Method, device and system for creating sr policy using path computation element protocol

Abstract

The present invention provides a mechanism to support creation of SR policy using PCEP extensions. In one implementation, a PCE (130) communicates with a PCC (112) using PCEP mechanisms. The PCE (130) sends a first PCEP initialization message PCInitiate to the PCC (112), the first PCEP message carrying a central controller instruction with CC-ID = X for creating an SR policy. The PCC (112) receives the first PCEP initialization message from the PCE (130), creates the SR policy using SR policy parameters, the SR policy being a container independent of any candidate path. Further, the PCC (112) sends a first PCEP report message PCRpt to the PCE (130) to report confirmation of CC-ID = X and the newly created SR policy.

Description

[0001] This application claims priority to Indian Patent Application No. IN202031055293, entitled “SR Policy Instantiation via PCEP,” filed with the Indian Patent Office on December 18, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The invention described herein generally relates to networks enabled by Software Defined Networking (SDN). Specifically, embodiments described herein relate to systems, apparatus, and methods using the Path Computation Element Protocol (PCEP). Background Technology

[0003] Segment routing (SR) is a source routing technique that simplifies traffic engineering and management across network domains. It removes network state information from transport routers and nodes in the network and places path state information in the packet header of the ingress node. This means the ingress node can place the header before a packet containing a list of segments, which are instructions executed on subsequent nodes in the network. These instructions can be forwarding instructions, such as instructions to forward packets to a specific destination or interface. Segment routing can be implemented on MPLS or IPv6 networks. In SR-MPLS networks, segments are encoded as MPLS labels. In SRv6 networks, a new header called the Segment Routing Header (SRH) is used. Segments in the SRH are encoded in a list of IPv6 addresses.

[0004] A Path Computation Element (PCE) is an entity capable of calculating network paths or routes based on a network graph and applying computational constraints during the calculation. The PCE entity can be an application residing within a network node or component, on a server, etc. The PCE receives path calculation requests from a Path Computation Client (PCC), which requests the initiation of a path at the PCC. In response to the path calculation request, the PCE calculates the path from the PCC through intermediate nodes to the exit node and assigns label information to the label-switched paths (LSPs) from the PCC, intermediate nodes, and exit node. The PCE establishes LSPs along the calculated path by directly transmitting the label information to the PCC, intermediate nodes, and exit node for storage in the Forwarding Information Base (FIB).

[0005] The Path Computation Element Protocol (PCEP) defines the communication between the Path Computation Client (PCC) and the Path Computation Element (PCE), as well as the communication between PCEs, thus enabling the computation of Multiprotocol Label Switching (MPLS) with Traffic Engineering Label Switched Path (TE LSP) characteristics.

[0006] PCE is used to compute SR paths in SR networks. The Path Computation Element Protocol (PCEP) has been extended to support this protocol. For details, please refer to the Internet draft of the PCE working group entitled "PCEP Procedure and Protocol Extensions for Using PCE as a Central Controller (PCECC) of LSP". A PCE-based central controller (PCECC) simplifies the handling of the distributed control plane by integrating it with SDN elements, rather than necessarily replacing it entirely. PCECC enables PCE encoding of various Central Controller Instructions (CCIs) executed by the PCC.

[0007] SR policy is a framework that supports the instantiation of ordered lists of segments on nodes to enforce source routing policies for traffic routing from those nodes. SR policies can be constructed using any type of segment identifier (SID), including SIDs associated with topology or service instructions. An SR policy is associated with one or more candidate paths (CPs). A candidate path is a unit of SR policy signaling sent to the headend via protocols such as PCEP, and the SR policy is transmitted as part of a new association type encoded along with these candidate paths. For details, please refer to the Internet draft entitled "PCEP Extensions Supporting Candidate Paths for Segment Routing Policies" from the PCE working group.

[0008] In existing schemes using PCEP extensions to support segment routing (SR), it is not possible to create SR policies independent of candidate paths within PCEP. SR policies created within PCEP are always defined as a set of candidate paths. For example, an SR policy named "POL1" would look like this:

[0009] SR Strategy POL1 <Head, Color, Endpoint>

[0010] Candidate path CP1<protocol source=20, initiator=100:1.1.1.1, identifier=1>

[0011] Priority 200

[0012] Weight W1, SID-List1<SID11...SID1i>

[0013] Weight W2, SID-List2<SID21...SID2j>

[0014] Candidate path CP2<protocol source=20, initiator=100:2.2.2.2, identifier=2>

[0015] Priority 100

[0016] Weight W3, SID-List3<SID31...SID3i>

[0017] Weight W4, SID-List4<SID41...SID4j>

[0018] SR policies are identified by the <header, color, endpoint> tuple. The header is the node that instantiates / implements the policy. The header is specified as an IPv4 or IPv6 address and should be unique within the domain. The endpoint indicates the destination of the policy. The endpoint is specified as an IPv4 or IPv6 address and should be unique within the domain. The color is a 32-bit value that associates the SR policy with an intent (e.g., low latency, high bandwidth, etc.). The endpoint and color are used to automatically guide service or transport routes on the SR policy. The SR policy defined in the example above defines two candidate paths (CP1 and CP2), and the priority of the candidate paths can be used to select the best candidate path for the SR policy. Each candidate path (CP1 and CP2) is identified by the tuple <protocol source, initiator, identifier>. CP1 is the active candidate path (valid and highest priority). The two fragment lists of CP1 are installed as forwarding instantiations of SR policy POL1. For more details on defining the SR policy in the example above, please refer to the SPRING Working Group's Internet draft entitled "Fragmented Routing Policy Architecture".

[0019] The PCEP includes the following extensions; for details, please refer to the Internet draft "PCEP Extensions to Support Candidate Paths for Segmented Routing Policies":

[0020] New SR strategy association type

[0021] Each candidate path also includes public information such as color, endpoints (type, length, value) in the SR policy identifier TLV, and SR policy name.

[0022] Each candidate path also includes a single candidate path identifier (TLV) and path priority information.

[0023] SR strategy information is appended as associated information to each candidate path.

