Background technology
Unidirectional multicast service in the application in Video service field more and more widely, vision signal requires in transmission course:
1) business is an one way traffic;
2) protection switch time is short, generally requires switching time within 50ms;
3) bandwidth availability ratio is high as far as possible;
4) inefficacy for program source has safeguard measure;
5) click end-to-end allocative abilities;
6) reliable transmission has accomplished that the road is just logical.
Broadcast television service is a kind of typical unidirectional multicast service, and one or more program source is generally arranged, and these program source can be video servers, also can be the transmission node on the network, and these nodes obtain the program of program source from upper layer network.
Referring to Fig. 1, exemplary block diagram for unidirectional multicast service transmission network, multicast source is done multicast message RP (the Rendezvous Point of net by state, convergent point) is transferred to each and economizes net (local area network (LAN)), economize on the RP that net and state do net multicast message handled after, be transferred to the terminal node of multicast again by switch, as STB (Set Top Box, set-top box), PC (Personal Computer, PC) etc.For example, in the television network broadcast of China, general program source all is the Chinese Central Television (CCTV), the program of CCTV-1,2,4,7,10, channels such as 11 and 12 can be transferred to each by the dried net of state in program source and economize net, RP that net and state do net decodes and the editing of program economizing then, and the terminal use is arrived in the program transmission behind the editor.
There is a kind of transmission of unidirectional multicast service to realize in the prior art by on transmission equipment, carrying out static configuration, static configuration is by webmaster or order line the cross-over configuration of multicast service to be gone down, the main information of configuration has the situation that professional plate position, light mouth and time slot etc. intersect that goes up, and professional down information such as plate position, light mouth and time slot.After configuring static the intersection, the cross unit of transmission equipment will be crossed to the multicast service that is carried on source plate position, light mouth and time slot on corresponding purpose plate position, light mouth and the time slot according to configuration information.
For example; at first do net configuration MSP (Multiplex Section Protection in state; multiplex section protection); by business board multicast service is uploaded to transmission equipment in the Chinese Central Television (CCTV) then; on transmission equipment, carry out the configuration of multicast service; be that configuring static intersects; multicast service is transferred out from a circuit that has disposed MSP; crossing or tangent node at the dried net of state and province's net downloads to this locality with multicast service from business board by top mode; again upload on the transmission equipment of province's net through decoding or editor, the net transport plane carries out the transmission of multicast service in province again.
Carry out in the network of multicast transmission in above-mentioned employing static configuration; resist technology generally is MSP (Multiplex SectionProtection; multiplex section protection), PP (Path Protection; path protection) and SNCP traditional protection technologies such as (Sub-Network ConnectionProtection, SNCPs).
Wherein, MSP uses APS (Automatic Protection Switching, APS) agreement to finish protection, by the alarm triggered of multiplex section level.Use the resource on the active link during normal transmission multicast service; the protection link can transmit extra business; under the situation that active link lost efficacy, transmission equipment according to configuration information and APS agreement with professional auto switching to the protection link, multicast service is protected.
PP and SNCP are other protections of channel level; do not use the APS agreement; disposing the two of multicast service at the source end when configuring static intersects sends out; promptly be configured to simultaneously on active link and the protection link; select receipts at the Su Duan of multicast service (receiving terminal) according to the situation of multicast service; promptly according to active link and the quality of protecting business on the link the reasonable business of situation is passed through to intersect, download to this locality at Su Duan.
It is above-mentioned that to carry out unidirectional multicast service transfer bandwidth utilance by static configuration lower.
Another kind is to use ASON (Automatically Switched Optical Network, ASON) intelligence configuration multicast group, and when network broke down, the unidirectional multicast service from the multicast source to the destination node can heavy-route.
Existing ASON has two kinds of implementations: the one, and support point is created multicast group to the signaling of multiple spot, and a multicast group is exactly a LSP (Label Swithing Path, a label switched path), all is a LSP in signaling aspect and resource aspect promptly; The second way is each root node to the path of leaf node all is a LSP, can accomplish resource-sharing in the time of resource allocation in a multicast group.Above dual mode is all supported the recovery of multicast service, promptly can carry out heavy-route under the situation of link occurs fault, sets up a new LSP by the cooperation of route and signaling and replaces original LSP, recovers multicast service.Compare with static configuration, carry out the bandwidth availability ratio height of multicast transmission by ASON.
