CN100433731C - Method for realizing VPN multicast - Google Patents

Abstract

The invention relates to a public network multicast issuing tree matching method, comprising: group management router calculates each covering degree value of the current private network multicast group in each existing public network multicast issuing tree; judging whether there is a public network multicast issuing tree whose covering degree value is greater than covering degree threshold: if yes, judging whether there is a unique issuing tree with the maximum covering degree: if yes, selecting the public network multicast issuing tree; if not, judging whether there is a unique static issuing tree: if yes, selecting the static issuing tree; if not, judging whether there is a unique most-quoted issuing tree: if yes, selecting the issuing tree; if not, selecting the earliest built public network multicast issuing tree. And it also relates to a VPN multicast implementing method, selecting matched tree or newly building a tree. And it reduces bandwidth waste.

Description

A kind of method that realizes the VPN multicast

Technical field

The present invention relates to a kind of public network multicast issuing tree matching method, the invention still further relates to a kind of method of the VPN of realization multicast.Belong to the communications field.

Background technology

In the network, each user access point is called a website (Site).Comprise following entity in VPN (Virtual Private Network) network: operator edge router (Provider Edge Router, be called for short PE) be used for providing network interface, storing virtual route (VirtualRouting Forwarding Instance for the user in provider backbone, be called for short VRF) transmit, handle the VPN-IPv4 route, insert the VPN subnet that is positioned at each website, be the main realization part of VPN; User's border router (Customer Edge Router, be called for short CE), the network interface of access carrier backbone network in the user VPN website converges the VPN route of this website, issue and receive the user network route; Carrier network core router (being called for short the P router) is being born the task that all packets are transmitted in backbone network; The VPN user of each website connects local operator edge router PE through user's border router CE, and on PE the virtual route VRF of corresponding specific memory.Last some strategies of configuration of VRF stipulate that the router of this website can receive the routing iinformation of which website, can outwards issue those routing iinformations.Each PE carries out route according to the extend information of BGP (Border Gateway Protocol) and calculates, and generates the routing table of each relevant VPN.The a plurality of routing tables of operator edge router PE plant maintenance, many examples of support dynamic routing protocol.

Carrier network is the public network network that is used to transmit the multicast packet of different websites.Wherein, comprise public network multicast group (being called for short P-Group), public network multicast issuing tree (being called for short P-Tree).

User's private network be one independently, autonomous IPv4 network system.Wherein, comprise private network multicast group (being called for short C-Group), private network multicast distribution tree (being called for short C-Tree).

Multicasting VPN scheme in a variety of forms realizes that as unicast scheme, this scheme exists serious efficiency, one of them CE of every change, and other are all all needs to reconfigure, so the scalability of system is very poor.Multicast domain scheme (Multicast-Domain, be called for short MD), multicast packet adopts the mode of inundation to transmit in backbone network multicast domain router, data forwarding is not optimum the forwarding, can arrive the router that does not have the private network recipient, be dropped then, this has wasted the network bandwidth in the backbone network to a certain extent, has also increased the processing load of router.

More excellent scheme is multicast domain (MD) improvement project at present, when certain the multicast group data transmission quantity of certain VPN in the multicast domain surpasses certain threshold value, adopt VPN-IP PIM scheme to set up a dynamic MDT (Multicast Distribution Tree for this multicast group, multicast distribution tree), flux of multicast can be optimized path flow along this dynamic MDT.Can reduce like this multicast path in the operator management public network by burden, also provide guarantee simultaneously for muticast data transmission at a high speed.In fact, this scheme of setting up dynamic MDT for VPN still exists certain limitation, because in operation, need in the network VPN number supported a lot, and a lot of dynamically MDT arranged again among each VPN, thus when adopting improved multicast domain method in the public network multicast routing table item still a lot; Simultaneously, in the middle of this scheme, can only detect the big situation of flow in the public network multicast group, can not good treatment and website is distributed the sparse shortcoming that causes.

Improved multicast domain scheme is controlled fully with its route table items, and the advantage that can be optimized transmission simultaneously again at specific data source has obtained the approval of most researchers.But improved multicast domain scheme has only been considered the high problem of certain source transmission rate, and does not consider the sparse problem of website distribution, and bandwidth waste at this moment still is very large.

Summary of the invention

Technical problem to be solved by this invention is at deficiency of the prior art, calculate by coverage, the method of utilizing existing public network multicast issuing tree to mate, reduced the waste of the network bandwidth in the public network, reduce the multicast tree amount of information that router is safeguarded in the public network simultaneously, when reducing the server burden, made network can support more Virtual Private Network multicast service.

