CN100484078C - A method to realize VPN multicast - Google Patents

Abstract

The present invention relates to a method for realizing VPN multicast in a multicast domain, comprising: a group management router in the VPN network side periodically inquires about the current receiver PEs list; The coverage is calculated; the VPN network side judges whether the coverage value is less than the preset coverage threshold. If yes, the VPN network side establishes a public network multicast distribution tree, and the receiving members in the current multicast group are The coverage of the public network multicast distribution tree is greater than or equal to a preset coverage threshold. In the present invention, through the calculation of the coverage, in the case that the coverage does not meet the conditions, by selecting or creating a P-Tree method to meet the requirements of the coverage, it avoids the sparse distribution of receiving member sites and reduces the bandwidth. waste.

Description

A Method of Realizing VPN Multicast

technical field

The invention relates to a multicast method, in particular to a method for realizing VPN multicast in a multicast domain. It belongs to the field of communication.

Background technique

In the network, each user access point is called a site (Site). The VPN (Virtual Private Network) network includes the following entities: Provider Edge Router (PE for short) is used to provide users with network interfaces in the backbone network of operators, store virtual routing (VirtualRouting Forwarding Instance, VRF) forwarding , process VPN-IPv4 routing, and access VPN subnets located at various sites, which are the main implementation parts of VPN; Customer Edge Router (CE for short), the network interface that accesses the backbone network of the operator in the user VPN site, Converge the private network routes of this site, publish and receive user network routes; the core router of the operator network (referred to as P router), undertakes the task of forwarding all data packets in the backbone network; the VPN users of each site pass through the user border router The CE is connected to the PE of the local operator's border router, and corresponds to a specific storage virtual router VRF on the PE. Some policies are configured on the VRF to specify the routing information of which sites the router of this site can receive and which routing information can be advertised to the outside. Each PE performs routing calculation according to the extended information of BGP (Border Gateway Protocol), and generates a routing table for each related VPN. The carrier border router PE equipment maintains multiple routing tables and supports multiple instances of dynamic routing protocols.

The carrier network is a public network used to transmit multicast data packets from different sites. It includes a public network multicast group (referred to as P-Group) and a public network multicast distribution tree (abbreviated as P-Tree).

The user's private network is an independent and autonomous IPv4 network system. It includes a private network multicast group (C-Group for short), and a private network multicast distribution tree (C-Tree for short).

Multicast VPN can be implemented in various forms. For example, the unicast solution (GRE Tunnel for short) is to establish a multicast full connection relationship between all CEs in the user VPN network to complete point-to-point tunnel connections. This solution has a serious efficiency problem. Every time one of the CEs is changed, all other CEs need to be reconfigured, so the expansion performance of the system is very poor.

The multicast domain solution (Multicast-Domain, MD for short) is realized by establishing and maintaining a multicast domain for each VPN in the existing operator network. It is essentially a multi-port tunnel, each PE router is a port of this tunnel, and the data entering from any port will flow out on other ports other than this port, so users can simply regard this multicast domain as It is a network switch (LAN Switch). In this solution, the multicast data is transmitted in the way of flooding in the multicast domain routers of the backbone network. The data forwarding is not optimal, and it will reach the router without private network receivers, and then be discarded. This is to a certain extent The network bandwidth in the backbone network is wasted, and the processing load of the router is also increased.

The multicast domain (MD) improvement scheme, when the data transmission volume of a certain multicast group of a certain VPN in the multicast domain exceeds a certain threshold, the VPN-IP PIM scheme will establish a dynamic multicast group for the multicast group Multicast Distribution Tree (MDT for short), multicast traffic can flow along this dynamic MDT optimization path. This can not only reduce the burden on operators to manage multicast routes in the public network, but also provide guarantee for high-speed multicast data transmission. In fact, this scheme of establishing dynamic MDT for VPN still has certain limitations, because there are many VPNs that need to be supported in the operational network, and there are many dynamic MDTs in each VPN, so the improved multicast In the domain method, there are still many multicast routing entries in the public network; at the same time, in this solution, only the large traffic in the public network multicast group can be detected, but the shortcomings caused by the sparse distribution of sites cannot be well handled .