Above-mentioned employing ASON carries out the method for multicast transmission, when network breaks down, can only adopt the heavy-route mode to recover multicast service, can not recover multicast service in 50ms usually, causes the time delay of multicast service transmission, can not satisfy the demand of video traffic.
In realizing process of the present invention, the inventor finds that existing unidirectional multicast service exists the contradiction of coordinating between bandwidth availability ratio and the protection switch time demand, causes the bandwidth availability ratio time low or the recovery multicast service long.
Summary of the invention
In order to make multicast service make full use of the network bandwidth, and guarantee business switching time, the embodiment of the invention provides a kind of method, system and equipment that guarantees the multicast service reliable transmission.Described technical scheme is as follows:
The embodiment of the invention provides a kind of method that guarantees the multicast service reliable transmission, and described method comprises:
Calculate main path;
Increase the cost value of the link of main path process described in the constraints, calculate the backup path that separates with described main path according to shortest-path first algorithm based on constraint; Or, the node of getting rid of described main path process as constraints, is calculated the backup path that separates with described main path according to the shortest-path first algorithm based on constraint;
In multicast group range, set up described main path and backup path in the mode of resource-sharing;
On described main path and backup path, send multicast service.
The embodiment of the invention also provides a kind of system that guarantees the multicast service reliable transmission, and described system comprises:
Multicast source devices is used to calculate the backup path that main path and calculating separate with described main path, and sets up described main path and backup path with the resource sharing mode in multicast group range, sends multicast service on described main path and backup path;
Wherein, calculating the backup path that separates with described main path comprises:
Increase the cost value of the link of main path process described in the constraints, calculate the backup path that separates with described main path according to shortest-path first algorithm based on constraint; Or, the node of getting rid of described main path process as constraints, is calculated the backup path that separates with described main path according to the shortest-path first algorithm based on constraint;
Multi-cast terminal equipment is used for selectivity and receives the multicast service that described multicast source devices sends on main path and backup path.
The embodiment of the invention also provides the system of another kind of assurance multicast service reliable transmission, and described system comprises:
Main multicast source devices is used to calculate main path, sets up described main path with the resource sharing mode in multicast group range, sends multicast service on described main path;
Standby multicast source devices is used to calculate the backup path that separates with described main path, sets up described backup path with the resource sharing mode in multicast group range, sends multicast service on described backup path;
Wherein, calculating the backup path that separates with described main path comprises:
Increase the cost value of the link of main path process described in the constraints, calculate the backup path that separates with described main path according to shortest-path first algorithm based on constraint; Or, the node of getting rid of described main path process as constraints, is calculated the backup path that separates with described main path according to the shortest-path first algorithm based on constraint;
Multi-cast terminal equipment is used for the multicast service that selectivity receives described main multicast source devices and the transmission of standby multicast source devices.
Further, the embodiment of the invention also provides a kind of multicast source devices, and described equipment comprises:
The main path computing module is used to calculate main path;
The backup path computing module is used to calculate the backup path that the main path that calculates with described main path computing module separates;
Wherein, calculating the backup path that separates with described main path comprises:
Increase the cost value of the link of main path process described in the constraints, calculate the backup path that separates with described main path according to shortest-path first algorithm based on constraint; Or, the node of getting rid of described main path process as constraints, is calculated the backup path that separates with described main path according to the shortest-path first algorithm based on constraint;
Module is set up in the path, is used in multicast group range setting up the path that described main path computing module and described backup path computing module calculate with the resource sharing mode;
The multicast service sending module is used for setting up the path transmission multicast service that module is set up by described path.