[0024] One drawback of always associating the creation of an SR policy with candidate paths is that if a candidate path fails in the network, the entire SR policy may become invalid, depending on the status of the other candidate paths associated with the SR policy. Currently, PCEP does not allow the creation of SR policies independent of candidate paths. SR policies are immutable container information and need to be encoded separately along with each candidate path. Summary of the Invention

[0025] This invention aims to introduce concepts related to instantiating segment routing (SR) strategies via the Path Communication Element Protocol (PCEP), as detailed below. This invention is not intended to identify key features of the claimed subject matter, nor is it intended to determine or limit the scope of the claimed subject matter.

[0026] The primary objective of this invention is to provide a mechanism for creating SR (Strategy Response) policies independent of candidate paths using PCEP (Programmatical Processing Evidence). After creating an SR policy as a container, one or more candidate paths can be associated with the SR policy container without encoding the SR policy when creating a new candidate path. Similarly, existing candidate paths can be modified or deleted without encoding the SR policy as the candidate paths change.

[0027] Another object of the present invention is to provide a mechanism for deleting SR strategies independent of candidate paths.

[0028] Therefore, in one implementation, the present invention provides a method executed by a Path Computation Element (PCE) using the Path Computation Element Protocol (PCEP). The method includes sending a first PCEP initialization message to a Path Computation Client (PCC). The first PCEP initialization message includes a Central Controller Instruction (CCI) having a Controller Identifier (CC-ID) (X) for creating a Segment Routing (SR) policy. Furthermore, the method includes receiving a first PCEP report message from the PCC when creating the SR policy, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID (X) has been created.

[0029] In one implementation, the PCE acts as a PCE Central Controller (PCECC).

[0030] In another implementation, a method is disclosed that is executed by a Path Computation Client (PCC) using the Path Computation Element Protocol (PCEP). The method includes receiving a first PCEP initialization message from a Path Computation Element (PCE). The first PCEP initialization message includes a Central Controller Instruction (CCI) having a Controller Identifier (CC-ID) (X) for creating a Segment Routing (SR) policy. Furthermore, the method includes receiving a first PCEP report message from the PCC when the SR policy is created, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID (X) has been created.

[0031] In another implementation, a Path Computation Element (PCE) using the Path Computation Element Protocol (PCEP) is disclosed. The PCE includes a first memory for storing PCEP objects containing Central Controller Instructions (CCIs) having a Central Controller Identifier (CC-ID) (X) for creating Segment Routing (SR) policies. Furthermore, the PCE includes a first transceiver for sending a first PCEP initialization message to a Path Computation Client (PCC), the first PCEP initialization message including a CCI having a CC-ID (X) for creating the SR policy. Additionally, the first transceiver is configured to receive a first PCEP report message from the PCC when the SR policy is created, the first PCEP report message being a report from the PCC that the SR policy corresponding to the CC-ID (X) has been created.

[0032] In another implementation, a path computation client (PCC) using the Path Computation Element Protocol (PCEP) is disclosed. The PCC includes a second memory for storing a first list comprising one or more segment routing (SR) policies created independently of the candidate paths at the PCC, and a second list comprising one or more candidate paths and a corresponding SR policy association identifier for each of the one or more candidate paths, the SR policy association identifier corresponding to an SR policy in the first list. Furthermore, the PCC includes a second transceiver for receiving a first PCEP initialization message from a Path Computation Element (PCE). The first PCEP initialization message includes a Central Controller Instruction (CCI) having a CC-ID(X) for creating an SR policy. Additionally, the PCC includes a second processor for creating the SR policy and storing the SR policy in the first list. Furthermore, the second transceiver is used to send a first PCEP report message to the PCE when the SR policy is created. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created.

[0033] In another implementation, a system is disclosed comprising a Path Computation Element (PCE) and a Path Computation Client (PCC) communicating with each other using the Path Computation Element Protocol (PCEP). The PCE includes a first memory for storing PCEP objects containing Central Controller Instructions (CCIs) having a Central Controller Identifier (CC-ID) (X) for creating Segment Routing (SR) policies. Furthermore, the PCE includes a first transceiver for sending a first PCEP initialization message to the PCC, the first PCEP initialization message including a CCI having a CC-ID (X) for creating the SR policy. Additionally, the first transceiver is configured to receive a first PCEP report message from the PCC during the creation of the SR policy, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID (X) has been created. The PCC includes a second memory for storing a first list of one or more Segment Routing (SR) policies created independently of the candidate paths at the PCC, and a second list of one or more candidate paths and corresponding SR policy association identifiers for each of the one or more candidate paths, the SR policy association identifiers corresponding to SR policies in the first list. Furthermore, the PCE includes a second transceiver for receiving the first PCEP initialization message from the PCE. Additionally, the PCE includes a second processor for creating the SR policy and storing the SR policy in the first list. Furthermore, the second transceiver is used to send the first PCEP report message to the PCE when the SR policy is created.

[0034] Compared to existing technologies, the main advantage of embodiments of the present invention is that it eliminates the need to send all SR policy information along with each candidate path belonging to the same SR policy. The central control mechanism supported by PCEP is used to create SR policies as empty containers on the PCC without simultaneously creating candidate paths on the PCE. Therefore, the complexity of sending SR policy parameters along with each candidate path is reduced, as is the complexity of searching for the availability of SR policies sent along with each candidate path from the PCE to the PCC. The ultimate overall effect is that SR policies can be created, modified, and deleted independently of candidate paths.

[0035] The various options and preferred embodiments of the first implementation described above are also applicable to other implementations. Attached Figure Description

[0036] The specific implementation is described with reference to the accompanying drawings. In the drawings, the leftmost number of the reference numerals indicates the drawing in which that reference numeral first appears. All drawings use the same numbers to refer to similar features and components.

[0037] Figure 1 A schematic diagram of a label switching network according to one implementation of the present invention is shown.

[0038] Figure 2 A schematic diagram of a node according to one implementation of the present invention is shown.

[0039] Figure 3 A method according to an embodiment of the present invention is shown.

[0040] Figure 4 A method for PCE execution according to an embodiment of the present invention is shown.

