CN102469008A - Method for automatically triggering creation of hierarchical label switched path and system - Google Patents
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Abstract
The invention discloses a method for automatically triggering creation of a hierarchical label switched path (LSP). The method comprises the following steps: under a multi-layer multi-domain scene, in a LSP calculation result returned to a label switched router (LSR), a path computation element (PCE) carries a complete path and switched layer information of interfaces along the path; the LSR carries the complete path and the switched layer information in a resource reservation protocol (RSVP) signal of establishing the LSP; the LSR passed by the RSVP signal determines a start point and a terminal point of a lower layer LSP boundary, thus automatically triggering creation of a lower layer LSP is realized. The invention discloses a system for automatically triggering creation of the hierarchical label switched path simultaneously. Through a scheme of the present invention, automatically triggering creation of the lower layer LSP can be realized.
Description
Technical Field
The invention relates to a technology for establishing a label switched path under a multilayer multi-domain, in particular to a method and a system for automatically triggering and establishing a hierarchical Label Switched Path (LSP).
Background
MPLS and GMPLS networks may contain both multiple domains (domains) and layers (layers). Domain refers to a set of network elements divided for managing common addresses or for path computation. Where both the Autonomous System (AS) and the area (IGP area) are domains. An AS is a collection of routers that exchange routing information with each other via a common routing protocol. IGP Area is an Area where one IGP algorithm is operated alone. Topology information within an Area is not visible outside the Area, nor is the detailed topology information outside the Area known to an internal router of a given Area.
In a GMPLS network, the IETF distinguishes networks composed of nodes with different switching technologies by areas (REGIONs), such as IP over SDH, SDH over WDM, IP over WDM, and then networks composed of IP, SDH, and WDM nodes are different REGIONs, respectively. Domain, a switching capability, determines a REGION, and networks containing multiple switching capabilities are called multi-REGION networks (MRNs). On the other hand, in the hierarchical network, a network including one REGION is one layer, and a network including a plurality of REGIONs is called a multi-layer network (MLN). Thus, multiple layers and multiple domains are linked together, and a multi-domain network is also a multi-layer network.
Path Computation Element (PCE) refers to: entities that use constraints to compute a network path or route based on the network topology. The PCE may be located on a network node or may be a server outside the network, etc. The PCE may compute traffic engineering based label switched paths (TE LSPs) by bandwidth and other constraints by accessing a Traffic Engineering Database (TED).
Employing PCEs in a multi-layer network is a powerful tool to obtain a flow that spans multiple layers, and PCEs can implement global optimization rather than path optimization at a single network level. In MPLS and GMPLS based networks, PCE provides a solution inter-layer path computation framework, which is described in IETF RFC5623, and proposes two inter-layer computation models for multi-layer networks, including a single PCE inter-layer path computation model and a multi-PCE inter-layer path computation model.
For example: the upper level network in FIG. 1 is a packet-switched based IP/MPLS network consisting of Label Switched Routers (LSR) H1, H2, H3, and H4; the underlying network is a GMPLS optical network consisting of LSRs H2, L1, L2, and H3. Assume that there is no TE link between upper layer boundaries H2 and H3. H1 of the upper network needs to establish an LSP to go to H4.
In the single-PCE inter-layer path computation model, the PCE is a multi-layer PCE, and the topology of the upper layer and the lower layer can be seen, so that the PCE can perform end-to-end path computation for traversing the lower layer.
In the multi-PCE inter-layer path computation model, there is at least one PCE per layer, and each PCE sees only the topology of the layer. Such as: in fig. 1, if a single layer path computation is performed in the upper layer, it will fail due to the lack of TE link, but if an inter-layer path computation is used, a route H1-H2-H3-H4 can be provided in the upper layer, and it is proposed to establish a lower layer LSP H2-L1-L2-H3 at the border router. It can be seen that the cooperation of the PCEs of each layer is needed to compute the end-to-end optimal path across multiple layers.
