CN100396058C - IP group broadcasting method for supporting different service quality in specification service network domain - Google Patents

Abstract

The present invention belongs to the technical field of an internet, which is characterized in that one multicast tree administration module is arranged on each boundary router of a differentiated service network domain. The module is used for servicing one multicast tree aggregate. Different multicast groups are required to share a multicast tree. Thereby, the status information quantity of router maintenance is greatly decreased. Group members are divided into subgroups with the same service quality according to service quality requirements and respectively use different trees to receive multicast information. Thereby, influence cause by the different service quality requirements of the group members is solved. The method is used for requesting and looking for proper multicast trees for incoming group members on the boundary router of the network domain. A network domain core router is needed for supporting general multicast transmission and does not need maintaining the state of service quality. The realization of the method is simple. One multicast tree administration module is needed to add on each boundary router of a differentiated service network, and relating operation is completed by the module.

Description

The IP method of multicasting of supporting different service quality in specification service network domain

Technical field

The IP method of multicasting of supporting different service quality in specification service network domain belongs to Internet technical field.

Background technology

Along with the develop rapidly of multimedia application, Next Generation Internet requires to provide service quality (Quantity of Service is called for short QoS) to support and some IP multicast (Multicast) mechanism to multiple spot or multiple spot to multiple spot.But these two kinds of services all need the router maintenance of state information, bring scalability problem to router.

Provide the conventional method of service quality all will on router, write down the QoS state information of each transport stream on the internet.Along with online transport stream quantity increases, the number of states that needs to safeguard also increases, and the storage of router and processing expenditure increase, and this almost is the heavy burden that can not bear for the core router of backbone network.For this reason, people put forward a kind of new internet QoS architecture---Differentiated Services (DiffServ, referring to RFC2474, RFC2475 and RFC2638 etc.), it is placed on the preservation of transport stream state information and monitoring the border router of network domains, territory inner core router needn't safeguard that every circulation sends out state, only need stream aggregation is dispatched forwarding, be with good expansibility.Bandwidth broker in the different service domains (Bandwidth Broker is called for short BB) is responsible for safeguarding that the resource allocation of whole network domains and the new transmission of control flow to into the territory.Newly arrived stream at first will with the BB consulting service quality, just can enter territory transmission after being allowed to.The example of differentiated services network as shown in Figure 1.

The IP multicast be that the one or more senders of a kind of permission (being called multicast source) send to a plurality of recipients network technology of (be called and receive the member) simultaneously with packet, a data grouping only needs to send once.Multicast source sends to particular multicast group to packet, just can receive packet and only have the main frame that belongs to this multicast group address.Briefly, main frame is by using Internet igmpinternet (IGMP, see also RFC1112) add in certain multicast group, and can dynamically leave group, this variation relation of router trace also attempts to form a loop-free paths that arrives multicast member, and this path forms tree (as shown in Figure 2) on network topology.For convenience, the multicast of being carried below all refers to the IP multicast.

Multicast source and recipient are referred to as multicast member, and multicast supports the member relation dynamic change to be the adding of multicast member and to leave.Multicast transmission is compared (as shown in Figure 3) with clean culture (Unicast) transmission:

(1) unicast transmission needs independent data channel between sender and each recipient.If a main frame transmits data for simultaneously very a spot of recipient, generally there is not any problem.If but be difficult to realize when the same a copy that a large amount of main frames wish to obtain packet is arranged.This will cause the sender, and overburden, postpone long, network congestion.

(2) multicast transmission has improved data-transmission efficiency.Reduce backbone network and congested possibility occurred.Main frame in the multicast group can be at same physical network, also can be from different physical networks.

In brief, the multicast tree that the IP multicast utilizes router to form is transmitted multicast packet, and multicast source only sends the multicast conversation data one time, and packet is replicated transmission at the breakout of multicast tree.The advantage of multicast is the load pressure that has reduced multicast source and source link, has improved efficiency of transmission.

But, there is shortcoming in traditional IP multicast mechanism, be that each multicast conversation needs a multicast tree to transmit information, every multicast tree corresponding multicast forwarding list item on router, when multicast conversation concurrent on the network is a lot, forwarding state increases thereupon, and this can greatly increase the processing expenditure of router, the performance of reduction router.If realize traditional IP multicast scheme in supporting Differentiated Services, the state scalability problem becomes more serious, because except basic multicast forwarding state, router also will be each multicast group maintenance service quality state information.When having a lot of multicast group simultaneously in the network, therefore territory inner core router faces immense pressure.In addition, the member of same multicast group has different QoS requirements, and this complexity makes and influences each other between the contiguous group membership, increased multicast charging difficulty; Even for some service quality, its evaluation index difference, member on the same group can not receive on same multicast tree and satisfy the data of QoS requirement separately.