[0041] Figure 5 A method for PCE execution according to another embodiment of the present invention is shown.

[0042] Figure 6 A method for PCE execution according to yet another embodiment of the present invention is shown.

[0043] Figure 7 A method for PCE execution according to yet another embodiment of the present invention is shown.

[0044] Figure 8 A method for PCE execution according to yet another embodiment of the present invention is shown.

[0045] Figure 9 A method for PCC execution according to an embodiment of the present invention is shown.

[0046] Figure 10 A method for PCC execution according to another embodiment of the present invention is shown.

[0047] Figure 11 A method for PCC execution according to yet another embodiment of the present invention is shown.

[0048] Figure 12 A method for PCC execution according to yet another embodiment of the present invention is shown.

[0049] Figure 13 A method for PCC execution according to yet another embodiment of the present invention is shown.

[0050] Figure 14 A schematic diagram of a PCE according to one implementation of the present invention is shown.

[0051] Figure 15 A schematic diagram of a PCC according to one implementation of the present invention is shown.

[0052] Figure 16 A schematic diagram of a system including a PCE and a PCC according to one implementation of the present invention is shown.

[0053] It should be understood that the accompanying drawings are for illustrative purposes and should not be construed as limiting the scope of the invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0055] This invention can be implemented in various ways as a process, apparatus, system, combination of substances, computer-readable medium, such as a computer-readable storage medium or computer network, wherein program instructions are transmitted via optical or electronic communication links. In this specification, these implementations or any other form in which the invention may take are referred to as techniques. Generally, the order of steps in the disclosed process can be modified within the scope of this invention.

[0056] The following provides a detailed description of one or more embodiments of the present invention, along with accompanying drawings illustrating the principles of the invention. While the invention has been described in conjunction with these embodiments, it is not limited to any particular embodiment. The scope of the invention is limited only by the claims, and the invention includes many alternatives, modifications, and equivalents. Numerous specific details are set forth in the following description to provide a thorough understanding of the invention. These details are provided for illustrative purposes, and the invention may be practiced without some or all of these specific details. For clarity, known technical information in the art related to the invention has not been described in detail to avoid unnecessary obfuscation of the invention.

[0057] The following detailed description sets forth numerous specific details to provide a thorough understanding of the invention. However, those skilled in the art will understand that the invention can be practiced without these specific details. In other instances, well-known methods, processes, components, modules, units, and / or circuits have not been described in detail so as not to obscure the invention.

[0058] Although the embodiments of the present invention are not limited thereto, discussions using terms such as “processing,” “calculating,” “determining,” “establishing,” “analyzing,” and “checking” can refer to the operation and / or process of a computer, computing platform, computing system, or other electronic computing device that manipulates and / or converts data (represented as physical (e.g., electronic) quantities in computer registers and / or memory) into other data, which are similarly represented as physical quantities in computer registers and / or memory or other informational non-transitory storage media that can store instructions to perform the operation and / or process.

[0059] While embodiments of the invention are not limited thereto, the term "multiple" as used herein may include, for example, "a plurality" or "two or more". The term "multiple" may be used throughout the specification to describe two or more components, devices, elements, units, parameters, etc. Unless explicitly stated otherwise, the method embodiments described herein are not limited to a particular order. Furthermore, some of the described method embodiments or elements thereof may occur or be performed simultaneously at the same point in time.

[0060] This invention relates to the instantiation of segment routing (SR) policies via the Path Computation Element Protocol (PCEP). According to embodiments of the invention, the Path Computation Element (PCE) instantiates the SR policy at the Path Computation Client (PCC). The PCE and PCC communicate with each other using PCEP messages, which are also defined in the Internet drafts entitled "PCEP Procedures and Protocol Extensions Using PCE as a Central Controller (PCECC) for LSP" and "PCEP Extensions Supporting Candidate Paths for Segment Routing Policies." Therefore, the PCE can operate according to the instructions of the central controller, or it can act as the Path Computation Element Central Controller (PCECC) using the already defined PCEP extensions.

[0061] An SR strategy comprises one or more candidate paths, which can be computed by a PCE. In existing mechanisms, candidate paths instantiated by the PCE at the PCC send additional information to map the candidate paths to their SR strategies. Each candidate path is mapped to a unique Path Label Switched Path-Identifier (PLSP-ID) in the PCEP. Existing mechanisms create LSP groups, which can be used to define associations between a set of LSPs, thereby associating multiple candidate paths belonging to the same SR strategy together. Furthermore, existing mechanisms define PCEP association objects, also known as "SR strategy associations," by defining association types, specifically for associating SR candidate paths to a single SR strategy.

[0062] This invention aims to provide a mechanism that supports initializing SR policies independently of candidate paths. For an SR policy, the SR policy parameters are color and endpoint. This allows the creation of SR policies to be instantiated and independent of candidate paths. Subsequently, for a set of candidate paths belonging to the same SR policy, instantiation can be performed. At least for the first candidate path, the SR policy parameters and association type (SR policy associations are already defined in the Internet draft) are exchanged between the PCE and PCC. For subsequent candidate paths, since only the SR policy association ID is exchanged, it is not necessary to exchange all SR policy parameters for each candidate path instantiated on the PCC from the PCE. One of the key advantages of creating SR policies as candidate path-independent containers is that SR policies can be preserved even if a candidate path fails in the network. The above embodiments disclose the invention in more detail.