For this reason, the invention provides a kind of public network multicast issuing tree matching method, comprise the steps:

Step 1, group management router are calculated current private network multicast group each coverage numerical value in each existing public network multicast issuing tree according to following coverage formula,

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

Wherein, PEs is the operator edge router, C-Group is the private network multicast group, P-Tree is a public network multicast issuing tree, coverage is meant that the private network multicast group is to the level of coverage of public network multicast issuing tree when recipient's operator edge router member of private network multicast group is the operator edge router member of public network multicast issuing tree;

Step 2, group management router judge whether there be the public network multicast issuing tree of coverage numerical value greater than predefined coverage threshold value in the described public network multicast issuing tree, if then execution in step 3; If not, then it fails to match, finishes then;

Step 3, group management router judge whether to exist the public network multicast issuing tree of a unique coverage maximum in the public network multicast issuing tree greater than described coverage threshold value, if then the public network multicast issuing tree coupling with this coverage maximum is the distribution tree of this private network multicast group; If not, execution in step 4 then;

Step 4, group management router judge whether to exist the public network multicast issuing tree of unique static state in the public network multicast issuing tree greater than described coverage threshold value, if public network multicast issuing tree coupling that then should static state is the distribution tree of this private network multicast group; If not, execution in step 5 then;

Step 5, group management router judge whether to exist a unique maximum public network multicast issuing tree of being quoted by each private network multicast group of quantity, if then this public network multicast issuing tree coupling is the distribution tree of this private network multicast group; If not, execution in step 6 then;

Step 6, be the distribution tree of this private network multicast group with creation-time public network multicast issuing tree coupling the earliest.

The present invention also provides a kind of method of the VPN of realization multicast, comprises the steps:

Step 1, group management router are according to the private network multicast group signal that changes the carrying tree state, in existing public network multicast issuing tree, judge whether to exist one can cover current private network multicast group, and the public network multicast issuing tree of selecting according to described public network multicast issuing tree matching method that is complementary with this private network multicast group; If then execution in step 3; If not, execution in step 2 then;

Step 2, set up a new public network multicast issuing tree, finish then for this private network multicast group;

Step 3, select this public network multicast issuing tree to be the distribution tree of this private network multicast group.

The present invention calculates by coverage, and the method for utilizing existing public network multicast issuing tree to mate has reduced the multicast routing table amount of information of safeguarding in the public network; The present invention uses public network multicast issuing tree matching method again, set up one and meet the distribution tree that coverage requires, reduced the sparse bandwidth waste that causes of butt joint harvest person website distribution in the prior art, under the situation that coverage does not satisfy condition, by the method for a selection or a newly-built P-Tree, the feasible requirement of satisfying coverage has just avoided receiving the sparse situation of member's website distribution, reduce the waste of bandwidth, reduced the amount of information that multicast routing table is safeguarded in the public network simultaneously.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Fig. 1 is the flow chart of first embodiment of the invention;

Fig. 2 is the flow chart of second embodiment of the invention.

Embodiment

At first introduce relational language involved in the present invention below.

Group management router: for managing with maintenance work and being used to finish the router of mapping function.The group management router is with respect to each C-Group.As, switch to the private network multicast group (C-Group) in the public network, need select the distribution tree of a public network multicast issuing tree (P-Tree) for it as it.The group management router is exactly supervision and management C-Group, and for it sets up distribution tree P-Tree, and other recipient's operator edge router PE of notice C-Group switches on this P-Tree.A router entity may comprise a lot of group management router, and these group management router can be shared the distribution tree of this router, perhaps to the newly-built distribution tree of this router solicitation.We also represent that with the group management router comprises a router entity of organizing management router.

Coverage: be meant that C-Group is to the level of coverage of P-Tree when recipient PE member when private network multicast group (C-Group) is the PE member of P-Tree (that is to say that both are relations of subclass and former collection).Its value is a real number value between [0,1].If adopt certain P-Tree to distribute the packet of this C-Group, coverage is more little, represents that then the bandwidth waste degree is big more.Its formula is as follows:

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

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.

Multicast domain: be one the distribution tree that each VPN disposed, it is a static shared tree, has comprised all PE members of VPN, and all C-Group acquiescences are used this tree distributing data, and the control messages of some VPN is also distributed in this tree.

Switch: when the packet in the private network transmits in public network, we need select a P-Tree as distribution tree to it, and in order to optimize transmission, the public network distribution tree that is adopted also is dynamic change, and we select this process of distribution tree to be called " switching " process.Precondition according to the difference of distribution tree type and switching is different, switches also to be divided into polytype.