At present domestic and international research mechanism and personnel have proposed some solutions and international standard (as RFC3754) at the problem that realizes multicast transmission in the differentiated services network territory, but all there is limitation in these methods, can not be comprehensively, address this problem efficiently.

The method of multicasting of the supporting different service quality in specification service network domain that the present invention proposes has solved the problems referred to above that run into when multicast is supported service quality well.It is shared between different multicast group and uses multicast tree, and along with concurrent multicast group quantity increases, the quantity of the tree of safeguarding on the territory reduces greatly than the quantity of the tree that traditional multicast needs; It is divided into the identical child group of service quality with the group membership according to QoS requirement, uses different tree receiving group information respectively, thereby has solved the influence that group membership's QoS requirement difference is brought, and has realized the IP multicast of different service quality effectively; This method is suitable for Differentiated Services architecture characteristics, is that new multicast request is sought suitable multicast tree on the network domains border router, and the network domains core router only need be supported general multicast transmission, needn't safeguard the state about service quality.

The present invention is easy to dispose and realizes, only need increase a functional module TA (Tree Agent) on each border router of differentiated services network, and operating procedure is finished by the TA module.

Summary of the invention

The object of the present invention is to provide a kind of method of multicasting of supporting different service quality in specification service network domain, it has good forwarding state extensibility, and can effectively solve the different problem of group membership's QoS requirement.

Method proposed by the invention is characterised in that described method realizes that in the differentiated services network territory described differentiated services network territory comprises: a plurality of border routers, preserve state information with the monitoring transport stream; A plurality of territories inner core router is dispatched forwarding to stream aggregation, has extensibility; The bandwidth broker node in a described territory is represented with BB, and whether decision allows the new network flow that arrives to enter the territory to transmit according to the resource allocation conditions of entire domain; Each multicast group a source arranged, send multicast packet by a border router, a plurality of multicast members are arranged, receive data by corresponding border router; These multicast group are transmitted information by corresponding multicast tree on this different service domains, and the service quality that obtains separately guarantees;

In this differentiated services network territory, realize described method of the present invention according to following steps successively:

Step 1. is represented with TA at a multicast tree administration module of each border router deploy in differentiated services network territory, will be safeguarded following data message at least in this module:

Multicast tree set TS, every tree wherein all use tree address unique in the territory to identify, and these are set all is to be root with TA place router, support different levels of quality of service, but every tree is only supported a kind of levels of quality of service;

Group-tree address respective function

Its group address was replaced by the tree address when transport stream entered different service domains through border router, and group address will be replaced back in the tree address when leaving this territory, the corresponding one or more trees of a group address, and these trees have been born the task of transmitting this group information jointly;

The link loss assessment W (T) of multicast tree is in order to assess the link loss that causes owing to redundant leaf node waste bandwidth; Thereby in module TA, be defined as follows parameter at least:

c _e: constitute the link cost of the limit e of tree T, default value is 1

C (T): the link cost of tree T, the link cost sum on all limits of formation T

n _G: set the group quantity that T supports transmission

G _i: set i the group that T supports transmission

π _T(G _i): expression tree T is by multicast group G _iThat part of link that uses is the subclass of T, promptly ${\mathrm{\π}}_T\left(G_i\right)\⊆T$

W ₀: predetermined link loss threshold value, be one less than 1 nonnegative real number

W (T): the link loss assessment of tree T

Group-tree address respective function

TS: the multicast tree set, it is a global variable

TStemp: interim multicast tree set, it is a temporary variable

TA is provided with following computing formula at least:

The link cost of tree T: C (T)=∑ _{E ∈ T}c _e

G _iLink cost on T: C (π _T(G _i))=∑ _{E ∈ π T (Gi)}c _e

Tree T link loss assessment: $W\left(T\right)=\left[{\mathrm{\Σ}}_{i=1}^{n_G}C\left(T\right)\right]/\left[{\mathrm{\Σ}}_{i=1}^{n_G}C\left({\mathrm{\π}}_T\left(G_i\right)\right)\right]-1;$