The draft-ietf-pce-inter-layer-ext expands the PCEP protocol defined in the RFC5440, and the expanded PCEP can support inter-layer path calculation. This draft has mainly expanded three objects: an INTER-LAYER object, which may be used to indicate whether INTER-LAYER path computation and trigger signaling is allowed in a path computation request (PCReq) message of the PCEP protocol; a SWITCH-LAYER object, usable in PCReq to indicate the switching LAYER through which an LSP must or must not pass; the REQ-ADAP-CAP object may be used in the computation request message PCReq to specify the adaptation capability requested by the lower LSP two-endpoints. In this draft, the INTER-LAYER object, SWITCH-LAYER object, and REQ-ADAP-CAP object are all carried only when PATH computation fails, i.e., the INTER-LAYER object, SWITCH-LAYER object, and REQ-ADAP-CAP object together with the NO-PATH object respectively represent unsatisfiable constraints in a PATH computation reply (PCRep) message. And when the path calculation is successful, the INTER-LAYER object, the SWITCH-LAYER object and the REQ-ADAP-CAP object are not carried in the PCRep message, so that the information related to the switching LAYER of the node through which the result path passes cannot be calculated.
In a single layer network, REQ-ADAP-CAP objects may also be used in PCReq to specify the adaptation capabilities of both end points of an LSP. In this case, it is not necessary to use with INTER-LAYER objects.
No matter which PCE model is adopted, the final PCE can calculate an end-to-end complete path H1-H2-L1-L2-H3-H4 spanning multiple layers, and returns to H1, then creates an end-to-end LSP using resource reservation Protocol (RSVP) signaling, if the lower layer LSP H2-L1-L2-H3 is not created, the creation of the lower layer LSP needs to be triggered automatically in the signaling process, i.e. the PATH message of RSVP is sent from LSR H1 to H2 along the complete end-to-end PATH (H1-H2-L1-L2-H3-H4), h2 needs to be able to recognize that the start point of the lower layer LSP is itself, and to recognize that the end point is H3, and then temporarily blocking the PATH message from being transmitted downstream, triggering the creation of the lower layer LSP from H2 to H3, awakening the establishment of the upper layer connection after the lower layer LSP is successfully created, and continuing the establishment process of the connection.
IETF RFC4206 describes a method for determining a starting point and an end point of a lower layer LSP, that is, a REGION boundary, that is, when interface switching capabilities of interfaces at two ends of a TE link change, the REGION boundary is represented, for example, if the interface switching capability of a right side interface of LSR H2 is less than the interface switching capability of a left side interface of LSR L1, a new REGION is represented, and H2 is the REGION boundary, that is, the starting point of the lower layer LSP; the interface switching capability of the interface on the right side of LSR L2 > the interface switching capability of the interface on the left side of LSR H4 indicates exit from a REGION, and H4 is the REGION boundary, i.e., the end point of the lower layer LSP.
According to the method for determining the starting point and the ending point of the lower layer LSP described in IETF RFC4206, the boundary determination of the lower layer LSP requires to know the interface switching capability of each interface along the LSP path, but no method for carrying such information is given in the current PCEP protocol and RSVP protocol, so the boundary of the lower layer LSP cannot be determined, and thus the creation of the lower layer LSP cannot be automatically triggered.
Disclosure of Invention
In view of this, the main objective of the present invention is to provide a method and a system for automatically triggering and creating a hierarchical label switched path, so as to implement the creation of an LSP at a lower layer.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
the invention provides a method for realizing automatic triggering and establishing a hierarchical label switched path, which comprises the following steps:
PCE carries complete path and exchange layer information of path passing through interface along the way in LSP path calculation result returned to LSR;
the LSR carries the complete path and exchange layer information in the RSVP signaling for establishing the LSP;
and the LSR through which the RSVP signaling passes determines the starting point and the end point of the lower layer LSP boundary, and triggers the automatic creation of the lower layer LSP according to the lower layer LSP boundary.
In the above solution, the LSP path computation result returned by the PCE to the LSR carries complete path and exchange layer information of the path passing through the interface along the way, and is: after receiving the path computation request sent by the LSR, the PCE performs LSP path computation to obtain an end-to-end route traversing multiple layers, and carries the complete path in the path computation result and the exchange layer information of the path passing through the interface along the path by the PCRep returned to the LSR.