Tree type involved in the present invention is as follows:

Public network multicast issuing tree (P-Tree) adopts the source tree type.When private network multicast group (C-Group) is the source tree, should adopt the P-Tree distributing data of source tree type; When C-Group is a shared tree, but comprise a RP (Rendezvous Point, convergent point) point in the website, and data source is that unicast packet arrives the RP point, the packet of this group also can adopt the P-Tree of source tree type when passing through public network, to realize optimum the forwarding.

Public network multicast issuing tree (P-Tree) adopts the shared tree type.Private network multicast group (C-Group) should adopt the P-Tree of shared tree type when being shared tree.

Public network multicast issuing tree (P-Tree) can also be divided into two kinds of static tree and dynamic trees.

Static tree P-Tree is set up by manual configuration.Every in public network the stable distribution tree of topology can adopt the mode of static configuration, and any static tree can not be routed device deletion automatically.For example, all multicast domains must adopt static tree to realize, and also should be configured to the static multicast tree for the medium-term and long-term P-Tree that occurs of public network, so that stablize P-Tree route entry in the public network, reduce maintenance costs, accelerate repeating process.

In order to reduce the amount of information of the routing table in the public network, just must support dynamic tree P-Tree.These P-Tree have only when needed and just can be established, and can exist when having C-Group to quote always, and when its reference count was zero, the group management router just can initiatively discharge this dynamic tree, to reduce the multicast route entry of safeguarding in the public network.The quantity of the dynamic tree that can set up should be controlled by operator by certain mode, has good extensibility to guarantee carrier network.

Pe router for safeguard its mapping relations of the P-Tree that sets up and C-Group and P-Tree, need maintenance tree table and group table to manage these essential informations.Tree table involved in the present invention is as follows with the group table:

The tree table has been preserved the P-Tree information that the group management router is set up, and is the main foundation of selecting the public network forwarding tree for C-Group.The data item that table 1 is comprised for the tree table, as shown in table 1:

Table 1

IP Address

Tree Label

Tree-Type

Ref-Count

Dynamic

PEs-List

In the table 1,

The IPv4 multicast address of IP Address:P-Tree, i.e. P-Group;

The mark of Tree Label:P-Tree;

The type of Tree-Type:P-Tree, source tree or shared tree;

Ref-Count: the C-Group number of quoting this tree;

Dynamic: the dynamic mark of setting up, whether identify this P-Tree is dynamically to set up;

PEs-List:PE member's tabulation, the sign PE member that P-Tree covered.

The information about firms that switches to the C-Group on the P-Tree that table 2 is preserved for the group table, as shown in table 2:

Table 2

VPN-RD

G

PEs-List

In the table 2,

VPN-RD: identify the affiliated VPN of this group;

G: private network multicast address;

PEs-List:PE member's tabulation identifies the PE member that this group covers.

C-Group in the group table is that those meet switching condition, leaves the multicast domain distribution tree of acquiescence, is optimized the C-Group of transmission in public network.In order to represent that switching has taken place this group, and safeguard the information of this group in public network, need the group management router periodically to send corresponding M DTJoin TLV (switching message) message, notify other recipient PE to transmit on the corresponding P-Tree of this C-Group outside multicast domain to multicast domain.

Another alternative plan is: if can tolerate the delay of Join (adding multicast group) process, and just can maintenance group table.When the member who obtains C-Group when needs tabulates, know that by interim transmission member PE query messages this organizes all member PEs.

Defconstant involved in the present invention is as follows:

Flow threshold:, need two borders up and down of definition flow threshold for the frequent switching phenomenon that prevents from the border, to take place.In the flow detection process, when the high outflow of the flow upper bound of certain C-Group, it will be switched in the middle of the public network, and when its flow was lower than the flow lower bound, it can be switched back in the middle of the multicast domain again.And between the flow lower bound and the upper bound, have one section dead band, when flow value was positioned at this zone, C-Group kept original state constant.The length of controlling this dead band can be controlled the degree of stability of public network multicast group.

Embodiment 1

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

Step 1, group management router are calculated current private network multicast group each coverage numerical value in each existing public network multicast issuing tree according to following coverage 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;

Step 2, group management router judge whether there be the public network multicast issuing tree of coverage numerical value greater than predefined coverage threshold value in the described public network multicast issuing tree, if then execution in step 3; If not, then it fails to match, finishes then;

Step 3, group management router judge whether to exist the public network multicast issuing tree of a unique coverage maximum in the public network multicast issuing tree greater than described coverage threshold value, if then execution in step 7; If not, execution in step 4 then;

Step 4, group management router judge whether to exist the public network multicast issuing tree of unique static state in the public network multicast issuing tree greater than described coverage threshold value, if then execution in step 8; If not, execution in step 5 then;

Step 5, group management router judge whether to exist a unique maximum public network multicast issuing tree of being quoted by each private network multicast group of quantity, if then execution in step 9; If not, execution in step 6 then;

Step 6, will select creation-time public network multicast issuing tree coupling the earliest to be the distribution tree of this private network multicast group;

Step 7, the public network multicast issuing tree of this coverage maximum coupling be the distribution tree of this private network multicast group, end then;

Step 8, public network multicast issuing tree coupling that should static state are the distribution tree of this private network multicast group, end then;

Step 9, this public network multicast issuing tree coupling is the distribution tree of this private network multicast group, end then.

