CN103023780A - Method and device for routing computation - Google Patents
Method and device for routing computation Download PDFInfo
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- CN103023780A CN103023780A CN2012105193406A CN201210519340A CN103023780A CN 103023780 A CN103023780 A CN 103023780A CN 2012105193406 A CN2012105193406 A CN 2012105193406A CN 201210519340 A CN201210519340 A CN 201210519340A CN 103023780 A CN103023780 A CN 103023780A
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Abstract
The invention provides a method for routing computation. The method is used in routing computation from a source node to a destination node, a plurality of domains are contained from the source node to the destination node, and the method comprises that a path computation unit of the current domain determines bidirectional label switching paths from the current domain to adjacent domains of the current domain, and conducting resource reservation for bidirectional label switching paths, wherein all coincident path sections are subjected to resource reuse if coincident path sections exist in bidirectional label switching paths. The invention also provides a device for routing computation. According to the method and the device, resources are reused during resource reservation, so that the resource waste can be reduced.
Description
Technical field
The present invention relates to the communications field, relate in particular to a kind of route computing method and device.
Background technology
Adopting AS (Autonomous System, autonomous system) in the multiple-domain network of dividing, if determined the territory sequence, can adopt BRPC (Backward-Recursive PCE-BasedComputation, the backward recursive routing algorithm) carries out cross-domain path computing, lacked constrained path most.
RFC5441 was described the BRPC algorithm in (Request For Comments is called for short RFC, Request for Comment), and this algorithmic procedure depends on the communication between the co-operating PCE (Path Computation Element, path-calculating element).PCC (Path Computation Clients, path calculating client) sends PCReq (Path Computation Request, path computing request) message to the PCE in its territory.This message is transmitted between the PCE in each territory, until request arrives the PCE that is responsible for calculating LSP (Label Switched Path, label switched path) territory, destination node place.PCE in the purpose territory creates a virtual shortest path tree (VirtualShortest Path Tree who is comprised of the potential path that arrives destination node, VSPT), and in PCRep (Path Computation Response, path computing response), this tree is passed to previous PCE.Then each PCE increases VSPT successively, and it is passed to passback, until the PCE in territory, source node place, this PCE uses VSPT to select an end to end path, and the path is sent to PCC.
As shown in Figure 1, the BRPC algorithm is done following agreement:
1) BN-en (k, i): one group of entry border node of territory i (boundary node of link field (i-1)), wherein BN-en (k, i) is k the entry border node of territory i;
2) BN-ex (k, i): one group of outlet boundary node (boundary node of link field (i+1)) of territory i, wherein BN-ex (k, i) is k the outlet boundary node of territory i;
3) VSPT (i): the multiple spot that is returned to PCE (i-1) by PCE (i) is to the tree of (MultiPoint To Point) a bit.
Concrete calculation procedure is as follows:
First node PCC sends first territory PCE with path computing request in step 1:AS (1) territory, and then path computing request is transmitted the PCE along the order in the territory of territory sequence appointment along a plurality of territories, until arrive the PCE (n) in territory, destination node place.
Step I: calculate VSPT (i) for i=n to 2:PCE (i), this tree is comprised of the shortest constrained path between each BN-en (j, i) and TE (Traffic Engineering, traffic engineering) the LSP destination node, as shown in Figure 1.PCE (i) by it TED (Traffic Engineering Database,
The traffic engineering storehouse), the Inter-AS link (not existing during i=n) of link field (i) and territory (i+1) and the information among the VSPT (i+1) (not existing during i=n) are calculated.
Step n: the PCE (1) in last territory, source node place calculates the shortest end-to-end constrained path from the source node to the destination node, and corresponding path is returned to request PCC (source node) with PCRep, and the cross-domain path computing process of BRPC finishes.
