This prevents the last hop from being successfully located. The Query message is also forwarded in the network, thus preventing packet flooding.

 Referring to FIG. 4, an embodiment of the present invention further provides a method for multicast route tracking, which specifically includes the following steps: Step 201: A router that performs multicast route tracking unicasts a query message to a multicast receiver.

 You can enter the mtrace command on the router that performs multicast route tracking, which specifies the source address, destination address, and multicast group. The destination address is the address of the receiver.

 Step 202: After receiving the query message, the router determines whether it is the last hop router. If yes, step 207 is performed; otherwise, step 203 is performed.

 Step 203: The router determines whether it is in the network segment to which the multicast receiver address belongs, and does not forward the multicast data stream; if yes, that is, both conditions are met, step 204 is performed; otherwise, step 209 is performed.

 The foregoing judgment may be specifically: determining whether the interface is directly connected to the network segment to which the multicast receiver address belongs, and the interface is not in the outbound interface list of the multicast forwarding entry.

 Step 204: Determine whether there is an active multicast member in the network segment. If yes, execute step 205, where the router may be a loser; otherwise, execute step 209.

 Step 205: Modify the query message received by the router, and then forward the modified query message to the network segment. The modification query message is specifically:

 If the destination address in the IP header of the received query packet is changed to the address of all multicast routers, the modified query packet can be received by all multicast routers in the network segment.

 Further, the TTL of the received query message can be modified to prevent the flood of the message.

 When the modified query packet is forwarded, the query packet can be directly forwarded from the interface connected to the network segment by the router.

Step 206: The multicast last hop router in the network segment receives the modified query message, so as to locate the last hop router, that is, the location is successful, and the multicast route tracking process begins. Step 207: The last hop router sends a multicast tracking request message (IGMP Tracert Request) to the upstream hop router along the reverse multicast path to the multicast source address. If the previous hop router is not the first to connect to the multicast source, The hop router continues to send the multicast tracking request message to the upstream hop router along the reverse multicast path to the multicast source address.

 Before the last hop router or other router sends a request packet to the upstream hop router, the response data block of the hop (including the interface address of the hop and the packet statistics) may be added to the request packet.

 Step 208: After receiving the request packet, the first hop router that connects the multicast source sends a multicast tracking response packet (IGMP Tracert Response) to the response address specified in the query packet to complete the multicast route tracking.

 The first hop router may also add a response data block of the hop in the request message, and then send the request message. Step 209: The router that receives the query message returns a response message containing the error code (WR0NG_LAST_H0P) to the response address specified in the query message.

 In this embodiment, it is determined whether the router that receives the query message is in the same network segment as the receiver, and does not forward the multicast data stream, and whether there is an active multicast member in the network segment. If yes, modify the query report. The message is forwarded to the network segment to accurately locate the last hop router, and then implement multicast route tracking, which improves the accuracy and reliability of multicast route tracking, and reduces the query message when the last hop router is located. The number of probes in the transmission mode greatly improves the success rate of the last hop router, and also improves the success rate of multicast route tracking. The TTL of the Query message is modified to limit the number of times the queried message is forwarded. This prevents the last hop from being successfully located. The Query message is also forwarded in the network, thus preventing packet flooding.

 The embodiments of the present invention can be implemented by software, and the corresponding software can be stored in a readable storage medium, such as a Flash, a CF card or a hard disk of a router.

 The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., which are within the spirit and scope of the present invention, should be included in the protection of the present invention. Within the scope.

Claims

Claim A method for locating a last hop router in a multicast route tracking, the method comprising: the router receiving a query message that the router performing the multicast route tracking unicasts to the receiver;  If the router is in the network segment to which the receiver address belongs, and does not forward the multicast data stream, determine whether there is an active multicast member in the network segment to which the receiver address belongs, and if so, modify the network. After the Query message is forwarded, it is forwarded to the network segment to which the receiver address belongs, so that the last hop router in the network segment to which the receiver address belongs receives the modified query message.  The method for locating the last hop router in the multicast route tracking according to claim 1, wherein the step of modifying the query message is specifically:  Modify the destination address of the query packet to the address of all multicast routers.  The method for locating the last hop router in the multicast route tracking according to claim 2, wherein the step of modifying the query message further comprises:  The lifetime of the query packet is modified, and the number of times the modified query packet is forwarded is limited.  The method for locating a last-hop router in the multicast route tracking according to claim 1, wherein the method further includes:  If the router is not in the network segment to which the receiver address belongs, or there is no active multicast member in the network segment to which the receiver address belongs, the response packet containing the error code is sent to the query message. The specified response address.  A router, characterized in that the router comprises:  a receiving module, configured to receive, by the router performing multicast routing tracking, a unicast query message to the receiver;  a determining module, configured to determine whether the router is in a network segment to which the receiver address belongs, and does not forward the multicast data stream, and if yes, determine whether there is an active group in the network segment to which the receiver address belongs Broadcast member  a locating module, configured to: when the determining module determines that the active multicast member exists in the network segment to which the receiver address belongs, modify the query message received by the receiving module, and then forward the query message to the The network segment to which the receiver address belongs.  The router according to claim 5, wherein the positioning module specifically includes:  a modifying unit, configured to: when the determining module determines that there is an active multicast member in the network segment to which the receiver address belongs, modify the destination address of the query packet received by the receiving module to all groups Broadcast router address;  And a forwarding unit, configured to forward the modified query message to the network segment to which the receiver address belongs. The router according to claim 6, wherein the modifying unit is further configured to: when the determining module determines that there is an active multicast member in a network segment to which the receiver address belongs, Receiving the query report received by the module The lifetime of the text is changed to 1.  The router according to claim 5, wherein the router further comprises:  a response module, configured to: when the determining module determines that the router is not in the network segment to which the receiver address belongs, or when it is determined that there is no active multicast member in the network segment to which the receiver address belongs, A response message containing an error code is sent to the response address specified in the query message.  A method for multicast route tracking, the method comprising:  The router that performs multicast route tracking unicasts the query message to the receiver.  The router receives the query message, and if the router is in the network segment to which the receiver address belongs, and does not forward the multicast data stream, it is determined whether there is an active group in the network segment to which the receiver address belongs. Broadcast member, if yes, modify the query message and forward it to the network segment to which the receiver address belongs;  After receiving the modified query message, the last hop router in the network segment to which the receiver address belongs sends a multicast tracking request report to the upstream hop router along the reverse multicast path to the multicast source address. Text  After receiving the request packet, the first hop router connected to the multicast source sends a multicast tracking response packet to the response address specified in the query packet.  The method for modifying the multicast routing according to claim 9, wherein the step of modifying the query message is specifically:  The address of 0 of the query message is modified to the address of all multicast routers.  The method for modifying the multicast routing according to claim 10, wherein the step of modifying the query message further comprises:

 The method for multicast route tracking according to claim 9, wherein the method further comprises: if the router is not in a network segment to which the receiver address belongs, or the receiver address belongs to If there is no active multicast member in the network segment, a response packet containing the error code is sent to the response address specified in the query message.