Above step concrete operations are as follows:

Suppose and to comprise the member { the group R of PE8} distributes one tree for PE1, PE4, and following table 11 tabulations are the tree table for one.

Wherein coverage calculates.

Table 11

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
												1	√	√	√	×	√	×	×	√	Static	13	-

2	√	√	×	√	×	×	√	√	Static	12	0.6
												3	×	√	√	√	×	×	√	√	Static	9	-
4	√	×	×	√	√	×	×	√	Static	16	0.75
												5	√	√	×	√	×	×	×	√	Static	16	0.75
6	×	√	√	√	√	√	√	×	Static	12	-
												7	√	×	√	√	×	√	×	√	Static	8	0.6
8	√	√	√	×	×	√	×	√	Static	11	-
												9	√	×	√	√	√	×	√	√	Dynamically	3	0.5
10	√	√	×	√	×	√	√	×	Dynamically	6	-
												11	×	√	√	×	×	×	×	×	Dynamically	2	-
12	√	×	√	√	×	×	×	√	Dynamically	1	0.75
												13	×	√	×	√	×	×	√	√	Dynamically	1	-
14	×	×	×	×	×	×	√	×	Dynamically	3	-
												15	√	√	×	√	√	×	×	√	Dynamically	1	0.6
16	√	√	×	√	√	×	√	√	Dynamically	2	0.5
												17	×	√	×	√	√	×	×	√	Dynamically	1	-
18	√	×	×	√	×	√	×	×	Dynamically	1	-
												19	×	×	√	×	×	×	×	×	Dynamically	1	-

Step 101, suppose that we are decided to be 0.6 with the coverage threshold value, then we can see that to satisfy the tree that coverage requires as shown in table 12, for:

Table 12

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
													2	√	√	×	√	×	×	√	√	Static	12	0.6
4	√	×	×	√	√	×	×	√	Static	16	0.75
												5	√	√	×	√	×	×	×	√	Static	16	0.75
7	√	×	√	√	×	√	×	√	Static	8	0.6
												12	√	×	√	√	×	×	×	√	Dynamically	1	0.75
15	√	√	×	√	√	×	×	√	Dynamically	1	0.6

Step 102, choose the tree of a unique coverage maximum again, the result is as shown in table 13:

Table 13

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
													4	√	×	×	√	√	×	×	√	Static	16	0.75
5	√	√	×	√	×	×	×	√	Static	16	0.75
												12	√	×	√	√	×	×	×	√	Dynamically	1	0.75

Do not obtain unique tree in step 103, the step 102, then choose static tree, the result is as shown in table 14:

Table 14

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
													4	√	×	×	√	√	×	×	√	Static	16	0.75
5	√	√	×	√	×	×	×	√	Static	16	0.75

Step 104, step 103 do not obtain unique tree yet, then choose the maximum tree of number of references.As shown in table 15, and because two tree number of references selecting now are identical, so the result does not change:

Table 15

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
													4	√	×	×	√	√	×	×	√	Static	16	0.75
5	√	√	×	√	×	×	×	√	Static	16	0.75

Do not obtain unique tree in step 105, the step 104 yet, then choose creation-time tree the earliest, as shown in table 16, the time the earliest at first, the result is as follows:

Table 16

Sequence number	PE1	PE2	PE3	PE4	PE5	PE6	PE7	PE8	The tree type	Number of references	Coverage
													4	√	×	×	√	√	×	×	√	Static	16	0.75

Through above step, can select sequence number and be 4 the unique tree of result, should set coupling and give group R, number of references adds one, and revises the out of Memory of safeguarding in tree table and the group table, once selects to set and assigning process can be finished.