Said process is the general process that the BRPC algorithm calculates, yet for each PCE (i), corresponding TED is unsettled (being that BRPC path resource may be taken by other business), resource is not shared by other business when guaranteeing that path that BRPC calculates is set up, and usually needs each PCE (i) that the resource in corresponding this territory among the VSPT (i) is reserved.By the BRPC algorithm as can be known, if there is m entry border node in the responsible territory of PCE (i), then need the m paths of this territory calculating generation and the resource on maximum m bar Inter-AS (Inter-Autonomous System is between autonomous system domains) link are reserved.Yet what last foundation was used when BRPC calculated cross-domain route only is one, and the reservation resource in other paths is to set up or just be released after certain period in business.As shown in Figure 1, there be j entry border node in territory (i), and the VSPT (i) that PCE (i) calculate to produce will be comprised of VSPT (i+1) and the j bar path by entry border node entry border node of (i) to the territory of territory (i+1).This j paths (comprising path and domain-to-domain link in the territory) all will independently be reserved (when resource reservation is unsuccessful, will cause branch's failure) to its resource requirement.Finish VSPT (1) (in fact at this time being end-to-end path) in PCE (1) calculating, it is front that the professional PATH signaling of setting up arrives territory (i), the non-optimal path of j-1 bar is reserved resource and all can not be used by other business in the territory (i), and this causes in the territory (i) some business normally to set up possibly.
Can see that can be successfully established for guaranteeing the path that BRPC calculates, BRPC can reserve the every territory resource on the order path, territory.And such reservation all will cause in the territory in every territory and the inter-domain resource waste, affects the normal foundation of other business.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of route computing method and device, reduces the wasting of resources.
In order to address the above problem, the invention provides a kind of route computing method, be applied to source node in the route calculating of destination node, source node comprises a plurality of territories to destination node, comprising:
The path-calculating element of the current field determines that described the current field is to the bidirectional label exchange path of its adjacent domains;
For described bidirectional label exchange path carries out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence carried out resource multiplex.
Said method also can have following characteristics, and described route segment to each coincidence carries out resource multiplex and comprises:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
Said method also can have following characteristics, and described route segment to each coincidence carries out resource multiplex and comprises:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
Said method also can have following characteristics, described method also comprises: if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
Said method also can have following characteristics:
When determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, pre-conditioned if path constraint satisfies, select to overlap each other the maximum bidirectional label exchange path of route segment.
Said method also can have following characteristics:
Described pre-conditioned comprising: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
Said method also can have following characteristics:
Determine that described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
When described the current field is that described method also comprises when not comprising the territory of described source node:
Determine described the current field behind the bidirectional label exchange path of its adjacent domains, the generating virtual shortest path tree;
Whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
Said method also can have following characteristics:
Described the current field is when not comprising the territory of described destination node, branch's route that the leaf node of non-described the current field is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
The present invention also provides a kind of route calculation element, comprising:
The path determination module is used for determining that the current field is to the bidirectional label exchange path of its adjacent domains;
The resource reservation module is used to described bidirectional label exchange path to carry out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence is carried out resource multiplex.
Said apparatus also can have following characteristics, and described resource reservation module is carried out resource multiplex to the route segment of each coincidence and comprised:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
Said apparatus also can have following characteristics, and described resource reservation module is carried out resource multiplex to the route segment of each coincidence and comprised:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
Said apparatus also can have following characteristics, described resource reservation module also is used for: if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
Said apparatus also can have following characteristics, and described path determination module also is used for:
When determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, pre-conditioned if path constraint satisfies, select the maximum bidirectional label exchange path of route segment that overlaps each other.
Said apparatus also can have following characteristics, described pre-conditioned comprising: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
Said apparatus also can have following characteristics, and described device also comprises: the path transmission module, wherein:
Described path determination module determines that described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
Described path determination module also is used for, and when described the current field is when not comprising the territory of described source node, determines described the current field behind the bidirectional label exchange path in its next territory, the generating virtual shortest path tree;
Described path transmission module is used for, when described the current field is when not comprising the territory of described source node, whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
Said apparatus also can have following characteristics, described path transmission module also is used for, when described the current field is when not comprising the territory of described destination node, branch's route that the leaf node of non-described the current field in the described virtual shortest path tree is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
The application comprises following advantage:
When 1) carrying out resource reservation, the coincidence route segment of each branch among the VSPT (i) is carried out resource multiplex, reduced resource occupation.