In the existing VPN multicast scheme, the improved multicast domain scheme adopts traffic detection, its routing table items are completely controllable, and at the same time, it can optimize transmission for specific data sources, which has won the favor of most researchers. recognized. However, the improved multicast domain scheme only considers the problem of high sending rate of a certain source, but does not consider the problem of sparse station distribution, and the waste of bandwidth at this time is still very large.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for realizing VPN multicast in the multicast domain in view of the deficiencies in the prior art. This method takes into account the sparse distribution of receiving members, and introduces coverage The concept of detection determines the P-Tree according to the size of the coverage, which reduces the waste of bandwidth.

For this reason, the present invention provides a kind of method that realizes VPN multicast in multicast domain, comprises the steps:

Step 11, the group management router in the VPN network side periodically sends a coverage query message in the multicast domain for querying the current recipient PEs list;

Step 12, the router receiving the query message in the VPN determines the group management router that sends the query message;

Step 13, the router that receives the query message judges the type of the query message, if it is to query all groups, then perform step 14; if it is to query some groups, then perform step 17;

Step 14, the router that receives the query message sends all the multicast group addresses managed by the group management router in its routing forwarding table back to the group management router;

Step 15, the group management router collects the response message, and obtains the receiving member list of the queried group through statistics;

Step 16, the group management router analyzes the statistical results, calculates the current coverage of each group, according to the following formula:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{Tree})$

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{tree})$

Among them, PEs is the operator's border router, C-Group is the private network multicast group, and P-Tree is the public network multicast distribution tree; then perform step 2;

Step 17, the router that receives the query message confirms the group to be queried, if it is connected to a receiving member of the group, the group address is sent back to the group management router; then step 15 is performed;

Step 2, the VPN network side judges whether the value of the coverage is less than the preset coverage threshold, if yes, then execute step 3; if not, then end;

Step 3: A public network multicast distribution tree is established on the VPN network side, and the coverage of the public network multicast distribution tree by receiving members in the current multicast group is greater than or equal to a preset coverage threshold.

Aiming at the improved MD scheme, the present invention proposes a new concept of coverage. Through the detection of coverage, the waste of bandwidth caused by the sparse distribution of receiving member sites in the prior art is reduced. When the coverage does not meet the conditions In this case, by selecting or creating a P-Tree method to meet the coverage requirements, the sparse distribution of receiving member sites is avoided, and the waste of bandwidth is reduced.

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the flowchart of the first embodiment of the present invention;

Fig. 2 is the specific flowchart of step 1 in the first embodiment of the present invention;

Fig. 3 is the specific flowchart of step 3 in the first embodiment of the present invention;

Fig. 4 is a flowchart of a preferred embodiment of the present invention.

Detailed ways

Firstly, the relevant terms involved in the present invention will be introduced below.

Group management router: a router for management and maintenance and for mapping functions. The group management router is relative to each C-Group. For example, to switch to a private network multicast group (C-Group) in the public network, a public network multicast distribution tree (P-Tree) needs to be selected as its distribution tree. The group management router supervises and manages the C-Group, establishes a distribution tree P-Tree for it, and notifies other recipients of the C-Group, the operator's border router PE, to switch to the P-Tree. A router entity may contain many group management routers, and these group management routers can share the router's distribution tree, or apply to the router to create a new distribution tree. We also use group-managed router to denote a router entity that contains group-managed routers. In practice, the group management router can be undertaken by other functional entities, for example, PE routers.

Coverage: It means that when the receiver PE members of the private network multicast group (C-Group) are all PE members of the P-Tree (that is to say, the two are the relationship between the subset and the original set), the C-Group The degree of coverage of the P-Tree. Its value is a real value between [0, 1]. If a certain P-Tree is used to distribute the data packets of the C-Group, the smaller the coverage, the greater the bandwidth waste. Its formula is as follows:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{Tree})$

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{tree})$

Among them, PEs is the border router of the operator; C-Group is the private network multicast group; P-Tree is the public network multicast distribution tree.

Multicast domain: a distribution tree configured for each VPN, it is a static shared tree, including all PE members of the VPN, all C-Groups use this tree to distribute data by default, some VPN control Messages are also distributed in this tree.