Embodiment 2

Fig. 2 is the flow chart of second embodiment of the invention.Embodiment 2 is a kind of side that realizes the VPN multicast

Method comprises the steps:

Step 11, group management router are according to the private network multicast group signal that changes the carrying tree state, in existing public network multicast issuing tree, judge whether to exist one can cover current private network multicast group, and the public network multicast issuing tree of selecting according to described public network multicast issuing tree matching method that is complementary with this private network multicast group; If then execution in step 13; If not, execution in step 12 then;

Step 12, set up a new public network multicast issuing tree, finish then for this private network multicast group;

Step 13, select this public network multicast issuing tree to be the distribution tree of this private network multicast group.

Saidly in the step 12 in the present embodiment setting up a new tree, is to set up a new public network multicast issuing tree separately at the member in the current private network multicast group.

Embodiment 3

The difference of present embodiment and embodiment 2 only is that the group management router in the step 11 receives the new user that the private network multicast group signal that changes the carrying tree state comes from the Add User multicast group or the existing multicast group of network side transmitted and adds message.

Embodiment 4

The difference of present embodiment and embodiment 2 only is that whether the private network multicast group signal of the change carrying tree state in the step 11 comes from numerical value that the group management router judges coverage less than the predefined first coverage threshold value, and whether flow number is less than the signal of preset flow rate threshold value.

Embodiment 5

The difference of present embodiment and embodiment 2 only is that the private network multicast group signal of the change carrying tree state in the step 11 comes from the group management router and whether judges coverage numerical value smaller or equal to the predefined second coverage threshold value, and whether flow number is more than or equal to the signal of preset flow rate threshold value.

It should be noted last that, above embodiment is only unrestricted in order to technical scheme of the present invention to be described, although the present invention is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, can make amendment or be equal to replacement technical scheme of the present invention, and not break away from the spirit and scope of technical solution of the present invention.

Claims (5)

1. a public network multicast issuing tree matching method is characterized in that, comprises the steps:

Step 1, group management router are calculated current private network multicast group each coverage numerical value in each existing public network multicast issuing tree according to following coverage formula,

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

Wherein, PEs is the operator edge router, C-Group is the private network multicast group, P-Tree is a public network multicast issuing tree, coverage is meant that the private network multicast group is to the level of coverage of public network multicast issuing tree when recipient's operator edge router member of private network multicast group is the operator edge router member of public network multicast issuing tree;

Step 2, group management router judge whether there be the public network multicast issuing tree of coverage numerical value greater than predefined coverage threshold value in the described public network multicast issuing tree, if then execution in step 3; If not, then it fails to match, finishes then;

Step 3, group management router judge whether to exist the public network multicast issuing tree of a unique coverage maximum in the public network multicast issuing tree greater than described coverage threshold value, if then the public network multicast issuing tree coupling with this coverage maximum is the distribution tree of this private network multicast group; If not, execution in step 4 then;

Step 4, group management router judge whether to exist the public network multicast issuing tree of unique static state in the public network multicast issuing tree greater than described coverage threshold value, if public network multicast issuing tree coupling that then should static state is the distribution tree of this private network multicast group; If not, execution in step 5 then;

Step 5, group management router judge whether to exist a unique maximum public network multicast issuing tree of being quoted by each private network multicast group of quantity, if then this public network multicast issuing tree coupling is the distribution tree of this private network multicast group; If not, execution in step 6 then;

Step 6, be the distribution tree of this private network multicast group with creation-time public network multicast issuing tree coupling the earliest.

2. an application rights requires 1 described public network multicast issuing tree matching method to realize the method for VPN multicast, it is characterized in that, comprises the steps:

Step 1, group management router are according to the private network multicast group signal that changes the carrying tree state, in existing public network multicast issuing tree, judge whether to exist one can cover current private network multicast group, and the public network multicast issuing tree of selecting according to described public network multicast issuing tree matching method that is complementary with this private network multicast group; If then execution in step 3; If not, execution in step 2 then;

Step 2, set up a new public network multicast issuing tree, finish then for this private network multicast group;

Step 3, select this public network multicast issuing tree to be the distribution tree of this private network multicast group.

3. the method for realization VPN multicast according to claim 2 is characterized in that, the new user that the private network multicast group signal of described change carrying tree state comes from the Add User multicast group or the existing multicast group of network side transmitted adds message.

4. the method for realization VPN multicast according to claim 2, it is characterized in that, whether the private network multicast group signal of change in the described step 1 carrying tree state comes from numerical value that the group management router judges coverage less than the predefined first coverage threshold value, and whether flow number is less than the signal of preset flow rate threshold value.

5. the method for realization VPN multicast according to claim 2, it is characterized in that, the private network multicast group signal of change in the described step 1 carrying tree state comes from the group management router and whether judges coverage numerical value smaller or equal to the predefined second coverage threshold value, and whether flow number is more than or equal to the signal of preset flow rate threshold value.

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