2) when calculating path, satisfy when pre-conditioned at path constraint, select to overlap each other the maximum bidirectional LSP of route segment.Pre-conditioned comprising: resource utilization required to be higher than the path optimality is required and/or the current field available resources are lower than resource threshold.This scheme is so that as far as possible coincidence of each individual path among the VSPT (i); Because overlapping route segment can be multiplexing with a resource, be calculated to be power with regard to further having reduced the requirement to resource quantity on the duplicate paths, having improved like this; Reduce simultaneously the reservation resource in each territory, improved the resource utilization in each territory.
3) owing to increased inspection to VSPT (i), delete during for the useless branch upstream passing among the VSPT (i), notify simultaneously PCE in the useless branch to discharge reservation resource on the individual path, shortened the resource reservation time.
Description of drawings
Fig. 1 is the VSPT tree schematic diagram in the BRPC algorithm computational process;
Fig. 2 is the territory (i) of all embodiment of the present invention and the topological schematic diagram of VSPT (i+1);
Fig. 3 is the calculating path schematic diagram of embodiment one;
Fig. 4 is result of calculation VSPT (i) schematic diagram of embodiment one;
Fig. 5 is the calculating path schematic diagram of embodiment two;
Fig. 6 is VSPT (i) schematic diagram that embodiment two does not delete leaf node;
Fig. 7 is result of calculation VSPT (i) schematic diagram of embodiment two;
Fig. 8 is the calculating path schematic diagram of embodiment three;
Fig. 9 is VSPT (i) schematic diagram that embodiment three does not delete leaf node;
Figure 10 is result of calculation VSPT (i) schematic diagram of embodiment three;
Figure 11 is embodiment of the invention route calculation element block diagram.
Embodiment
For making the purpose, technical solutions and advantages of the present invention clearer, hereinafter in connection with accompanying drawing embodiments of the invention are elaborated.Need to prove that in the situation of not conflicting, the embodiment among the application and the feature among the embodiment be combination in any mutually.
In addition, although there is shown logical order in flow process, in some cases, can carry out step shown or that describe with the order that is different from herein.
The embodiment of the invention provides a kind of route computing method, is applied to source node in the route calculating of destination node, and source node comprises a plurality of territories to destination node, comprising:
The path-calculating element of the current field determines that described the current field is to the bidirectional label exchange path of its adjacent domains;
For described bidirectional label exchange path carries out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence carried out resource multiplex.
In a kind of alternative of present embodiment, in the following way the route segment of each coincidence carried out resource multiplex:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
In a kind of alternative of present embodiment, in the following way the route segment of each coincidence carried out resource multiplex:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
In a kind of alternative of present embodiment, if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
In a kind of alternative of present embodiment, pre-conditioned if path constraint satisfies when determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, select the maximum bidirectional label exchange path of route segment that overlaps each other.
Wherein, described pre-conditioned including but not limited to: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
In a kind of alternative of present embodiment, described definite described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
When described the current field is that described method also comprises when not comprising the territory of described source node:
Determine described the current field behind the bidirectional label exchange path in its next territory, the generating virtual shortest path tree;
Whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
In a kind of alternative of present embodiment, described the current field is when not comprising the territory of described destination node, described method also comprises: branch's route that the leaf node of non-described the current field in the described virtual shortest path tree is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
The below uses the present invention in the BRPC algorithm that defines and further specifies the present invention as example in existing RFC5441.But the invention is not restricted to this.