[0063] Figure 1A schematic diagram of a tag-switching network 100 is shown. In a Software Defined Network (SDN), a PCE is enabled as a Path Computation Element Central Controller (PCECC). The tag-switching network 100 includes a control plane controller 120, at least one PCE 130, and multiple nodes 112. In one implementation, the PCE 130 may act as a PCECC. In another implementation, the PCE 130 may be implemented in a node 112 and, in other implementations, operates according to instructions from the control plane controller 120. The role of the PCE as a PCECC is known and therefore will not be discussed in detail in this invention. The components of the tag-switching network 100 communicate with each other via optical, electrical, or wireless means. When the tag-switching network is a packet-switched network, data traffic is transmitted along network paths or routes using packets or frames. Data packets can be routed or switched along a Label Switched Path (LSP) established by a signaling protocol such as MPLS or Generalized MPLS (GMPLS) based on the path calculated by the PCE and / or developed by Node 112. Node 112 is any device or component that supports the transmission of data packets over Label Switched Network 110. For example, Node 112 may include bridges, switches, routers, or various combinations of such devices. Node 112 includes multiple ingress ports for receiving data packets from other Nodes 112, logic circuitry for determining which Node 112 to send a frame to, and multiple egress ports for transmitting frames to other Nodes 112. In some embodiments, at least some of Nodes 112 are label switched routers (LSRs) for modifying or updating the labels of data packets transmitted in Label Switched Network 110. In some embodiments, some of Nodes 112 are label edge routers. (router, LER). For example, node 112 at the edge of label switching network 110 is used to insert or remove labels from data packets transmitted between label switching network 110 and external networks. The first node 112 and the last node 112 along the path are sometimes referred to as the source node or headend node and the destination node or tail node, respectively. Although four nodes 112 are shown in label switching network 110, label switching network 110 may include any number of nodes 112. Furthermore, nodes 112 may be located in different domains within label switching network 110 and may be used for communication across multiple domains. For example, nodes 112 corresponding to different domains may exchange data packets along paths established across multiple domains.Control plane controller 120 is any device used to coordinate activities within label switching network 110, such as a network management system (NMS) or operations support system (OSS). Specifically, control plane controller 120 receives routing requests from label switching network 110 and returns corresponding path information. Furthermore, control plane controller 120 communicates with PCE 130 (e.g., using PCEP), providing PCE 130 with information for path calculation, receiving the calculated path from PCE 130, and forwarding the calculated path to at least one of nodes 112. Control plane controller 120 may reside in a component outside label switching network 110, such as an external server, or it may reside in a component inside label switching network 110, such as node 112.

[0064] PCE 130 is any device used to perform all or part of the path calculation for the label switching network 110 based on a path calculation request. Specifically, PCE 130 receives information for path calculation from control plane controller 120, node 112, or both. PCE 130 then processes the information to obtain the path. For example, PCE 130 calculates the path and determines node 112 that includes LSRs along the path. PCE 130 can then send all or part of the calculated path information to control plane controller 120 or directly to at least one node 112. Furthermore, PCE 130 is typically coupled to or includes a traffic-engineering database (TED), a P2MP path database (PDB), a point-to-point path database, an optical performance monitor (OPM), a physical layer constraint (PLC) information database, or a combination thereof, which can be used to calculate the path. PCE 130 can be located in a component outside the label switching network 110, such as an external server, or it can be located in a component inside the label switching network 110, such as node 112.

[0065] The path calculation request is sent by the PCC to the PCE 130. The PCC can be any client application requesting path calculation to be performed by the PCE 130. The PCC can also be any network component issuing such a request, such as the control plane controller 120, or any node 112, such as an LSR. For example, the PCC requests a P2MP path or point-to-point path within a single domain or across multiple domains in the label-switched network 110 from the PCE. Furthermore, the PCC can send at least some path-related information to the PCE 130 via a PCEP path calculation request and / or via broadcast signaling through link state advertisements (LSAs).

[0066] Data packets transmitted between network nodes, such as node 112, are called label-switched packets and include labels for exchanging the packets among nodes along a calculated path. The path calculated or given by MPLS and signaled for transmitting or routing label-switched packets is called an LSP. For example, an LSP can be a TELSP established using the Resource Reservation Protocol-Traffic Engineering (RSVP-TE) extension. An LSP can be a point-to-point TE LSP, extending from a source node to a destination node, and is unidirectional, where packets are transmitted in one direction along the path, for example, from a source node to a destination node in label-switched network 110. Alternatively, an LSP can be a P2MP TE LSP, extending from a source node or root node to multiple destination nodes or leaf nodes. A P2MP TE LSP can be viewed as a combination of multiple point-to-point TE LSPs sharing the same source node.

[0067] The above description of PCE and PCC is known to those skilled in the art and does not limit the invention disclosed herein in any way.

[0068] Figure 2 This is a schematic diagram of an exemplary embodiment of node 200, where node 200 may represent PCE 130, and node 112 may include PCE and PCC, as shown. Figure 1As shown. In some embodiments, node 200 may implement all or part of the methods described below with respect to the PCE and PCC disclosed herein. Those skilled in the art will recognize that the term node 112 is included for clarity of discussion, but in no way is it intended to limit the application of the invention to a particular node. At least some of the features / methods described in this invention are implemented in network nodes, devices, or components (e.g., node 200). For example, the features / methods in this invention are implemented using hardware, firmware, and / or software installed to run on hardware. Node 200 may be any device that transmits data, such as packets, frames, streams, and / or data streams, over a network, such as a switch, router, bridge, server, client, etc. Figure 2 As shown, node 200 includes transceivers (Tx / Rx) 210, which are transmitters, receivers, or a combination thereof. Tx / Rx 210 is coupled to multiple downlink ports 220 for transmitting and / or receiving frames from other nodes; Tx / Rx 210 is coupled to multiple uplink ports 250 for transmitting and / or receiving frames from other nodes. Processor 230 is coupled to Tx / Rx 210 to process frames and / or determine which nodes to send frames to. Processor 230 may include one or more multi-core processors and / or memory modules 240 for use as data storage, buffers, etc. Processor 230 is implemented as a general-purpose processor or as part of one or more application-specific integrated circuits (ASICs) and / or digital signal processors (DSPs). Processor 220 may include a PCE controller module (not shown) for providing PCE and SDN functionality, as well as functions supporting the methods, computations, and / or communications described herein. In another embodiment, the PCE controller module (PCECC) is implemented as instructions stored in memory module 240, which are executed by processor 230. Memory module 240 includes a cache for temporary storage of content, such as random access memory (RAM). Additionally, memory module 240 includes long-term storage for storing relatively long-term content, such as read-only memory (ROM). For example, the cache and long-term storage include dynamic random access memory (DRAM), a solid-state drive (SSD), a hard disk, or a combination thereof.