The beneficial effect of the technical scheme that the embodiment of the invention provides is:
The embodiment of the invention is by setting up main path and backup path between multicast source and multicast destination node, and the backup path of setting up satisfies the condition of as far as possible separating with main path, can improve utilization rate of network resource when guaranteeing switching time.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, embodiment of the present invention is described further in detail below in conjunction with accompanying drawing.
The embodiment of the invention is by setting up main path and backup path between multicast source and multicast destination node, and the backup path of setting up satisfies the condition of separating with main path, can improve utilization rate of network resource when guaranteeing switching time.
The embodiment of the invention provides a kind of method that guarantees the multicast service reliable transmission, comprising:
Calculate main path and the backup path that calculating separates with main path, in multicast group range, set up main path and backup path with the resource sharing mode;
Send multicast service at main path and backup path.
Be the method that the example introduction guarantees the multicast service reliable transmission with single multicast source and two multicast sources respectively below.
Embodiment 1
Referring to Fig. 2, present embodiment is established as example with main path and backup path by same multicast source and describes, and guarantees that the method for multicast service reliable transmission specifically may further comprise the steps:
Step 101: for multicast source distributes multicast identifier and service identification.
An all shared sign of path of multicast identifier all multicast destination nodes that are multicast source on the multicast group; Service identification is in order to the multicast service of sign from multicast source to same multicast destination node.
Step 102: calculate main path, calculate the backup path that separates with main path then from multicast source to the multicast destination node.
When setting up the path, by OSPF (Open Shortest Path First, Open Shortest Path First)-TE (TrafficEngineering, traffic engineering) diffusion topological sum TE information, adopt CSPF (Constraint-based Shortest Path First, SPF based on constraint) algorithm carries out path computing, with the multicast source that calculates to the optimal path of multicast destination node as main path, the constraints of optimal path can be specified by the user, separates with the path such as balanced bandwidth, the shortest jumping figure etc.
When present embodiment calculates backup path, make backup path and main path accomplish to separate to greatest extent.Specifically can be by the cost value of the link of main path process in the constraints that increases the CSPF algorithm, promptly the link cost to the main path process is weighted, and makes the link of not selecting when calculating backup path on the main path; Also can in constraints, dose the node of getting rid of the main path process; Accomplish that main path separates to greatest extent with backup path, improve bandwidth utilization.
Referring to Fig. 3, suppose that node A is a multicast source, Node B, node C, node D, node E and node F are the multicast destination node, calculate the main path of A to B, C, D, E and F respectively, among the figure b1, c1, d1, e1 and f1 be respectively from A to B, the main path of C, D, E and F; Calculating A behind the main path of each multicast destination node, to separate as constraints with main path, calculate the backup path of A to the main path of B, C, D, E and F respectively, referring to Fig. 4, b2, c2, d2, e2, f2 are respectively the backup path of corresponding main path among Fig. 3 among the figure.A is ABD to the main path d1 of D among Fig. 3, and its backup path is the d2 among Fig. 4, i.e. ACFED, from figure the position of node as can be seen, ABD has accomplished to separate to greatest extent with ACFED.
After calculating active and standby path, to multicast source, multicast source carries out the transmission of multicast service according to the active and standby routing information of storage with the information stores in active and standby path.
Step 103: in multicast group range, set up main path and backup path with the resource sharing mode.
Setting up main path and backup path can realize by signaling, when the resource-sharing mode here refers to set up the path, for the coincidence link in the same multicast group, use identical time slot on the optical fiber, promptly on the multicast equipment of the upstream of this section link, intersect make can resource-sharing business use identical light-emitting window and time slot, the interior different business of multicast group just can use identical link circuit resource to transmit like this.
For example, node A is the program source of the dried network of province, and then province TV station uploads to the CCTV on the transmission network from branch road with the business board of this province program by transmission equipment; A knows that two multicast service path A BD with same multicast group id and ABE pass through A and transmit, and resource-sharing can be carried out in these two multicast service paths between AB, then the A time slot that will go up professional light mouth is crossed on certain time slot of a light mouth that links to each other with Node B, multicast service just can have been realized the resource-sharing of AB section by the link transmission between the AB to B then; B knows that two multicast service path A BD with same multicast group id and ABE pass through B and transmit, and can not carry out resource-sharing, therefore B will be crossed on certain time slot of certain the light mouth that links to each other with D from the light mouth time slot that carries from the multicast service that A transmits, also multicast service is crossed on certain time slot of certain the light mouth that links to each other with E simultaneously, so just can multicast service be transferred to D and E respectively by link BE and BD.