The below selects the BRPC backward recursive behind the modification and perfection to calculate embodiment and specifies how to use the inventive method in cross-domain path computing, and the reservation and the resource that reduce resource in the BRPC process discharge.Embodiment only describes the computational process of PCE (i) herein, and in this computational process, the link topology is done as a whole calculating in domain-to-domain link and the territory.
The method comprises:
Step 101: for i=n to 2, PCE (i) calculates VSPT (i) according to the path constraint that carries in the computation requests (such as Least-cost, resource utilization etc.).
Wherein, satisfy when pre-conditioned at path constraint:
In the present embodiment, pre-conditioned comprising: to resource utilization require to be higher than to the path optimality require or these territory available resources less than resource threshold;
Concrete:
If in the path constraint that carries in the path computing request resource utilization required to be higher than the path optimality is required or this territory available resources during less than resource threshold, when then PCE (i) calculates VSPT (i), as far as possible the overlapping of path that guarantees each branch among the VSPT (i) (adopted the mode of i-1 paths cost before adjusting when calculating i bar individual path, so that the i paths overlaps with front i-1 paths.The mode that realizes is a lot, is not limited to the mode that this exemplifies), execution in step 102;
When if the requirement of unmatchful resource utilization or this territory available resources are greater than resource threshold in the path constraint that carries in the path computing request, then PCE (i) calculates VSPT (i), execution in step 102 according to general BRPC algorithmic procedure;
Step 102: the m paths that calculates is carried out resource reservation;
To m:PCE (i) to j bar individual path (comprising the inter-domain path between the path and downstream domain in this territory, territory) when carrying out resource reservation, need judge whether j bar individual path exists with front j-1 bar branch overlaps route segment for path j=1.Overlap route segment if exist, then process respectively according to resource hierarchy:
If electricity layer resource then no longer carried out the reservation of electricity layer resource (being time slot) to overlapping route segment, but multiplexing front overlaps the time interval resource that route segment is reserved for this;
If photosphere resource, then multiplexing (wavelength resource that multiplexing front has been reserved for this coincidence route segment) carried out in the wavelength resource of outside photosphere link, simultaneously to the resource of intra-node (such as optical-electrical converter, internal optical fiber, channel join-splitting device) also as far as possible multiplexing, no longer resource on the j bar individual path is reserved.
Step 103: for i=n to 1:
After PCE (i) calculates and produces VSPT (i), VSPT (i) is checked, if having leaf node among the VSPT (i) is the node in non-this territory, then the individual path of leaf node on VSPT (i) in non-this territory taken back to PCE (i+1) by the PCEP agreement, with notice PCE (i+1) the reservation resource on this individual path is discharged, the branch that PCE (i) is corresponding with this leaf node simultaneously sends to PCE (i-1) from VSPT (i) deletion with the VSPT (i) that deletes correlated branch.Wherein, do not have the node of child node (namely degree is 0) in the middle of the one tree, be called leaf node, be called for short on " leaf ".Leaf degree of referring to is 0 node, is called again terminal node.
Further specify the present invention below by specific embodiment.
Embodiment one: the requirement of unmatchful resource utilization, the electricity layer calculates
Present embodiment has been described the BRPC computational process that unmatchful resource utilization requires in the computation requests.Provide the description of present embodiment specific implementation process below with reference to scene shown in Figure 2 (supposing that link is the electricity layer under this scene).