[0069] It should be understood that by programming and / or loading executable instructions onto node 200, at least one of processor 230, cache, and long-term storage is altered, partially transforming node 200 into a specific machine or device, such as a PCE, which can instantiate the SR strategy in a path-independent manner according to the functions taught in this invention. Functionality that can be implemented by loading executable software onto a computer can be translated into hardware implementations using well-known design rules, which are fundamental in the fields of electrical engineering and software engineering. The decision to implement a concept using software or hardware typically depends on considerations of design stability and the number of units to be produced, rather than any issues involved in the translation from the software domain to the hardware domain. Generally, designs that are frequently modified are better implemented in software because redesigning a hardware implementation is more expensive than redesigning software. Generally, stable designs for mass production are better implemented in hardware, such as in ASICs, because hardware implementations are cheaper than software implementations for large-scale production operations. Typically, designs are developed and tested in software form and then translated into an equivalent hardware implementation in an ASIC using well-known design rules, which hard-wires the software instructions. Similar to how a machine controlled by a new ASIC is a specific machine or device, a computer that has been programmed and / or loaded with executable instructions is considered a specific machine or device.

[0070] As mentioned above, Figure 1 An embodiment of a label-switched network is illustrated, in which the PCE can act as a central controller, referred to as the PCECC. The PCE calculates path control information for each node and transmits the calculated path control information to each node. In some embodiments, the PCE communicates with each node via the PCEP.

[0071] According to an embodiment of the present invention, the path calculation request is sent from the PCC to the PCE, wherein the PCC can be any client application requesting the PCE to perform path calculation. The PCC can also be any network component issuing such a request, such as... Figure 1 Any node shown. The PCE calculates the path (e.g., route) and determines the nodes (e.g., LSRs along the path), and directly sends all or part of the calculated path information to each node along the path. In existing mechanisms, the PCE initializes an SR policy with a single candidate path or multiple candidate paths. When instantiating one or more candidate paths on the PCC, the PCE needs to signal the PCC to the <header, color, endpoint, initiator, identifier, priority> tuple, and the PCC can use the tuple to instantiate the candidate path of the identified SR policy. Therefore, the SR policy is always bound to the candidate path.

[0072] According to the present invention, the SR strategy can be created at nodes independent of candidate paths. In one implementation, the PCE can be based on a central controller (e.g., Figure 1 It operates according to the instructions of the central plane controller; or acts as a PCECC to operate on one or more nodes (e.g., Figure 1 An SR policy is created at node 112) as a separate container. The PCE, as a PCECC, can implement the embodiments claimed in this invention using existing PCECC technology. To this end, a new Central Controller Instruction (CCI) object type is proposed in the PCECC extension, which creates SR policies according to the teachings of this invention. It should be understood that each CCI is identified by a unique identifier (called CC-ID) in the PCEP. As an example, the Internet draft "PCEP Procedures and Protocol Extensions for Using PCE as a Central Controller (PCECC) of LSP" defines PCEP objects for encoding CCIs limited to label forwarding instructions, which can be identified by their unique CC-ID. To create SR policies independent of candidate paths, this invention discloses a new CCI object type that allows CCIs to create SR policies in a manner independent of candidate paths.

[0073] The CCI object type used to create SR policies encodes an SR policy parameter called the policy identifier and an optional Type-Length-Value (TLV) carrying the SR policy name. The policy identifier uniquely identifies the SR policy to which a given LSP belongs within the header context. The policy identifier includes: the SR policy header, the SR policy color, the SR policy endpoints, and an optional policy name. The optional TLV for the CCI object type used to create SR policies is the SRPOLICY-POL-NAME TLV. Specifically defined as:

[0074] SRPOLICY-POL-NAME TLV:

[0075]

[0076] Wherein, "Type" indicates the associated type = TBD3, which is the type as understood in the art. Furthermore, the total length of the TLV's "Length" in octet units must be greater than 0. Policy Name: The policy name, as defined in [InternetDraft.ietf-spring-segment-routing-policy].

[0077] Therefore, this invention proposes a new CCI object type with a CC-ID, which creates SR policies on nodes independent of candidate paths. In the context of this invention, the PCE uses a CCI object with a CC-ID (X) (where X is for illustrative purposes only) to instantiate the creation of the SR policy into the PCC, and the creation of the SR policy is independent of candidate paths. The new CCI object is also called a new PCEP object and is defined by an object class value and a CCI object type. The CCI object can be carried in a PCEP message, as detailed below. Therefore, the CCI object disclosed herein is defined as follows:

[0078] SR policy IPv4 CCI object type

[0079]

[0080] SR Policy IPv6 CCI Object Type

[0081]

[0082] Among them, one of the two SR policy CCI object types is used for IPv4 and the other for IPv6, defined as follows:

[0083] Wherein, CC-ID: PCEP-specific identifier for CCI information. The PCE creates a CC-ID for each instruction; this value is unique within the PCE and remains unchanged throughout the lifecycle of the PCEP session. Values ​​0 and 0xFFFFFFFF are reserved and must not be used. In this invention, for illustrative purposes, the CC-ID is referred to as value X. "Color" can be an unsigned 32-bit number, and "Header" and "Endpoint" are IPv4 or IPv6 addresses based on the CCI object type. Furthermore, "Header," "Color," and "Endpoint" are the same as the SR policy parameters. An optional TLV is used to encode the existing TLV defined above: SRPOLICY-POL-NAME TLV.

[0084] As described above, the CCI object is carried by the PCEP message from PCE to PCC. The PCEP message is used for central controller instructions and is defined in [RFC8281]. In the context of this invention, existing messages supporting the functionality required for PCECC can be defined as:

[0085] (1) PCInitiate (PCE Initialization) message: This is referred to as the first PCEP message in this document, and is described in [RFC8281].

[0086] (2) PCRpt (PC Report) message: This is referred to as the second PCEP message in this paper and is described in [RFC8231].

[0087] (3) PCUpd (PC Update) message: This is referred to as the third PCEP message in this document and is described in [RFC8231].