Step 104: multicast source sends multicast service by main path and the backup path of setting up to the multicast destination node.
The node that receives multicast service can carry out resource-sharing according to multicast identifier on the coincidence link in path, promptly on the coincidence link in these paths, use identical time slot (bandwidth of transport multicast business or passage), to reduce the occupancy of Internet resources.
For example, A is ABD to the main path of D among Fig. 3, A is ABE to the main path of E, this two paths overlaps in the AB section, therefore A by ABD and ABE respectively when D sends different multicast service with E, can carry out resource-sharing in the AB section, at this moment need set up the single-shot of multicast service, set up the two of multicast service at B and send out at A.
Above-mentioned is that example is illustrated with the resource-sharing on the coincidence link between the main path, further, on the coincidence link between the backup path, and it is identical with the processing mode of main path to carry out the processing mode of resource-sharing on the coincidence link between backup path and the main path.
Step 105: the multicast destination node optionally receives the multicast service that transmits on main path and the backup path according to service identification.
In Network Transmission, owing to network congestion or other reason, can have influence on the multicast service quality of signals of transmitting on main path or the backup path, at this moment the multicast destination node is according to the quality of the multicast service signal quality that transmits on the active and standby path, the multicast service on the good path of selective reception signal quality.
By calculating and setting up active and standby path, the multicast destination node receives the multicast service on two paths simultaneously, when wherein a paths breaks down, also can not influence the transmission of multicast service in the above-mentioned steps.Simultaneously, when fault is difficult to recover, can sets up a new route by the mode of heavy-route, and store the information in this path at multicast source, if the new route of setting up has the link with the paths merge of having set up, can on the link that overlaps, proceed resource-sharing.
In the above-mentioned steps by between multicast source and multicast destination node, setting up main path and backup path, and separate to greatest extent between main path and the backup path, have influence on the multicast service of another paths when having avoided a paths to break down, improved the reliability of multicast transmission; Can carry out resource-sharing between the multicast path of setting up, improve utilization rate of network resource.
Embodiment 2
Present embodiment is an example with two multicast sources, and these two multicast sources are respectively main multicast source and standby multicast source, and the selection of main multicast source and standby multicast source can artificially be specified, and also can produce automatically by certain agreement.Referring to Fig. 6, guarantee that the method for multicast service reliable transmission specifically may further comprise the steps:
Step 201: be respectively main multicast source and distribute identical multicast identifier with standby multicast source.
An all shared sign of path of multicast identifier all multicast destination nodes that are two multicast sources on the multicast group.When transport multicast is professional, can to the coincidence link in the path of multicast destination node, carry out resource-sharing at two multicast sources according to multicast identifier, when promptly on the coincidence link in these paths, transmitting the multicast service of same multicast group, can use identical time slot.
Step 202: main multicast source is respectively each multicast service with standby multicast source and distributes identical service identification.
For the multicast service from main multicast source and standby multicast source to the same multicast destination node distributes a service identification, represent that this is same multicast service, two paths to the same multicast destination node of main multicast source and the foundation of standby multicast source can be associated according to service identification.
By the distribution service sign, the multicast destination node is received according to the choosing that this service identification carries out multicast service, the service identification of distribution can be transferred to the multicast destination node by signaling message.
Step 203: main multicast source calculates the main path of multicast destination node, sets up main path with the resource sharing mode in multicast group range.
Identical among the computational methods of main path and the embodiment 1, all be to adopt the CSPF algorithm, set up in the process of main path, when overlapping link, carry out resource-sharing, the identical time slot on the use same fibre with other path.Main path is notified standby multicast source with the information of this main path after setting up.