AS (i) and VSPT (i+1) have been provided among Fig. 2.DN is destination node, BN-en (1, i+1), BN-en (2, i+1) and BN-en (3, i+1) leaf node for VSPT (i+1) is the entry border node of AS (i+1), BN-en (1, i), BN-en (2, i) and BN-en (3, i) be the entry border node of AS (i), BN-ex (1, i) and BN-ex (2, i) be the outlet boundary node of AS (i).Need to set up now the shortest path tree of (i) entry border node from DN to AS, form VSPT (i), in conjunction with BRPC algorithm and the inventive method, computational process is as follows:
(1) PCE (i) checks the territory sequence, finds that this territory is intermediate field.The inspection path computing request is found the requirement of unmatchful resource utilization, PCE (i) calculates entry border node from AS (i) by general BRPC algorithm, and (BN-en (1, i), BN-en (2, i) and BN-en (3, i)) (BN-en (1 to the entry border node of AS (i+1), i+1), BN-en (2, i+1) and the bidirectional LSP path of BN-en (3, i+1)) (result of calculation as shown in Figure 3).Wherein entry border node BN-en (1, i), BN-en (2, i) and BN-en (3, i) corresponding LSP is respectively:
LSP(1)：BN-en(1，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)、
LSP(2)：BN-en(2，i)-R2-R3-BN-ex(1，i)-BN-en(2，i+1)、
LSP(3)：BN-en(3，i)-R1-BN-ex(2，i)-BN-en(3，i+1)。
(2) PCE (i) carries out resource reservation to the bidirectional LSP path that calculates.PCE (i) at first carries out resource reservation to path LSP (1), when then path LSP (2) being carried out resource reservation, first path LSP (2) and LSP (1) is compared, and judges whether two paths exist the coincidence path.Route segment R2-R3-BN-ex in the present embodiment (1, be to overlap the path i), and be electricity layer path.PCE (i) only carries out for non-coincidence route segment during to LSP (2) resource reservation, no longer route segment R2-R3 reserved, but the electricity layer resource (time slot) of having reserved among the multiplexing LSP (1).PCE (i) carries out electricity layer resource reservation to LSP (3), is compared with LSP (1) and LSP (2) respectively in the path of LSP (3), judges whether to exist to overlap the path, and this scene then need not multiplexing operation without overlapping the path;
(3) PCE (i) checks VSPT (i), find that leaf node is this territory and enters boundary node, need not VSPT (i) is deleted, simultaneously newly-generated VSPT (i) (as shown in Figure 4) is sent to forward PCE (i-1).
Embodiment two: the requirement of pair resource utilization is arranged, and the electricity layer calculates
Present embodiment has been described the BRPC computational process that has pair resource utilization to require in the path computing request.Provide the description of present embodiment specific implementation process below with reference to scene shown in Figure 2 (supposing that link is the electricity layer under this scene).
AS (i) and VSPT (i+1) have been provided among Fig. 2.DN is destination node, BN-en (1, i+1), BN-en (2, i+1) and BN-en (3, i+1) leaf node for VSPT (i+1) is the entry border node of AS (i+1), BN-en (1, i), BN-en (2, i) and BN-en (3, i) be the entry border node of AS (i), BN-ex (1, i) and BN-ex (2, i) be the outlet boundary node of AS (i).Need to set up now the shortest path tree of (i) entry border node from DN to AS, form VSPT (i), in conjunction with BRPC algorithm and the inventive method, computational process is as follows:
(1) PCE (i) checks the territory sequence, finds that this territory is intermediate field.Check that the computation requests discovery has the requirement of pair resource utilization, PCE (i) calculates entry border node from AS (i), and (BN-en (1, i), BN-en (2, i) and BN-en (3, i)) (BN-en (1 to the entry border node of AS (i+1), i+1), BN-en (2, i+1) and the bidirectional LSP path of BN-en (3, i+1)) guarantee that three LSP overlap (result of calculation as shown in Figure 5) as far as possible.Wherein entry border node BN-en (1, i), BN-en (2, i) and BN-en (3, i) corresponding LSP is respectively:
LSP(1)：BN-en(1，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)、
LSP(2)：BN-en(2，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)、
LSP(3)：BN-en(3，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)。
(2) PCE (i) carries out resource reservation to the bidirectional LSP path that calculates.