When step 2. receives that as the interface I of border router multicast that main frame is sent joins request message, claim this moment this router to be the lower exit router of this multicast group in this territory, be designated as Reg, because it will be the outlet of multicast traffic stream leaving domain, this multicast message that joins request comprises the source address s and the requested service quality scale q of described multicast group address g, multicast at least, be designated as Join (s, g, q):

If the interface I of this egress router Reg is not at (s, g, in outgoing interface tabulation q), then module TA is packaged into unicast messages with Join message, be designated as TA_Join_Req (s, g, q), module TA it to source s direction clean culture, wait acknowledge message then, if this message adds successfully, then set up forwarding state, interface I is added in its outlet tabulation;

Step 3. is purpose unicast messages TA_Join_Req (s when border router receives with source s, g, q) time, claim that this router is the upstream ingress router of group g on this territory this moment, be designated as Ring, because it will be the inlet that multicast traffic stream enters the territory, its TA module is selected the tree process, at first put an interim multicast tree set TStemp for empty, carry out following steps then successively:

Step 3.1. is optional one tree t in multicast tree set TS successively, then forwards step 3.4 to if all selected;

Step 3.2. does not perhaps comprise outlet boundary node Reg if this tree t does not support levels of quality of service q in Shu the leaf node, forward step 3.1 to;

Step 3.3. calculates the link loss assessment W (t) of tree t, if W (t)＜W ₀, then will set t and join among the interim multicast tree collection TStemp; Otherwise, forward step 3.1 to;

Step 3.4. forwards step 4 to and carries out the achievement process, otherwise select one tree in TStemp if the interim multicast tree set TStemp of this moment is empty, is designated as t ₁, choice criteria is according to following priority orders:

A. link loss assessment minimum;

B. bear and transmit the multicast conversation minimum number;

C. select one at random;

Step 3.5. is consulted by module TA and described bandwidth broker Node B B, tree t ₁Whether can support this new multicast to add demand from lower exit router Reg:

If obtain permission, then egress router Reg sends adding successful respond message downstream, notifies it to transmit tree and is t ₁And the tree address, forward step 5 to and wait for forwarding;

Otherwise, with t ₁From interim multicast tree set TStemp, delete, forward step 3.4 to;

Step 4. is initiated to carry out the achievement process by upstream ingress router Ring, and execution in step is as follows:

Whether the module TA of this router of step 4.1. and BB negotiation allow to set up the path from Ring to Reg,

If be not allowed to, illustrate that current network resources is not enough to support the multicast request of Reg, then egress router Reg sends adding failure response message downstream, notifies it to join request and is rejected, and step 4 finishes;

If obtain allowing, remember that this paths is t _New, with t _NewThe multicast tree that is added to the TA maintenance of Ring is gathered among the TS;

If step 4.2. is t _NewBe the tree of unique support transmission group, for it distributes new tree address; Otherwise, have other one tree t among the multicast tree set TS _OldSupport that also (q), can consideration merge t to the transmission group for s, g _OldAnd t _New, calculate W (t _Old+ t _New):

If step 4.2.1. is less than W ₀Then merge, use t _OldTree address designation t _NewOtherwise, be t _NewDistribute new tree address;

Step 4.3. module TA notifies t _NewOn the territory on router set up corresponding multicast forwarding list item, this forwarding-table item comprises the incoming interface and the outgoing interface tabulation of address, the multicast packet of this tree at least;

Step 4.4. module TA egress router Reg downstream sends adding successful respond message, notifies it to transmit tree and is t _NewAnd appropriate address;

When step 5. is received the multicast information of group g of source s as upstream ingress router Ring, carry out repeating process:

Step 5.1.Ring is converted to corresponding tree address with the group address of this multicast data packet;

Territory inner core router on the step 5.2. tree is transmitted this multicast information according to this tree address;

After step 5.3. lower exit router Reg receives multicast information, original group address is replaced back in the tree address, pass from outlet;

When step 6. was received the multicast leave group message that main frame sends as the interface I of border router, this router was the lower exit router, and this message comprises group address g, source address s and requested service quality scale q at least, be designated as Leave (s, g, q), carry out following steps:

The module TA of this border router of step 6.1. deletes interface I from forwarding-table item;

This module of step 6.2. TA with Leave message be packaged into TA_Leave (s, g, q), it to source s direction clean culture;