[0088] According to an embodiment of the present invention, a first PCEP message, namely a PCInitiate message, is used to carry a CCI with a CC-ID(X) from the PCE to the PCC for creating an SR policy. The first PCEP message carries a CCI that creates an SR policy independently of the candidate paths. After the SR policy is created, subsequent PCEP messages can be used to associate the SR policy with one or more candidate paths using an association ID. Thereafter, when creating a new candidate path, only the association ID is exchanged in the PCEP messages, not the SR policy parameters. It should be noted that the Internet draft "draft-ietf-pce-segment-routing-policy-cp-00" has defined SR policy associations, which allow candidate paths to be created as a subset of new or existing SR policies. Therefore, when the PCE wants to instantiate one or more candidate paths on the PCC, it needs to send SR policy parameters, which the PCC can use to instantiate candidate paths for the identified SR policy. However, this invention does not require SR policies to be mapped to candidate paths by default, and allows the creation of SR policies as containers. When such SR policies are to be assigned to said candidate paths, the containers can later be associated with one or more candidate paths using an association ID selected by the PCC. Association parameters that uniquely identify the association between one or more candidate paths of an SR policy have been described in the Internet draft "draft-ietf-pce-segment-routing-policy-cp-00" and are incorporated herein by reference. To clearly distinguish between the candidate path instantiation disclosed in the Internet draft "draft-ietf-pce-segment-routing-policy-cp-00" and the candidate path-independent SR policy instantiation disclosed in this invention, reference is now made to... Figure 3 The diagram illustrates a PCEP message used for communication between the PCE and PCC, where the PCE is... Figure 1 The PCE 130 shown, wherein the PCC is Figure 1 The node shown is 112.

[0089] In step 302, PCE 130 sends a first PCEP initialization message PCInitiate to PCC 112. This first PCEP message carries a central controller instruction with CC-ID=X for creating an SR policy. The central controller instruction may include SR policy parameters. Candidate path instantiation is not performed in this step.

[0090] PCC 112 receives the first PCEP initialization message from PCE 130 and creates an SR policy using SR policy parameters. The SR policy is a container that is independent of any candidate path.

[0091] In step 304, PCC 112 sends a first PCEP report message PCRpt to PCE 130 to report the confirmation of CC-ID=X and the newly created SR policy.

[0092] Steps 302 and 304 are proposed in this invention and do not exist in existing Internet drafts because, prior to the publication of this invention, it was unknown how to create an SR strategy independently of one or more candidate paths.

[0093] In step 306, PCE 130 sends a second PCEP initialization message, PCInitiate, to PCC 112. This second PCEP message is used to create a new candidate path (CP1) and includes an association object for associating the candidate path with the created SR policy. The association object includes a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy.

[0094] In step 308, PCC 112 sends a second PCEP report message PCRpt to PCE 130 to report the newly created candidate path (CP1) and include the associated ID corresponding to the SR policy.

[0095] Subsequently, when a candidate path (CP1) needs to be updated or deleted, only the association ID is sent from PCE 130 to PCC 112, and the entire SR policy parameters or TLV set does not need to be sent. Furthermore, when a new candidate path (CP2) needs to be created, only the SR policy association, i.e., the association ID, is sent, without sending the entire SR policy parameter set.

[0096] like Figure 3 As shown, in step 310, PCE 130 sends a PCEP update message PCUpd to PCC 112. This update message is used to update the existing candidate path (CP2). The PCEP update message includes an association ID, referred to as the SR policy association.

[0097] Compared to existing internet drafts, Figure 3 The illustrations provided are only for clarifying the use of new CCIs for creating SR strategies independent of candidate paths, and do not limit the claimed invention in any way. The concepts of associated objects and associating new candidate paths with the created SR strategies are known and will not be elaborated upon further below.

[0098] The above-described embodiments of the invention have been explained with the aid of exemplary figures and one or more examples. However, these exemplary figures are provided to better understand the invention and should not be construed as limiting the scope of the invention.

[0099] Figure 4 Method 400 is illustrated, executed by a Path Computation Element (PCE) using the Path Computation Element Protocol (PCEP). Here, PCE may refer to PCE130, which can operate according to instructions from a central controller or act as a pre-existing... Figure 1 The PCECC discussed earlier. The PCE can also be one of the nodes 112 that operate according to instructions from the central controller. In this embodiment, the PCE acts as the PCECC. According to an embodiment of the invention, method 400 includes step 402, wherein the PCE sends a first PCEP initialization message to the PCC, which can be... Figure 1 Node 112 is described in the text. The first PCEP initialization message includes a Central Controller Instruction (CCI) with a Central Controller Identifier (CC-ID) (X) for creating a Segment Routing (SR) policy. Here, step 402 can be considered equivalent to... Figure 3 The above step 302 is shown. The CCI object used to create an SR policy independent of the candidate path and with CC-ID=X has been described above and will not be repeated here. Furthermore, method 400 includes step 404, whereby the PCE receives a first PCEP report message from the PCC when creating the SR policy. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created. Here, step 404 can be considered equivalent to... Figure 3 The above step 304 is shown. When an SR policy is created as a separate container, one or more candidate paths can be associated with an already created SR policy. One of the main advantages of creating an SR policy as a separate container is that the SR policy is not necessarily deleted, but is retained, even if a candidate path fails in the network.

[0100] also, Figure 5 A method 500 for creating a candidate path (CP1) according to an embodiment of the present invention is shown, wherein an SR policy has previously been created at the PCC, therefore method 500 is derived from... Figure 4The PCE execution mentioned above. Method 500 includes step 502, in which the PCE sends a second PCEP initialization message to the PCC to associate the candidate path (CP1) with the created SR policy, wherein the second PCEP initialization message includes a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy. Here, step 502 can be considered equivalent to Figure 3 The above-described step 306 is shown. Furthermore, the method includes step 504, whereby the PCE receives a second PCEP report message from the PCE, the second PCEP report message being used to report the association between the created candidate path (CP1) and the SR policy, and including the association ID corresponding to the SR policy. The method for creating candidate paths during PCE initialization has been described in the Internet draft "draft-ietf-pce-segment-routing-policy-cp-00" and is incorporated herein by reference. Here, step 504 can be considered equivalent to... Figure 3 The above step 308 is shown in the diagram. It should be noted that this invention differs clearly from the aforementioned Internet draft, namely, the SR policy is created separately in method 400, and candidate paths are now created and associated with the SR policy via an association ID. However, in the previous scheme, candidate paths were created while sharing SR policy parameters, and the PCE was unaware of whether the SR policy existed or needed to be created. Therefore, one of the key advantages of creating the SR policy as a separate container and then associating it with one or more candidate paths is that it is not necessary for the PCE to know whether the SR policy exists or needs to be created.