PCE (i) at first carries out resource reservation to path LSP (1);
When then path LSP (2) being carried out resource reservation, first path LSP (2) and LSP (1) are compared, judge whether two paths exist the coincidence path.In this embodiment route segment R2-R3-BN-ex (1, i) and domain-to-domain link BN-ex (1, i)-BN-en (1, be to overlap the path i+1), and be electricity layer resource.When reserving LSP (2) electricity layer resource (time slot), PCE (i) only carries out for non-coincidence route segment, no longer to route segment R2-R3-BN-ex (1, i) and domain-to-domain link BN-ex (1, i)-BN-en (1, i+1) reserve, but the resource of having reserved among the multiplexing LSP (1).
PCE (i) carries out resource reservation to LSP (3), compared with LSP (1) and LSP (2) respectively in the path of LSP (3), judge whether to exist to overlap route segment, to overlapping the resource of route segment fractional reuse LSP (1) and LSP (2);
(3) PCE (i) checks as shown in Figure 6 VSPT (i), find leaf node BN-en (2, i+1), BN-en (3, i+1) be non-domain node, with Node B N-en (2, i+1) and BN-en (2, i+1) (be ERO:BN-en (2 in branch's route corresponding to VSPT (i) by the ERO sequence, i+1)-...-...-DN and BN-en (3, i+1)-...-...-DN) be carried at and send to PCE (i+1) notice in the PCEP message and discharge corresponding reservation resource; Certainly, also can adopt other modes, by other message with BN-en (2, i+1) and BN-en (2, i+1) send to PCE (i+1) in branch's route corresponding to VSPT (i).
(4) corresponding node BN-en among PCE (i) the deletion VSPT (i) (2, i+1) and BN-en (3, branch i+1) sends to forward PCE (i-1) with newly-generated VSPT (i) (as shown in Figure 7).
Embodiment three: have pair resource utilization requirement, photosphere to calculate
Present embodiment has been described the BRPC computational process that has pair resource utilization to require in the computation requests.Provide the description of present embodiment specific implementation process below with reference to scene shown in Figure 2 (supposing that link is photosphere under this scene).
AS (i) and VSPT (i+1) have been provided among Fig. 2.DN is destination node, BN-en (1, i+1), BN-en (2, i+1) and BN-en (3, i+1) leaf node for VSPT (i+1) is the entry border node of AS (i+1), BN-en (1, i), BN-en (2, i) and BN-en (3, i) be the entry border node of AS (i), BN-ex (1, i) and BN-ex (2, i) be the outlet boundary node of AS (i).Need to set up now the shortest path tree of (i) entry border node from DN to AS, form VSPT (i), in conjunction with BRPC algorithm and the inventive method, computational process is as follows:
(1) PCE (i) checks the territory sequence, finds that this territory is intermediate field.Check that the computation requests discovery has the requirement of pair resource utilization, PCE (i) calculates entry border node from AS (i), and (BN-en (1, i), BN-en (2, i) and BN-en (3, i)) (BN-en (1 to the entry border node of AS (i+1), i+1), BN-en (2, i+1) and the bidirectional LSP path of BN-en (3, i+1)) guarantee that three LSP overlap (result of calculation as shown in Figure 8) as far as possible.Wherein entry border node BN-en (1, i), BN-en (2, i) and BN-en (3, i) corresponding LSP is respectively:
LSP(1)：BN-en(1，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)、
LSP(2)：BN-en(2，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)、
LSP(3)：BN-en(3，i)-R2-R3-BN-ex(1，i)-BN-en(1，i+1)。
(2) PCE (i) carries out resource reservation to the bidirectional LSP path that calculates.
PCE (i) at first carries out resource reservation to path LSP (1);
When then path LSP (2) being carried out resource reservation, first path LSP (2) and LSP (1) are compared, judge whether two paths exist the coincidence route segment.Route segment R2-R3-BN-ex in this use-case (1, i) and domain-to-domain link BN-ex (1, i)-BN-en (1, be to overlap route segment, and be the photosphere resource i+1).Only carry out for non-coincidence route segment when PCE (i) reserves the outside photosphere link circuit resource of LSP (2) (wavelength), no longer to route segment R2-R3-BN-ex (1, i) carry out.Further, whether the resource that overlaps intra-node (such as optical-electrical converter etc.) is overlapped and also judge, the resource of multiplexing LSP (1) of trying one's best (such as optical-electrical converter etc.), carry out no longer in addition resource reservation.