Step 7. when border router receive unicast messages TA_Leave (s, g is in the time of q), this router and source s are connected to the upstream ingress router, its module TA finds corresponding tree t ' in multicast tree set TS, calculate the link loss assessment W (t ') of tree t ', if W (t ') 〉=W ₀, carry out tree according to following steps and adjust operation:

(q), then directly deletion comprises the branch of lower exit router Reg to step 7.1. for s, g, and notifies the core router in this branch to revise the multicast forwarding list item if tree t ' only supports to transmit multicast group;

Otherwise, tree t ' also supports to transmit other multicast group, the all-router except arrive lower exit router Reg branch of tree on the t ' constituted a new tree t, and the forwarding status information of "; distribute new tree address, and notify the router increase t in the branch of Reg " keeps the state information of t ' simultaneously;

The module TA notice BB of this router of step 7.2. Ring, multicast group (leave for s, g, discharges resource by lower exit router Reg branch q).

For above-mentioned steps, the handling process of step 2 as shown in figure 11, the handling process of step 3 and step 4 as shown in figure 13, the handling process of step 7 as shown in figure 12.

Can prove the multicast tree shared mechanism that this invention is used by simulated experiment, can solve the state scalability problem of traditional multicast well, along with concurrent multicast group quantity increases, the quantity of the tree of safeguarding on the territory reduces greatly than the quantity of the tree that traditional multicast needs.

Description of drawings

Fig. 1. the differentiated services network exemplary plot:

ER is border router (Edge Router),

CR is territory inner core router (Core Router),

BB is bandwidth broker (Bandwidth Broker);

Fig. 2 .IP multicast exemplary plot:

Circle is represented router node,

The expression host node, wherein the expression of grey participates in the host node of multicast,

Straight line is represented the interconnecting relation between the node, and wherein thick line is represented multicast tree, and arrow represents that multicast packet flows to;

Fig. 3. multicast transmission and unicast transmission comparison diagram,

Circle is represented router node,

The expression host node,

Straight line is represented the interconnecting relation between the node,

Arrow is represented data flow;

Fig. 4. the method for multicasting exemplary plot of supporting different service quality in specification service network domain,

Circle is represented the border core router of different service domains,

Core router in the square representative domain,

Thin-line arrow represents that levels of quality of service is multicast tree and the data flow of Q1,

Thick-line arrow represents that levels of quality of service is multicast tree and the data flow of Q2;

Fig. 5. the message flow chart that the group membership adds in the network shown in Figure 4,

Multicast packet flows to

Control messages flows to

#1：Join(S，G1，Q2)，

#2：TA_Join_Req(S，G1，Q2)，

#3:Ring and BB consult,

#4:BB echo reply message,

#5:Ring notice C2 and Reg,

Other together;

Fig. 6. the message flow chart that the group membership leaves in the network shown in Figure 4,

Multicast packet flows to

Control messages flows to

#1：Leave(S，G1，Q2)，

#2：TA_Leave(S，G1，Q2)，

#3: notice C2 deletion branch,

#4:Ring reports to BB;

Fig. 7. the Experimental Network topological diagram that extracts according to Chinese Education and Research Net (CERNET), totally 36 nodes, wherein 8 main node: 0,2,15,18,19,20,21,33;

Fig. 8. link loss threshold value W ₀=0% o'clock multicast state is saved the graph of a relation of degree and concurrent group of quantity;

Fig. 9. link loss threshold value W ₀=7% o'clock multicast state is saved the graph of a relation of degree and concurrent group of quantity;

Figure 10. link loss threshold value W ₀=14% o'clock multicast state is saved the graph of a relation of degree and concurrent group of quantity;

Figure 11. border router Reg receives the Join that main frame sends, and (q) process chart during message is corresponding to the step 2 in the summary of the invention for s, g;

Figure 12. border router Ring receives TA_Leave, and (q) process chart during message is corresponding to the step 7 in the summary of the invention for s, g;

Figure 13. border router Ring receives TA_Join_Req, and (q) process chart during message is corresponding to step 3 in the summary of the invention and step 4 for s, g.

Embodiment

Use the application prerequisite of method proposed by the invention to be: the router in the network domains need be supported Differentiated Services, support basic IP multicast protocol such as PIM-SM (referring to RFC2362) and IGMP agreement (referring to RFC1112), wherein the IGMP agreement needs very little modification, makes group membership's adding leave group message can carry the levels of quality of service that needs.This method is only considered the IP multicast transmission in the network domains, an IP multicast mechanism (promptly a multicast group has only a sender, referring to RFC3569) at single source.This method can be supported existing various service class in the Differentiated Services architecture, also can support the service class that oneself defines.