In the above scheme, the method further comprises: and the PCRep carries exchange layer information in an attribute table of the message body.
In the above scheme, the exchange LAYER information includes an INTER-LAYER object and a SWITCH-LAYER object, where the SWITCH-LAYER object carries an exchange type, an encoding type, and an exchange granularity of an interface, where the exchange type is an exchange capability; the INTER-LAYER object is used to indicate whether a path is an INTER-LAYER path.
In the above solution, the RSVP signaling for establishing the LSP, which carries the complete path and exchange layer information, includes: an Explicit Routing Object (ERO) object and a Switching Type of a sub-object of the ERO object are carried in RSVP signaling for establishing an LSP, the Switching Type field is added with an exchange Type, an encoding Type and an exchange granularity of interfaces passing along a path, and the complete path is carried by the ERO object.
In the above solution, the determining the start point and the end point of the lower layer LSP boundary includes: each LSR through which the RSVP signaling passes compares the exchange capability and the exchange granularity of an interface of the LSR with the next LSR interface according to the complete path and exchange layer information carried by the RSVP signaling, when the exchange capability or the exchange granularity of the current LSR interface is smaller than the exchange capability or the exchange granularity of the next LSR interface, the current LSR interface is used as the starting point of the lower LSP, an ERO object in the RSVP signaling and a child object Switching Type of the ERO object are traversed, and the first LSR interface with the same exchange capability and the same exchange granularity as the current LSR interface is searched in the interfaces passing along as the end point of the lower LSP.
The invention provides a system for automatically triggering and creating a hierarchical label switched path, which comprises: PCE, LSR in the multi-domain network; wherein,
PCE, use for carry complete route and route along exchange layer information of the interface in LSP route calculation result that return to LSR;
LSR, which is used to carry the said complete path and exchange layer information in RSVP signaling for establishing LSP, to determine the starting point and end point of the lower layer LSP boundary, and to trigger the automatic establishment of the lower layer LSP according to the lower layer LSP boundary.
In the above scheme, the PCE is specifically configured to perform LSP path computation after receiving a path computation request sent by the LSR, including performing inter-layer path computation to obtain an end-to-end route traversing multiple layers, and carrying complete paths in a path computation result and exchange layer information of the paths passing through interfaces along the path by a PCRep returned to the LSR.
In the foregoing solution, the LSR is specifically configured to carry an ERO object and a Switching Type of a sub-object of the ERO object in an RSVP signaling for establishing an LSP, where the Switching Type field is added with an exchange Type, an encoding Type, and an exchange granularity of an interface that a path passes along, and the complete path is carried by the ERO object.
In the foregoing solution, the LSR is further configured to compare, according to the complete path and exchange layer information carried by the RSVP signaling, the exchange capability and the exchange granularity of the interface of the LSR with those of the next interface of the LSR, determine that the interface of the LSR is used as the lower LSP starting point when the exchange capability or the exchange granularity of the interface of the LSR is smaller than that of the next interface of the LSR, traverse the ERO object in the RSVP signaling and the Switching Type of the sub-object of the ERO object, and find the first interface of the LSR having the same exchange capability and the same exchange granularity as those of the interface of the LSR in the interface passing along as the lower LSP ending point.
In the method and the system for automatically triggering and establishing the hierarchical label switched path, under a multilayer multi-domain scene, a PCE carries complete path and switching layer information of interfaces along the path in an LSP path calculation result returned to an LSR; the LSR carries the complete path and exchange layer information in the RSVP signaling for establishing the LSP, and the LSR through which the RSVP signaling passes determines the starting point and the end point of the boundary of the lower layer LSP so as to realize the automatic triggering of the establishment of the lower layer LSP; therefore, the method can realize the automatic triggering of the establishment of the lower layer LSP in a multi-protocol label switching (MPLS) or general multi-protocol label switching (GMPLS) network comprising multiple domains.