PCE (i) carries out resource reservation to LSP (3), compared with LSP (1) and LSP (2) respectively in the path of LSP (3), judge whether to exist to overlap route segment, to overlapping the resource of the multiplexing LSP of route segment (1) and LSP (2);
(3) PCE (i) checks VSPT shown in Figure 9 (i), find leaf node BN-en (2, i+1), BN-en (3, i+1) be non-domain node, with Node B N-en (2, i+1) and BN-en (2, i+1) (be ERO:BN-en (2 in branch's route corresponding to VSPT (i) by the ERO sequence, i+1)-...-...-DN and BN-en (3, i+1)-...-...-DN) be carried at and send to PCE (i+1) notice in the PCEP message and discharge corresponding reservation resource;
(4) corresponding node BN-en among PCE (i) the deletion VSPT (i) (2, i+1) and BN-en (3, branch i+1) sends to forward PCE (i-1) with newly-generated VSPT (i) (as shown in figure 10).
The embodiment of the invention also provides a kind of route calculation element, as shown in figure 11, comprising:
The path determination module is used for determining that the current field is to the bidirectional label exchange path of its adjacent domains;
The resource reservation module is used to described bidirectional label exchange path to carry out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence is carried out resource multiplex.
In a kind of alternative of present embodiment, described resource reservation module is carried out resource multiplex to the route segment of each coincidence and is comprised:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
In a kind of alternative of present embodiment, described resource reservation module is carried out resource multiplex to the route segment of each coincidence and is comprised:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
In this alternative, described resource reservation module also is used for: if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
In a kind of alternative of present embodiment, described path determination module also is used for:
When determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, pre-conditioned if path constraint satisfies, select the maximum bidirectional label exchange path of route segment that overlaps each other.
Described pre-conditioned comprising: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
In a kind of alternative of present embodiment, described device also comprises: the path transmission module, wherein:
Described path determination module determines that described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
Described path determination module also is used for, and when described the current field is when not comprising the territory of described source node, determines described the current field behind the bidirectional label exchange path in its next territory, the generating virtual shortest path tree;
Described path transmission module is used for, when described the current field is when not comprising the territory of described source node, whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
In this alternative, described path transmission module also is used for, when described the current field is when not comprising the territory of described destination node, branch's route that the leaf node of non-described the current field in the described virtual shortest path tree is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
The present invention also provides a kind of equipment that comprises above-mentioned route calculation element, and this equipment can be PCE.
The described scheme of the application can be applied to existing employing BRPC algorithm and calculate in the scheme of cross-domain LSP route, but is not limited to the BRPC algorithm, when carrying out the LSP route by other algorithms, also can use the application.
One of ordinary skill in the art will appreciate that all or part of step in the said method can come the instruction related hardware to finish by program, described program can be stored in the computer-readable recording medium, such as read-only memory, disk or CD etc.Alternatively, all or part of step of above-described embodiment also can realize with one or more integrated circuits.Correspondingly, each the module/unit in above-described embodiment can adopt the form of hardware to realize, also can adopt the form of software function module to realize.The present invention is not restricted to the combination of the hardware and software of any particular form.
Certainly; the present invention also can have other various embodiments; in the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make according to the present invention various corresponding changes and distortion, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.
Claims (16)
1. a route computing method is applied to source node in the route calculating of destination node, and source node comprises a plurality of territories to destination node, it is characterized in that, comprising:
The path-calculating element of the current field determines that described the current field is to the bidirectional label exchange path of its adjacent domains;
For described bidirectional label exchange path carries out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence carried out resource multiplex.