Below we describe the method for multicasting of supporting different service quality in specification service network domain for example, as shown in Figure 4.This is a differentiated services network territory, and wherein C1, C2 and C3 are three core routers in the territory, represent with square; This network domains has six border router E1～E6, represents with circle; BB is the bandwidth broker in territory, and whether it allows the new network flow that arrives to enter the territory transmission according to the resource allocation conditions decision of entire domain.Suppose that it is that (S G1), sends multicast packet by E1 to the multicast group of S, and group of received member M1 and M2 receive data by E2 and E4 respectively, and M4 receives data by E6 that there is a source in this territory.The TA of E1 safeguards two multicast tree T1 (connecting with thin-line arrow) and T2 (being connected with thick-line arrow) in Fig. 4 in Fig. 4, (E1, E6 C3) support that levels of quality of service is the data passes of Q1 to T1, T2 (E1, E2, E3, E4, C1, C2) support that service quality is the data passes of Q2, the main frame that E3 connects is not this group membership, thereby exists bandwidth waste.

Our the member M3 of observation group adding group and leave the process of group.

Fig. 5 has shown M3 request adding group, and it has sent Join (S, G1, request message Q2) (being the #1 message among Fig. 5) to E5.After E5 receives message, check that the multicast forward table discovery oneself does not have the state of this group, it is to S clean culture TA_Join (S, G1, Q2) message (being the #2 message among Fig. 5).After E1 received this message, its TA entered the tree process of selecting, and found not exist the tree of supporting the E5 request, then initiate the achievement process, and consult (being the #3 message among Fig. 5) to BB; BB judges that present resource can meet this requirement, so return a response message (being the #4 message among Fig. 5) to E1; E1 has set up the new tree of E1-C1-C2-E5, and it finds that the concentrated tree T2 that exists of tree of TA maintenance can merge with this new tree, increased the new C2-E5 of branch so it notifies C2 to set T2, and notice E5 uses T2 to transmit multicast information (being the #5 message among Fig. 5).At this moment, E1 is the ingress router of multicast source s, can be designated as Ring, and E5 will be the egress router of M3, can be designated as Reg.

Fig. 6 has shown that M3 leaves the flow process of group.It sends Leave (S, G1, Q2) message (being the #1 message among Fig. 6) to E5 earlier.E5 has revised the multicast forward table of oneself then, has deleted the branch of the interface of M3.E5 is to E1 clean culture TA_Leave (S, G1, Q2) message (being the #2 message among Fig. 6) subsequently.After E1 receives this message, recomputate the link loss assessment of T2, find because E5 leaves back W (T2)＞W ₀So, need to adjust tree.Because this moment, T2 only supported the data passes of a group, so branch's (being the #3 message among Fig. 6) of notice C2 deletion C2-E5 will report also that at last the C2-E5 path supports other data flow transmission of Q2 level to cancel (being the #4 message among Fig. 6) to BB.

By last example as seen, core router C1～C3 does not need the maintenance service quality state, only need transmit operation.

We prove that by simulated experiment the method that the present invention proposes can effectively be saved multicast state.We extract the experiment topological structure that we need according to the backbone network of Chinese Education and Research Net (CERNET), as shown in Figure 7.Always have 36 network nodes in this topology, wherein 8 nodes such as Beijing, Shanghai are main node, and their flow is relatively large.We suppose the big node of flow, and the possibility that it adds certain group is big more.We define multicast state saving degree:

S _RThe quantity of the quantity of=concurrent multicast group * QoS number of levels/tree;

Because in the Traditional IP multicast, the multicast state quantity that router is safeguarded is directly proportional with concurrent multicast group, if support different service quality, number of states will double.And in our shared tree model, the multicast forwarding state that router need be safeguarded is directly proportional with shared tree quantity, so S _RThe degree that has reflected our scheme saving multicast state.