Drawings
FIG. 1 is a schematic diagram of a two-layer network of prior art packet-switched based IP/MPLS and GMPLS networks;
FIG. 2 is a flow chart illustrating a method for implementing automatic triggering of creation of a hierarchical label switched path according to the present invention;
FIG. 3 is a schematic diagram of a network used in accordance with an embodiment of the present invention;
FIG. 4 is a schematic diagram of a network used in the second embodiment of the present invention;
fig. 5 is a schematic structural diagram of a system for implementing automatic triggering of creating a hierarchical label switched path according to the present invention.
Detailed Description
The basic idea of the invention is: under the multilayer multi-domain scene, PCE carries complete path and exchange layer information of the path passing through the interface along the way in the LSP path calculation result returned to LSR; the LSR carries the complete path and exchange layer information in the RSVP signaling for establishing the LSP, and the LSR passed by the RSVP signaling determines the starting point and the end point of the boundary of the lower layer LSP, thereby realizing the automatic triggering of the establishment of the lower layer LSP.
The invention is further described in detail below with reference to the figures and the specific embodiments.
The invention realizes a method for automatically triggering and creating a hierarchical label switched path, as shown in fig. 2, the method comprises the following steps:
step 201: PCE carries complete path and exchange layer information of path passing through interface in LSP path calculation result returned to LSR;
specifically, in an MPLS or GMPLS network including multiple domains, after receiving a path computation request sent by an LSR, a PCE performs LSP path computation, including performing inter-layer path computation to obtain an end-to-end route traversing multiple layers, and carries a complete path in a path computation result and exchange layer information of interfaces along the path by a PCRep returned to the LSR; the exchange LAYER information comprises an INTER-LAYER object and a SWITCH-LAYER object, wherein the SWITCH-LAYER object carries the exchange type, the coding type and the exchange granularity of an interface, and the exchange type is the exchange capability; the INTER-LAYER object is used for indicating whether the path is an INTER-LAYER path or not; the PCRep carries exchange layer information in an attribute-list (attribute-list) of the message body, for example:
<PCRep Message>::＝<Common Header>
<response-list>
wherein:
<response-list>::＝<response>[<response-list>]
<response>::＝<RP>
[<NO-PATH>]
[<attribute-list>]
[<path-list>]
<path-list>::＝<path>[<path-list>]
<path>::＝<ERO><attribute-list>
wherein:
<attribute-list>::＝[<OF>]
[<LSPA>]
[<BANDWIDTH>]
[<metric-list>]
[<IRO>]
[<INTER-LAYER>]
[<SWITCH-LAYER>]
[<REQ-ADAP-CAP>]
<metric-list>::＝<METRIC>[<metric-list>]
as can be seen, the attribute-list contains the INTER-LAYER object and the SWITCH-LAYER object;
the format of the INTER-LAYER object in draft-ietf-pce-INTER-LAYER-ext is shown in the following table:
wherein, flag bit (flag) I (1 bit): the PCE uses the I flag to indicate in the computation result message PCRep whether the returned path is an inter-layer path. When the I mark is 1, the returned path is an interlayer path; when the I flag is 0, it indicates that the returned path is a single-layer path.
Flag bit T (1 bit): the PCE uses the T-flag in the computation result message PCRep to indicate whether the LSR needs to trigger signaling to support the returned path. When the T mark is set to be 1, signaling needs to be triggered; when the T flag is set to 0, it indicates that no trigger signaling is required.
The format of the SWITCH-LAYER object is shown in the following table:
the LSP enc.type and Switching Type together indicate that a specified coding Type and Switching Type must be used or prohibited to be used when calculating a path.
The Traffic Parameters object is used to indicate the switching granularity of the service layer LSP, and the format is related to the service layer technology, and has been defined in each technical standard. For example, for SDH and SONET, the definition of this parameter is defined in RFC4606, including information of signal type, concatenation type and number.
Flag bit I (1 bit): when the I mark is 1, the calculated path is indicated to pass through a layer corresponding to the specified exchange type and the coding type; when the I flag is 0, it indicates that the calculated path can never enter or pass through the layer corresponding to the specified switch type and encoding type. If the LSR only needs to specify the SwitchingType but not the LSP Enc.Type, set LSP Enc.Type to 0.