Step 204: the main path information that standby multicast source is set up according to main multicast source to the multicast destination node, calculate the backup path that separates with this main path, the mode with resource-sharing in multicast group range is set up backup path.
The main path information that standby multicast source is set up according to main multicast source to the multicast destination node, when setting up backup path, get rid of this main path, set up the backup path of this main path, the computational methods of backup path are with identical described in the embodiment 1, all be to adopt the CSPF algorithm, and when calculating backup path, satisfy the constraints of the CSPF that separates with main path, make the backup path that calculates accomplish to separate to greatest extent with main path.Referring to Fig. 7, for example main multicast source A is ABE to the main path that multicast destination node E sets up, standby multicast source C will separate as constraints with main path ABE when calculating backup path, get rid of main path ABE, C is CFE to the backup path that E sets up among the figure, the position of node from figure, ABE has accomplished to separate to greatest extent with CFE.
With the standby multicast source of information stores of the backup path set up, standby multicast source carries out the transmission of multicast service according to the backup path information of preserving.
In the process of above-mentioned road construction, on the link that overlaps, carry out resource-sharing, improve utilization of network bandwidth.
Step 205: main multicast source and standby multicast source send multicast service respectively on main path of setting up and backup path.
In the multicast service transmission process, according to multicast identifier, carry out resource-sharing on the coincidence link of main path in same multicast group and backup path, for example, it can be the coincidence link between the main path of certain two multicast service, also can be the coincidence link between the backup path of the main path of a multicast service and another multicast service, or the coincidence link between the backup path of two multicast services.
Step 206: the multicast destination node optionally receives the multicast service that transmits on main path and the backup path according to service identification.
The multicast destination node selects the time receiving between active and standby path, at first judge according to service identification whether the multicast service that never receives with the path is same multicast service, if same multicast service, then according to the quality of multicast service signal quality, the measured multicast service of select-out signal matter in the multicast service that receives with the path never.As shown in Figure 7, it is same multicast service that multicast destination node D judges what transmit from ABD and CFED two paths by service identification, quality according to the multicast service signal quality of ABD and CFED transmission, if it is good to pass the signal quality of coming from ABD, then select the multicast service of main multicast source A transmission; Otherwise, the multicast service of selecting standby multicast source C to transmit.
When network breaks down, when promptly arriving the path failure of certain multicast destination node, then failure path is carried out heavy-route, guarantee that this multicast destination node has two paths can receiving multicast business all the time; If two paths to this multicast destination node all lost efficacy, then main multicast source can carry out heavy-route so that recover multicast service.As shown in Figure 7, for example interruption has taken place in two paths ABE and the CFE to multicast destination node E, and then main multicast source A can heavy-route goes out ABDE and recovers multicast service.
Further, the path of setting up for heavy-route, if according to multicast identifier, this path have with its same multicast group in the link that coincides of path, when the multicast service of the same multicast group of transmission, also can on the link of these coincidences, carry out resource-sharing.
Above-mentioned steps is by backing up multicast source, when one of them multicast source breaks down, therefore the transmission of unidirectional multicast service can't be affected, and the multicast destination node can continue to receive the multicast service of standby multicast source, the reliability when having strengthened unidirectional multicast service transmission; And between the path that has the coincidence link, carry out resource-sharing, under the prerequisite that guarantees switching time, improved network resource utilization.
Embodiment 3
Referring to Fig. 8, the embodiment of the invention provides a kind of system that guarantees the multicast service reliable transmission, comprising:
Multicast source devices 301 is used to calculate the backup path that main path and calculating separate with main path, and sets up main path and backup path with the resource sharing mode in multicast group range, sends multicast service on main path and backup path;
Multi-cast terminal equipment 302 is used for the multicast service that selectivity receiving group source device 301 sends on main path and backup path.
Wherein, multicast source devices 301 also comprises:
The service identification distribution module is used to main path and backup path to distribute a service identification;
Correspondingly, multi-cast terminal equipment 302 comprises:
The multicast service judge module is used for judging according to service identification whether the multicast service that never receives with the path is identical multicast service;
Multicast service is selected module, is used for when multicast service judge module when never to judge multicast service with the path reception be identical multicast service the measured multicast service of select-out signal matter.