Example 1

Fig. 1 is a flow chart of the first embodiment of the present invention. As shown in Figure 1, the present invention comprises the following steps:

Step 1, the group management router in the VPN network side periodically inquires about the current receiver PEs list, and the VPN network side calculates the coverage of receiving members in the current multicast group according to the following formula:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{Tree})$

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{tree})$

Among them, PEs is the border router of the operator; C-Group is the private network multicast group; P-Tree is the public network multicast distribution tree;

Step 2, the VPN network side judges whether the value of the coverage is less than the preset coverage threshold, if yes, then execute step 3; if not, then end;

Step 3: A public network multicast distribution tree is established on the VPN network side, and the coverage of the public network multicast distribution tree by receiving members in the current multicast group is greater than or equal to a preset coverage threshold.

Step 3 is to select an existing public network multicast distribution tree that can cover all receiving members of the current multicast group, and the coverage of all receiving members of the current multicast group for the distribution tree of the public network multicast group is greater than or equal to coverage degree threshold, or create a public network multicast distribution tree that can cover all receiving members of the current multicast group for all receiving members of the current multicast group, and all receiving members of the current multicast group are for the new public network multicast group The coverage of the distribution tree is greater than or equal to the coverage threshold.

Example 2

Fig. 2 is a specific flowchart of step 1 in the first embodiment of the present invention. The difference between this embodiment and embodiment 1 is that step 1 in embodiment 1 is specifically refined, and other steps are the same as embodiment 1. As shown in Figure 2, step 1 is specifically:

Step 11, the group management router in the VPN network side periodically sends a coverage query message in the multicast domain for querying the current recipient PEs list;

Step 12, the router receiving the query message in the VPN determines the group management router that sends the query message;

Step 13, the router that receives the query message judges the type of the query message, if it is to query all groups, then perform step 14; if it is to query some groups, then perform step 17;

Step 14, the router that receives the query message sends all the multicast group addresses managed by the group management router in its routing forwarding table back to the group management router;

Step 15, the group management router collects the response message, and obtains the receiving member list of the queried group through statistics;

Step 16, the group management router analyzes the statistical results, calculates the current coverage of each group, according to the following formula:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{Tree})$

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{tree})$

Among them, PEs is the operator's border router, C-Group is the private network multicast group, P-Tree is the public network multicast distribution tree; then end;

Step 17. The router receiving the query message confirms the group to be queried, and if it is connected to a receiving member of the group, sends the group address back to the group management router; and then executes step 15.

Example 3

Fig. 3 is a specific flowchart of step 3 in the first embodiment of the present invention. The difference between this embodiment and embodiment 1 is that step 3 is specifically refined, as shown in Figure 3, the specific steps of step 3 are:

Step 31: In the existing P-Tree on the VPN network side, whether there is a P-Tree that can cover the receiving members of the current multicast group, and the coverage of the receiving members in the current multicast group for the P-Tree is greater than or equal to Coverage threshold, if yes, then execute step 32; if no, then execute step 33;

Step 32, select an existing P-Tree to distribute information, and the coverage of the P-Tree of the receiving members of the current multicast group is greater than or equal to the coverage threshold; then end;

Step 33, create a new P-Tree that can cover all receiving members of the current multicast group for all receiving members in the current multicast group, and the coverage of all receiving members of the current multicast group for the new P-Tree is greater than or equal to the coverage threshold.

Example 4

Fig. 4 is a flowchart of a preferred embodiment of the present invention. As shown in Figure 4, the present invention comprises the following steps:

Step 11, the group management router in the VPN network side periodically sends a coverage query message in the multicast domain for querying the current recipient PEs list;

Step 12, the router receiving the query message in the VPN determines the group management router that sends the query message;

Step 13, the router that receives the query message judges the type of the query message, if it is to query all groups, then perform step 14; if it is to query some groups, then perform step 17;

Step 14, the router that receives the query message sends all the multicast group addresses managed by the group management router in its routing forwarding table back to the group management router;

Step 15, the group management router collects the response message, and obtains the receiving member list of the queried group through statistics;