[0101] also, Figure 6 A method 600 for creating another candidate path (CP2) according to an embodiment of the present invention is shown, wherein an SR policy has already been created at the PCC, therefore method 600 is derived from... Figure 4 and Figure 5The PCE execution mentioned above. Furthermore, since another candidate path (CP2) is created, it can be assumed that a previous candidate path (CP1) existed. Both the previous candidate path (CP1) and the other candidate path (CP2) are used for the same SR policy created as disclosed in method 400 above. Method 600 includes step 602, in which a third PCEP initialization message is sent to the PCC to associate the other candidate path (CP2) with the created SR policy, the third PCEP initialization message including an association ID instead of SR policy parameters. An advantage associated with this step is that after sharing the SR policy parameter set for the first candidate path (CP1) created and associated with the SR policy, it is not necessary to share it again for other candidate paths to be associated with the same SR policy. The association ID is sent from the PCE to the PCC. The PCC uses the association ID to associate the candidate path (CP2) with the created SR policy. In step 604, the PCE receives a third PCEP report message from the PCC, the third PCEP report message being used to report the association of the created candidate path (CP2) with the SR policy, and including the association ID.

[0102] In another embodiment, methods 400 and 500 described above further include method 700 for updating existing candidate paths. By sharing only the association ID to the created existing SR policy, existing candidate paths can be updated without sharing the SR policy parameter set. In step 700, the PCE sends a PCEP update message, including sending a PCEP update message to the PCC to update the candidate path (CP1), the PCEP update message including the association ID. Here, method 700 can be considered equivalent to... Figure 3 The above step 310 is shown in the illustration. Similarly, as... Figure 3 As shown, method 700 may also include receiving confirmation from PCC (PCRpt) when updating candidate paths associated with SR strategies.

[0103] According to another embodiment of the present invention, the SR policy created using the disclosed method 400 can be deleted by sharing CC-ID=X using the fourth PCEP initialization message (PCInitiate). Figure 8 A method 800 executed by a PCE is shown, wherein the PCE sends a fourth PCEP initialization message to a PCC, the fourth PCEP initialization message being used to delete the SR policy and including a CC-ID(X).

[0104] Figure 9Method 900, executed by a Path Computation Client (PCC) using the Path Computation Element Protocol (PCEP), is illustrated. Here, PCC can refer to... Figure 1 Node 112 is discussed in the text. The PCC communicates with the PCE, which can operate according to instructions from the central controller and can also act as... Figure 1 The PCECC discussed earlier. Here, PCE refers to the PCE executing methods 400, 500, 600, 700, and 800. According to an embodiment of the invention, method 900 includes step 902, wherein the PCC receives a first PCEP initialization message from the PCE. The first PCEP initialization message includes a Central Controller Instruction (CCI) having a Central Controller Identifier (CC-ID) (X) for creating a Segment Routing (SR) policy. Here, step 902 can be considered equivalent to... Figure 3 The above step 302 is shown. The CCI object used to create an SR policy independent of the candidate path and with CC-ID=X has been described above and will not be repeated here. Furthermore, method 900 includes step 904, wherein the PCC sends a first PCEP report message to the PCE when creating the SR policy. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created. Here, step 904 can be considered equivalent to... Figure 3 The above step 304 is shown. When an SR policy is created as a separate container, one or more candidate paths can be associated with an already created SR policy. One of the main advantages of creating an SR policy as a separate container is that the SR policy is not necessarily deleted, but is retained, even if a candidate path fails in the network.

[0105] also, Figure 10 A method 1000 for creating a candidate path (CP1) according to an embodiment of the present invention is shown, wherein an SR policy has been previously created at the PCC, therefore method 1000 is derived from... Figure 9 The PCC execution mentioned above. Method 1000 includes step 1002, wherein the PCC receives a second PCEP initialization message from the PCE to associate the candidate path (CP1) with the created SR policy, the second PCEP initialization message including a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy. Here, step 1002 can be considered equivalent to Figure 3The above-described step 306 is shown. Furthermore, the method includes step 1003, where the PCC associates the candidate path (CP1) with the created SR policy. Additionally, the method includes step 1004, where the PCC sends a second PCEP report message to the PCE, the second PCEP report message reporting the association between the created candidate path (CP1) and the SR policy, and including the association ID corresponding to the SR policy. Therefore, one of the key advantages of creating the SR policy as a separate container and then associating it with one or more candidate paths is that it is not necessary for the PCE to know whether the SR policy exists or must be created.

[0106] also, Figure 11 A method 1100 for creating another candidate path (CP2) according to an embodiment of the present invention is shown, wherein an SR policy has already been created at the PCC, therefore method 1100 is derived from... Figure 9 and Figure 10 The PCC mentioned above is executed. Furthermore, since another candidate path (CP2) is created, it can be assumed that a previous candidate path (CP1) existed. Both the previous candidate path (CP1) and the other candidate path (CP2) are used for the same SR policy created as disclosed in method 900 above. Method 1100 includes step 1102, wherein a third PCEP initialization message is received from the PCE to associate the other candidate path (CP2) with the created SR policy, the third PCEP initialization message including an association ID instead of SR policy parameters. An advantage associated with this step is that after sharing the SR policy parameter set for the first candidate path (CP1) created and associated with the SR policy, it is not necessary to share it again for other candidate paths to be associated with the same SR policy. The association ID is sent from the PCE to the PCC. Furthermore, the method includes step 1103, wherein the PCC associates the other candidate path (CP2) with the created SR policy. The PCC uses the association ID to associate the candidate path (CP2) with the created SR policy. In step 1104, the PCC sends a third PCEP report message to the PCE. The third PCEP report message is used to report the association between the created candidate path (CP2) and the SR policy, and includes the association ID.