Further, multicast source devices 301 also comprises:
The multicast identifier distribution module is used to distribute a multicast identifier;
Correspondingly, this system also comprises:
Intermediate equipment is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group, if carry out resource-sharing on the coincidence link of main path in multicast group range and backup path.
Further, multicast source devices 301 also is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group, if carry out resource-sharing on the coincidence link of main path in multicast group range and backup path.
Embodiment 4
Referring to Fig. 9, present embodiment also provides a kind of system that guarantees the multicast service reliable transmission, comprising:
Main multicast source devices 401 is used to calculate main path, sets up main path with the resource sharing mode in multicast group range, sends multicast service on main path;
Standby multicast source devices 402 is used to calculate the backup path that the main path that calculates with main multicast source devices 401 separates, and sets up backup path with the resource sharing mode in multicast group range, sends multicast service on backup path;
Multi-cast terminal equipment 403 is used for the multicast service that selectivity receives main multicast source devices 401 and 402 transmissions of standby multicast source devices.
Wherein, main multicast source devices 401 also comprises:
Main business sign distribution module is used to main path to distribute a service identification;
Main communication module is used to notify the main path that main multicast source devices 401 calculates and the service identification of distribution;
Correspondingly, standby multicast source devices 402 also comprises:
Be equipped with communication module, be used to receive the notice of main communication module, from notice, extract the service identification of main path;
Multi-cast terminal equipment 403 comprises:
The multicast service judge module is used for judging according to service identification whether the multicast service that never receives with the path is identical multicast service;
Multicast service is selected module, is used for when multicast service judge module when never to judge multicast service with the path reception be identical multicast service the measured multicast service of select-out signal matter.
Further, main multicast source devices 401 also comprises:
The multicast identifier distribution module is used to distribute a multicast identifier, and is notified to standby multicast source devices 402 by main communication module;
Correspondingly, system also comprises:
Intermediate equipment is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group, if carry out resource-sharing on the coincidence link of main path in multicast group range and backup path.
Further, main multicast source devices 401 also is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group with standby multicast source devices 402, if carry out resource-sharing on the coincidence link of main path in multicast group range and backup path.
Embodiment 5
Referring to Figure 10, present embodiment provides a kind of multicast source devices, comprising:
Main path computing module 501 is used to calculate main path;
Backup path computing module 502 is used to calculate the backup path that the main path that calculates with main path computing module 501 separates;
Module 503 is set up in the path, is used in multicast group range setting up the path that main path computing module 501 and backup path computing module 502 calculate with the resource sharing mode;
Multicast service sending module 504 is used for setting up the path transmission multicast service that module 503 is set up by the path.
Further, this multicast source devices also is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group, if carry out resource-sharing on the coincidence link of main path in multicast group range and backup path.
Embodiment 6
Referring to Figure 11, present embodiment provides a kind of multicast service forwarding unit, comprising:
Multicast group judge module 601 is used for judging according to multicast identifier whether different multicast services is professional in the same multicast group;
Resource-sharing module 602, being used for judging different multicast services when multicast group judge module 601 is in the same multicast group when professional, carries out resource-sharing on the coincidence link in different paths in multicast group range;
Professional forwarding module 603 is used for transmitting the multicast service that receives according to the resource-sharing mode of resource-sharing module 602.
The embodiment of the invention is by setting up main path and backup path between multicast source and multicast destination node, and separate to greatest extent between main path and the backup path, have influence on the multicast service of another paths when having avoided a paths to break down, on the coincidence link between the multicast path of setting up, carry out resource-sharing, both guarantee the switching time of multicast service, improved utilization rate of network resource again; Back up by multicast source simultaneously, can guarantee under the situation that a multicast source lost efficacy, not influence the transmission of multicast service, the reliability when further having strengthened multicast service transmission the multicast transmission business.
The embodiment of the invention can realize that corresponding software can be stored in the storage medium that can read, for example in the hard disk of computer, CD or the floppy disk by software.
The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.