Step 202: the LSR receives the calculation result of the LSP path, and the RSVP signaling for establishing the LSP carries the complete path and exchange layer information;
in this step, the RSVP signaling for establishing the LSP carries the complete PATH and exchange layer information, generally, the RSVP signaling for establishing the LSP carries an ERO object and a Switching Type of a sub-object extended by the ERO object, the Switching Type field is added with an exchange Type, an encoding Type, and an exchange granularity of an interface that a PATH passes along, the complete PATH is carried by the ERO object, and the RSVP signaling for establishing the LSP is generally a PATH message.
Step 203: the LSR through which the RSVP signaling passes determines the starting point and the end point of the lower layer LSP boundary according to the method for judging the REGION boundary, and triggers the automatic establishment of the lower layer LSP according to the boundary of the lower layer LSP;
specifically, each LSR through which the RSVP signaling passes compares the Switching capability and Switching granularity of its own interface with the next LSR interface according to the complete path and Switching layer information carried by the RSVP signaling, and when the Switching capability or Switching granularity of the current LSR interface is smaller than that of the next LSR interface, the current LSR interface serves as the lower layer LSP starting point, traverses the ERO object in the RSVP signaling and the Switching Type of the sub-object extended by the ERO object, and finds the first LSR interface with the same Switching capability and Switching granularity as the current LSR interface in the interfaces passing along as the lower layer LSP terminating point; after the boundary of the lower layer LSP is determined, namely the starting point and the end point of the lower layer LSP are determined, the LSR of the LSR interface as the starting point of the lower layer LSP triggers the automatic establishment of the lower layer LSP according to the boundary of the lower layer LSP;
specific examples of this step are as follows:
example one: in this example, as shown in fig. 3, the network includes two layers, H1, H2, H3, and H4 are upper layer LSRs, H2, L1, L2, and H3 are lower layer LSRs, H1 is connected to an a interface of H2 through an a interface, H2 is connected to an a interface of L1 through a b interface, a interface of L1 is connected to a b interface of L2, an a interface of L2 is connected to a interface of H3, and an a interface of H3 is connected to an a interface of H4, where all interfaces of H1, H2, H3, and H4 have PSC and the same switching granularity, and all interfaces of L1 and L2 have TDM and the same switching granularity. The RSVP signaling is specifically a PATH message, where the ERO object carried by the PATH message and the Switching Type of the sub-object extended by the ERO object are: { H1a, PSC, H2a, PSC, H2b, PSC, L1a, TDM, L1b, TDM, L2b, TDM, L2a, TDM, H3b, PSC, H3a, PSC, H4a, PSC }. After the H1 receives the PATH message, analyzing the ERO object and the Switching Type carried in the PATH message, and comparing the Switching capabilities and the Switching granularities of H1a and H2a, wherein the Switching capabilities are PSCs and the Switching granularities are the same, so that the PATH message is continuously transmitted downstream; when H2 receives the PATH message, the switching capability and the switching granularity of H2b are compared with the switching capability and the switching granularity of the next node L1a, at this time, the switching capability PSC of H2b is less than the switching capability TDM of L1a, and H2b is determined as the starting point of the lower layer LSP; then, H2 traverses the ERO object and the SwitchingType, finds that the interface with the first switching capability of PSC in the subsequent ERO object is H3b, and the switching granularity of H3b is the same as that of H2b, then H3b is the end point of the lower layer LSP, that is: the switching capacity L1 a-L1 b-L2 b-L2 a of the search interface is TDM, the switching capacity of H3b is the switching capacity of PSC-starting point H2b, the switching granularity of H3b is the same as H2b, and PSC < TDM, so H3b is the end point of the lower layer LSP. Thereafter, H2 triggers the automatic establishment of the lower layer LSP according to the boundaries H2b and H3b of the lower layer LSP.