Step 16, the group management router analyzes the statistical results, calculates the current coverage of each group, according to the following formula:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{tree})$

Among them, PEs is the operator's border router, C-Group is the private network multicast group, P-Tree is the public network multicast distribution tree; then end;

Step 17. The router that receives the query message confirms the group to be queried. If it is connected to a receiving member of the group, the group address is sent back to the group management router, and then step 15 is performed;

Step 2, the VPN network side judges whether the coverage is less than the preset coverage threshold, if yes, then execute step 3; if not, then end;

Step 31: In the existing P-Tree on the VPN network side, whether there is a P-Tree that can cover the receiving members of the current multicast group, and the coverage of the receiving members in the current multicast group for the P-Tree is greater than or equal to Coverage threshold, if yes, then execute step 32; if no, then execute step 33;

Step 32, select an existing P-Tree to distribute information, and the coverage of the P-Tree of the receiving members of the current multicast group is greater than or equal to the coverage threshold; then end;

Step 33, create a new P-Tree that can cover all receiving members of the current multicast group for the receiving members in the current multicast group, and the coverage of all receiving members of the current multicast group for the new P-Tree is greater than or equal to coverage degree threshold.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be The scheme shall be modified or equivalently replaced without departing from the spirit and scope of the technical scheme of the present invention.

Claims (3)

1. a method that realizes the VPN multicast in multicast domain is characterized in that, comprises the steps:

Group management router in step 11, the VPN network side periodically sends the coverage query messages in multicast domain, be used to inquire about current recipient PEs tabulation;

Receive among step 12, the VPN that the router of query messages determines to send described group of management router of described query messages;

Step 13, receive that the router of query messages judges the type of described query messages, if inquire about all groups, then execution in step 14; If the query portion group, then execution in step 17;

Step 14, the router of receiving query messages all are sent back to described group of management router to the multicast group address that belongs to described group of management router management in its route forwarding table;

Step 15, described group of management router are collected described response message, draw the reception member tabulation of the group of being inquired about through statistics;

Step 16, described group of management router analytic statistics result calculate the coverage of current each group, according to following formula:

$\mathrm{PEs}(C-\mathrm{Group})\⊆(P-\mathrm{Tree})$

Wherein, PEs is the operator edge router, and C-Group is the private network multicast group, and P-Tree is a public network multicast issuing tree; Execution in step 2 then;

Step 17, the router of receiving query messages are confirmed the group that will inquire about if oneself be connected with the reception member of this group, then this group address to be sent back to described group of management router; Execution in step 15 then;

Step 2, VPN network side judge that whether the numerical value of this coverage is less than predefined coverage threshold value, if then execution in step 3; If not, then finish;

Step 3, VPN network side are set up a public network multicast issuing tree, and receive in the current multicast group member for the coverage of described public network multicast issuing tree more than or equal to predefined coverage threshold value.

2. the method that in multicast domain, realizes the VPN multicast according to claim 1, it is characterized in that, all receive members' public network multicast issuing tree to described step 3 in order to select for use an existing energy to cover current multicast group, and described current multicast group all receive members for the coverage of this public network multicast group distribution tree more than or equal to the coverage threshold value, perhaps all receive newly-built one of members and can cover current multicast group all receive members' public network multicast issuing tree for current multicast group, and described current multicast group all receive members for the coverage of newly-built public network multicast group distribution tree more than or equal to the coverage threshold value.

3. the method that realizes the VPN multicast in multicast domain according to claim 1 is characterized in that described step 3 is specially:

Among step 31, the existing P-Tree of VPN network side, whether the P-Tree that can cover the described reception of current multicast group member is arranged, and receive in the described current multicast group member for the coverage of this P-Tree more than or equal to the coverage threshold value, if then execution in step 32; If not, execution in step 33 then;

Step 32, select an existing P-Tree distributing information, and the described reception of current multicast group member for the coverage of this P-Tree more than or equal to the coverage threshold value; Finish then;

Step 33, can cover current multicast group all receive members' P-Tree for receiving newly-built one of member described in the current multicast group, and described current multicast group all receive members for the coverage of newly-built P-Tree more than or equal to the coverage threshold value.

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