According to our method, if multicast conversation is supported different quality of service request, TA will be divided into the member of different levels of quality of service requests the identical child group of service quality so, is that each son group is sought the shared tree transmission then.On the whole, need the multicast group quantity of shared tree transmission to increase, and the scale of each group has reduced.Fig. 8～10 have reflected that state is saved the degree change rule in this case.In Fig. 8～10,12～16 members of multicast group scale average out to, 3 other service quality of level of support.The abscissa of each figure is represented concurrent multicast group quantity, and ordinate is represented state saving degree SR.By Fig. 8～10 as seen, along with the levels of quality of service number increases, multicast state is saved degree to be increased.Contrast this three figure, if increase link loss threshold value, forwarding state saving degree is improved many more.For example in Figure 10, when supporting 3 grades of service quality, the group state is saved and can be surpassed 8, and in order to safeguard current concurrent multicast conversation quantity, the transmission tree quantity that our scheme needs network domains to safeguard is that 1/8 of quantity is set in the transmission that traditional scheme need be safeguarded in other words.

This shows that the present invention has reached its intended purposes.

Claims (1)

1. the IP method of multicasting of supporting different service quality in specification service network domain, it is characterized in that, described method realizes that in the differentiated services network territory described differentiated services network territory comprises: a plurality of border routers, preserve state information with the monitoring transport stream; A plurality of territories inner core router is dispatched forwarding to stream aggregation, has extensibility; The bandwidth broker node in a described territory is represented with BB, and whether decision allows the new network flow that arrives to enter the territory to transmit according to the resource allocation conditions of entire domain; Each multicast group has a source, sends multicast packet by a border router, and a plurality of multicast members are arranged, and receives data by corresponding border router; These multicast group are transmitted information by corresponding multicast tree on this different service domains, and the service quality that obtains separately guarantees;

In this differentiated services network territory, realize described method of the present invention according to following steps successively:

Step 1. is represented with TA at a multicast tree administration module of each border router deploy in differentiated services network territory, will be safeguarded following data message at least in this module:

Multicast tree set TS, every tree wherein all use tree address unique in the territory to identify, and these are set all is to be root with TA place router, support different levels of quality of service, but every tree is only supported a kind of levels of quality of service;

Group-tree address respective function

Its group address was replaced by the tree address when transport stream entered different service domains through border router, and group address will be replaced back in the tree address when leaving this territory, the corresponding one or more trees of a group address, and these trees have been born the task of transmitting this group information jointly;

The link loss assessment W (T) of multicast tree is in order to assess the link loss that causes owing to redundant leaf node waste bandwidth; Thereby in module TA, be defined as follows parameter at least:

c _e: constitute the link cost of the limit e of tree T, default value is 1

C (T): the link cost of tree T, the link cost sum on all limits of formation T

n _G: set the group quantity that T supports transmission

G _i: set i the group that T supports transmission

π _T(G _i): expression tree T is by multicast group G _iThat part of link that uses is the subclass of T, promptly ${\mathrm{\π}}_T\left(G_i\right)\⊆T$

W ₀: predetermined link loss threshold value, be one less than 1 nonnegative real number

W (T): the link loss assessment of tree T

Group-tree address respective function

TS: the multicast tree set, it is a global variable

TStemp: interim multicast tree set, it is a temporary variable

TA is provided with following computing formula at least:

The link cost of tree T: C (T)=∑ _{E ∈ T}c _e

G _iLink cost on T: C (π _T(G _i))=∑ _{E ∈ π T ((it)}c _e

Tree T link loss assessment: $W\left(T\right)=\left[{\mathrm{\Σ}}_{i=1}^{n_G}C\left(T\right)\right]/\left[{\mathrm{\Σ}}_{i=1}^{n_G}C\left({\mathrm{\π}}_T\left(G_i\right)\right)\right]-1;$

When step 2. receives that as the interface I of border router multicast that main frame is sent joins request message, claim this moment this router to be the lower exit router of this multicast group in this territory, be designated as Reg, because it will be the outlet of multicast traffic stream leaving domain, this multicast message that joins request comprises the source address s and the requested service quality scale q of described multicast group address g, multicast at least, be designated as Join (s, g, q):

If the interface I of this egress router Reg is not at (s, g, in outgoing interface tabulation q), then module TA is packaged into unicast messages with Join message, be designated as TA_Join_Req (s, g, q), module TA it to source s direction clean culture, wait acknowledge message then, if this message adds successfully, then set up forwarding state, interface I is added in its outlet tabulation;

Step 3. is purpose unicast messages TA_Join_Req (s when border router receives with source s, g, q) time, claim that this router is the upstream ingress router of group g on this territory this moment, be designated as Ring, because it will be the inlet that multicast traffic stream enters the territory, its TA module is selected the tree process, at first put interim multicast tree set TStemp for empty, carry out following steps then successively:

Step 3.1. is optional one tree t in multicast tree set TS successively, then forwards step 3.4 to if all selected;

Step 3.2. does not perhaps comprise outlet boundary node Reg if this tree t does not support levels of quality of service q in Shu the leaf node, forward step 3.1 to;

Step 3.3. calculates the link loss assessment W (t) of tree t, if W (t)＜W ₀, then will set t and join among the interim multicast tree set TStemp; Otherwise, forward step 3.1 to;

Step 3.4. forwards step 4 to and carries out the achievement process, otherwise select one tree in TStemp if the interim multicast tree set TStemp of this moment is empty, is designated as t ₁, choice criteria is according to following priority orders:

A. link loss assessment minimum;

B. bear and transmit the multicast conversation minimum number;

C. select one at random;

Step 3.5. is consulted by module TA and described bandwidth broker Node B B, tree t ₁Whether can support this new multicast to add demand from lower exit router Reg:

If obtain permission, then egress router Reg sends adding successful respond message downstream, notifies it to transmit tree and is t ₁And the tree address, forward step 5 to and wait for forwarding;

Otherwise, with t ₁From interim multicast tree set TStemp, delete, forward step 3.4 to;

Step 4. is initiated to carry out the achievement process by upstream ingress router Ring, and execution in step is as follows:

Whether the module TA of this router of step 4.1. and BB negotiation allow to set up the path from Ring to Reg,

If be not allowed to, illustrate that current network resources is not enough to support the multicast request of Reg, then egress router Reg sends adding failure response message downstream, notifies it to join request and is rejected, and step 4 finishes;

If obtain allowing, remember that this paths is t _New, with t _NewThe multicast tree that is added to the TA maintenance of Ring is gathered among the TS;

If step 4.2. is t _NewBe the tree of unique support transmission group, for it distributes new tree address; Otherwise, have other one tree t among the multicast tree set TS _OldSupport that also (q), can consideration merge t to the transmission group for s, g _OldAnd t _New, calculate W (t _Old+ t _New):

If step 4.2.1. is less than W ₀Then merge, use t _OldTree address designation t _NewOtherwise, be t _NewDistribute new tree address;

Step 4.3. module TA notifies t _NewOn the territory on router set up corresponding multicast forwarding list item, this forwarding-table item comprises the incoming interface and the outgoing interface tabulation of address, the multicast packet of this tree at least;

Step 4.4. module TA egress router Reg downstream sends adding successful respond message, notifies it to transmit tree and is t _NewAnd appropriate address;

When step 5. is received the multicast information of group g of source s as upstream ingress router Ring, carry out repeating process:

Step 5.1.Ring is converted to corresponding tree address with the group address of this multicast data packet;

Territory inner core router on the step 5.2. tree is transmitted this multicast information according to this tree address;

After step 5.3. lower exit router Reg receives multicast information, original group address is replaced back in the tree address, pass from outlet;

When step 6. was received the multicast leave group message that main frame sends as the interface I of border router, this router was the lower exit router, and this message comprises group address g, source address s and requested service quality scale q at least, be designated as Leave (s, g, q), carry out following steps:

The module TA of this border router of step 6.1. deletes interface I from forwarding-table item;

This module of step 6.2. TA with Leave message be packaged into TA_Leave (s, g, q), it to source s direction clean culture;

Step 7. when border router receive unicast messages TA_Leave (s, g is in the time of q), this router and source s are connected to the upstream ingress router, its module TA finds corresponding tree t ' in multicast tree set TS, calculate the link loss assessment W (t ') of tree t ', if W (t ') 〉=W ₀, carry out tree according to following steps and adjust operation:

(q), then directly deletion comprises the branch of lower exit router Reg to step 7.1. for s, g, and notifies the core router in this branch to revise the multicast forwarding list item if tree t ' only supports to transmit multicast group;

Otherwise, tree t ' also supports to transmit other multicast group, the all-router except arrive lower exit router Reg branch of tree on the t ' constituted a new tree t, and the forwarding status information of "; distribute new tree address, and notify the router increase t in the branch of Reg " keeps the state information of t ' simultaneously;

The module TA notice BB of this router of step 7.2. Ring, multicast group (leave for s, g, discharges resource by lower exit router Reg branch q).

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