2. the method for claim 1 is characterized in that, described route segment to each coincidence carries out resource multiplex and comprises:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
3. the method for claim 1 is characterized in that, described route segment to each coincidence carries out resource multiplex and comprises:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
4. method as claimed in claim 3, it is characterized in that, described method also comprises: if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
5. the method for claim 1 is characterized in that, described method also comprises:
When determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, pre-conditioned if path constraint satisfies, select to overlap each other the maximum bidirectional label exchange path of route segment.
6. method as claimed in claim 5 is characterized in that, described pre-conditioned comprising: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
7. the method for claim 1 is characterized in that,
Determine that described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
When described the current field is that described method also comprises when not comprising the territory of described source node:
Determine described the current field behind the bidirectional label exchange path of its adjacent domains, the generating virtual shortest path tree;
Whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
8. method as claimed in claim 7, it is characterized in that, described method also comprises: described the current field is when not comprising the territory of described destination node, branch's route that the leaf node of non-described the current field is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
9. a route calculation element is characterized in that, comprising:
The path determination module is used for determining that the current field is to the bidirectional label exchange path of its adjacent domains;
The resource reservation module is used to described bidirectional label exchange path to carry out resource reservation, wherein, if there is the route segment that overlaps in each bidirectional label exchange path, then the route segment of each coincidence is carried out resource multiplex.
10. device as claimed in claim 9 is characterized in that, described resource reservation module is carried out resource multiplex to the route segment of each coincidence and comprised:
If the resource of reserving is electricity layer resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, then multiplexing has been the time interval resource of the route segment reservation of this coincidence.
11. device as claimed in claim 9 is characterized in that, described resource reservation module is carried out resource multiplex to the route segment of each coincidence and is comprised:
If the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and carry out the route segment that the bidirectional label exchange path of resource reservation exist to overlap, then multiplexing be the wavelength resource of outside photosphere link of the route segment reservation of this coincidence.
12. device as claimed in claim 11, it is characterized in that, described resource reservation module also is used for: if the resource of reserving is the photosphere resource, when carrying out resource reservation for current bidirectional label exchange path, if current bidirectional label exchange path and the route segment that carries out the bidirectional label exchange path existence coincidence of resource reservation, the resource of the intra-node on the route segment of multiplexing described coincidence.
13. device as claimed in claim 9 is characterized in that, described path determination module also is used for:
When determining that described the current field arrives the bidirectional label exchange path of its adjacent domains, pre-conditioned if path constraint satisfies, select the maximum bidirectional label exchange path of route segment that overlaps each other.
14. device as claimed in claim 13 is characterized in that, described pre-conditioned comprising: the available resources that resource utilization is required to be higher than the requirement of path optimality and/or described the current field are lower than resource threshold.
15. device as claimed in claim 9 is characterized in that, described device also comprises: the path transmission module, wherein:
Described path determination module determines that described the current field to the bidirectional label exchange path of its adjacent domains is: determine described the current field to the bidirectional label exchange path in its next territory, described next territory is the territory of adjacent with described the current field and close described destination node;
Described path determination module also is used for, and when described the current field is when not comprising the territory of described source node, determines described the current field behind the bidirectional label exchange path in its next territory, the generating virtual shortest path tree;
Described path transmission module is used for, when described the current field is when not comprising the territory of described source node, whether the leaf node of judging described virtual shortest path tree is the node of described the current field, if not, after deleting the branch of the leaf node of non-the current field described in the described virtual shortest path tree, described virtual shortest path tree is sent to the path-calculating element in the last territory of described the current field; The last territory of described the current field is the territory of adjacent with described the current field and close described source node.
16. device as claimed in claim 15 is characterized in that,
Described path transmission module also is used for, when described the current field is when not comprising the territory of described destination node, branch's route that the leaf node of non-described the current field in the described virtual shortest path tree is corresponding sends to the path-calculating element in next territory of described the current field, so that the path-calculating element in described next territory discharges reservation resource corresponding to described branch route.
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