Example two: in this example, as shown in fig. 4, the network includes three layers, which is the case of nested LSP establishment, where H1, H2, H3, and H4 are upper layer LSRs, M1 and M2 are lower layer LSRs, and L1 and L2 are lower layer LSRs. After H2 receives the PATH message, comparing the exchange capability and the exchange granularity of H2b and the next node M1a, and when the exchange capability of H2b is less than that of M1a, determining that H2b is the starting point of the lower layer LSP; then, H2 traverses the ERO object and the Switching Type, finds that the interface with the first Switching capability and the same Switching granularity as H2b in the subsequent ERO object is H3b, and then H3b is the end point of the lower layer LSP, and then H2 triggers the automatic establishment of the lower layer LSP according to the boundaries H2b and H3b of the lower layer LSP, and at the same time the PATH message carries the ERO object and the Switching Type to continue to transfer. When the PATH message reaches M1, M1 compares the switching capability of M1b with that of L1a, but the switching granularity of M1b is less than that of L1a, it is determined that M1b is the lower layer LSP starting point, according to the above traversal method, because M2b is the first switching capability in the subsequent ERO sub-object and the switching granularity is the same as that of M1b, it is determined that M2b is the lower layer LSP ending point, and M1 then triggers the automatic creation of LSPs from lower layers M1b to M2 b.
In order to implement the above method, the present invention further provides a system for automatically triggering the creation of a hierarchical label switched path, as shown in fig. 5, the system includes: PCE 61, LSR 62 in a multi-domain network; wherein,
the PCE 61 is specifically configured to perform LSP path computation after receiving a path computation request sent by the LSR 62, including performing inter-layer path computation to obtain an end-to-end route traversing multiple layers, and carrying complete paths in a path computation result and exchange layer information of interfaces along the paths by a PCRep returned to the LSR 62; the exchange LAYER information comprises an INTER-LAYER object and a SWITCH-LAYER object, wherein the SWITCH-LAYER object carries the exchange type, the coding type and the exchange granularity of an interface, and the exchange type is the exchange capability; the INTER-LAYER object is used for indicating whether the path is an INTER-LAYER path; the PCRep carries an INTER-LAYER object and a SWITCH-LAYER object in an attribute table of a message body;
the LSR 62 carries the complete path and exchange layer information in the RSVP signaling for establishing the LSP, which specifically includes: the LSR 62 carries an ERO object and a Switching Type of the sub-object extended by the ERO object in RSVP signaling for establishing an LSP, adds an exchange Type, an encoding Type, and an exchange granularity of an interface passed along a path to a Switching Type field, and the complete path is carried by the ERO object;
the LSR 62 determines the starting point and the ending point of the lower layer LSP boundary according to the method for determining the REGION boundary, which specifically includes: the LSR 62 compares the Switching capacity and the Switching granularity of the interface with the next LSR interface according to the complete path and the Switching layer information carried by the RSVP signaling, determines the interface as the starting point of the lower layer LSP when the Switching capacity or the Switching granularity of the interface is smaller than that of the next LSR interface, traverses an ERO object in the RSVP signaling and a Switching Type of a sub-object expanded by the ERO object, and finds the first LSR interface with the same Switching capacity and the same Switching granularity as the interface as the lower layer LSP end point in the interfaces passing along the way;
the LSR 62 finds the end point of the boundary of the lower layer LSP, specifically, the LSR 62 traverses the ERO object in the RSVP signaling and the Switching Type of the sub-object extended by the ERO object, and finds the first LSR interface with the same Switching capability as the interface of the first LSR interface as the end point of the lower layer LSP from the interfaces passing along.
The method can realize the automatic triggering of the establishment of the lower layer LSP in the MPLS or GMPLS network containing multiple domains, only needs to slightly expand the prior draft-ietf-pc-inter-layer-ext protocol, and is simple and easy to realize.
The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, and any modifications, equivalents, improvements, etc. that are within the spirit and principle of the present invention should be included in the present invention.
Claims (10)
1. A method for realizing automatic triggering and establishing a hierarchical label switched path is characterized by comprising the following steps:
a Path Computation Element (PCE) carries complete path and exchange layer information of interfaces along the path in a Label Switching Path (LSP) path computation result returned to a Label Switching Router (LSR);
the LSR carries the complete path and exchange layer information in resource reservation protocol (RSVP) signaling for establishing LSP;
and the LSR through which the RSVP signaling passes determines the starting point and the end point of the lower layer LSP boundary, and triggers the automatic creation of the lower layer LSP according to the lower layer LSP boundary.
2. The method of claim 1, wherein the PCE carries complete path and switching layer information of the path along the way across the interface in the LSP path computation result returned to the LSR as: after receiving the path computation request sent by the LSR, the PCE performs LSP path computation to obtain an end-to-end route traversing multiple layers, and carries a complete path in the path computation result and exchange layer information of the path passing through the interface along the path by a path computation response (PCRep) returned to the LSR.
3. The method of claim 2, further comprising: and the PCRep carries exchange layer information in an attribute table of the message body.
4. The method according to any of claims 1 to 3, wherein the switching LAYER information comprises an INTER-LAYER object and a SWITCH-LAYER object, the SWITCH-LAYER object carries the switching type, the coding type and the switching granularity of the interface, the switching type is the switching capability; the INTER-LAYER object is used to indicate whether a path is an INTER-LAYER path.
5. The method of claim 4, wherein the complete path and switching layer information is carried in RSVP signaling for establishing the LSP by: an Explicit Routing Object (ERO) object and a Switching Type of a sub-object of the ERO object are carried in RSVP signaling for establishing an LSP, the Switching Type field is added with an exchange Type, an encoding Type and an exchange granularity of interfaces passing along a path, and the complete path is carried by the ERO object.
6. The method of claim 4, wherein determining the start and end points of the lower layer LSP boundary is: each LSR through which the RSVP signaling passes compares the exchange capability and the exchange granularity of an interface of the LSR with the next LSR interface according to the complete path and exchange layer information carried by the RSVP signaling, when the exchange capability or the exchange granularity of the current LSR interface is smaller than the exchange capability or the exchange granularity of the next LSR interface, the current LSR interface is used as the starting point of the lower LSP, an ERO object in the RSVP signaling and a child object Switching Type of the ERO object are traversed, and the first LSR interface with the same exchange capability and the same exchange granularity as the current LSR interface is searched in the interfaces passing along as the end point of the lower LSP.
7. A system for automatically triggering the creation of a hierarchical label switched path, the system comprising: PCE, LSR in the multi-domain network; wherein,
PCE, use for carry complete route and route along exchange layer information of the interface in LSP route calculation result that return to LSR;
LSR, which is used to carry the said complete path and exchange layer information in RSVP signaling for establishing LSP, to determine the starting point and end point of the lower layer LSP boundary, and to trigger the automatic establishment of the lower layer LSP according to the lower layer LSP boundary.
8. The system of claim 7, wherein the PCE is specifically configured to perform LSP path computation after receiving a path computation request sent by the LSR, including performing inter-layer path computation to obtain an end-to-end route traversing multiple layers, and carrying complete paths in the path computation result and exchange layer information of interfaces along the paths by PCRep returned to the LSR.
9. The system according to claim 7, wherein said LSR is specifically configured to carry an ERO object and a Switching Type of a sub-object of said ERO object in RSVP signaling for establishing an LSP, and add a Switching Type, an encoding Type, and a Switching granularity of an interface that a path passes along in a field of said Switching Type, and said complete path is carried by said ERO object.
10. The system of claim 9, wherein the LSR is further configured to compare the Switching capabilities and the Switching granularities of the self interface and the next LSR interface according to the complete path and Switching layer information carried in the RSVP signaling, determine the self interface as a lower layer LSP starting point when the Switching capabilities or the Switching granularities of the self interface are smaller than those of the next LSR interface, traverse the ERO object in the RSVP signaling and the Switching Type of the ERO object, and find the first LSR interface with the same Switching capabilities and the same Switching granularity as the self interface as a lower layer LSP terminating point in the interfaces passing along.
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