[0107] In another embodiment, methods 900 and 1000 described above further include method 1200 for updating existing candidate paths. By sharing only the association ID with the created existing SR policy, existing candidate paths can be updated without sharing the SR policy parameter set. In step 1202, the PCC receives a PCEP update message from the PCE to update the candidate path (CP1), the PCEP update message including the association ID. Here, method 1202 can be considered equivalent to... Figure 3 The above step 310 is shown in the illustration. Similarly, as... Figure 12As shown, method 1200 may further include sending an acknowledgment from PCC (PCRpt) to PCE when updating candidate paths associated with SR policies. Method 1200 may also include, in step 1204, PCC identifying the SR policy associated with the candidate path from the association ID and updating the candidate path (CP1) within the SR policy.

[0108] According to another embodiment of the present invention, the SR policy created using the disclosed method 900 can be deleted by receiving CC-ID=X using the fourth PCEP initialization message (PCInitiate) from the PCE. Figure 13 A method 1300 executed by a PCC is shown, wherein the PCC receives a fourth PCEP initialization message from a PCE, the fourth PCEP initialization message being used to delete an SR policy and including a CC-ID(X).

[0109] In addition to methods 400 and 900 performed by the PCE and PCC respectively, as described above, both the PCE and PCC must indicate their support for the functionality described in this invention, namely, the ability to create SR policies independent of candidate paths. This is achieved by mutually announcing the defined capability TLV in the OPEN object. The definition of the OPEN object is known in the PCECC extension and will not be repeated here. Accordingly, the method performed by the PCE may include announcing to the PCC in an open PCEP message that the PCE supports CCI to create SR policies independent of candidate paths, said announcement being made before sending the first PCEP initialization message. Similarly, the method performed by the PCC may include announcing to the PCE in an open PCEP message that the PCC supports CCI to create SR policies independent of candidate paths, said announcement being made before receiving the first PCEP initialization message.

[0110] According to yet another embodiment of the present invention, an apparatus and system are disclosed that support CCI in creating SR strategies independent of candidate paths.

[0111] Now for reference Figure 14 According to an embodiment of the present invention, a path computation element (PCE) 1400 executing according to the Path Computation Element Protocol (PCEP) is shown. Here, PCE may refer to PCE 130, which can operate according to instructions from a central controller or act as a pre-existing... Figure 1 The PCECC discussed earlier. The PCE can also be one of the nodes 112 that operate according to instructions from the central controller. In this embodiment, the PCE acts as the PCECC. Although considering Figure 14The components shown are used to explain the invention, but it should be understood that PCE 1400 may include... Figure 2 The elements and functions disclosed in node 200 are as follows. Furthermore, it can be understood from this invention that PCE 1400 communicates with a Path Computation Client (PCC) using PCEP. PCE 1400 includes memory 1402 and transceiver 1404. For clarity, and to distinguish the elements of PCE 1400 from those of PCC in this invention, memory 1402 is hereinafter referred to as first memory 1402, and transceiver 1404 is hereinafter referred to as first transceiver 1404. Similarly, PCE 1400 may include a processor ( Figure 14 (not shown in the image), such as Figure 2 As shown at node 200, the processor is referred to as the first processor. It should be understood that the first memory 1402 and the first transceiver 1404 can be considered identical to memory 240 and transceiver 210, respectively, as described above regarding... Figure 2 As explained by node 200. According to this embodiment, PCE 1400 is used to execute the methods 400, 500, 600, 700, and 800 described above. For this purpose, first memory 1402 is used to store PCEP objects having a Central Controller Instruction (CCI) with a Central Controller Identifier (CC-ID) (X) for creating a Segment Routing (SR) policy. Furthermore, first transceiver 1404 is used to send a first PCEP initialization message to the PCC, which may be... Figure 1 Node 112 is described in the document. The first PCEP initialization message includes a CCI with a CC-ID(X) for creating a Segment Routing (SR) policy and a parameter set for the SR policy. Furthermore, a first transceiver 1404 is used to receive a first PCEP report message from the PCC when the SR policy is created. This first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) and the SR policy parameter set have been created. Therefore, PCE differs from the prior art in that it supports the creation of SR policies independent of candidate paths. One of the main advantages of creating SR policies as separate containers is that the SR policy is not necessarily deleted but is retained even if a candidate path fails in the network.

[0112] Furthermore, the first transceiver 1404 is used to perform the functions disclosed in the methods 500 to 800 detailed above, and therefore will not be described again here. Figure 15The corresponding PCC for creating the SR policy when the PCE 1400 is instantiated is shown.

[0113] Now for reference Figure 15 According to an embodiment of the present invention, a path computation client (PCC) 1500 executing according to the Path Computation Element Protocol (PCEP) is shown. Here, PCC can refer to a path computation client already in use. Figure 1 Node 112, which was discussed earlier. Although considering... Figure 15 The components shown are used to explain the invention, but it should be understood that the PCC 1500 may include... Figure 2 The components and functions disclosed in node 200 are as follows. Furthermore, it can be understood from this invention that PCC 1500 communicates with PCE 1400 using PCEP. PCC 1500 includes a second memory 1502, a second transceiver 1504, and a second processor 1506. The phrase "second" used for components of PCC 1500 is for clarity and to distinguish components of PCC 1500 from those of PCE 1400 in this invention. It should be understood that the second memory 1502, the second transceiver 1504, and the second processor 1506 can be considered the same as memory 240, transceiver 210, and processor 230, respectively, as described above regarding... Figure 2As explained by node 200. According to this embodiment, PCC 1500 is used to execute methods 900, 1000, 1100, 1200, and 1300 described above. For this purpose, a second memory 1502 is used to store a first list and a second list. The first list includes one or more segment routing (SR) policies created at the PCC, independent of candidate paths. The second list includes one or more candidate paths and a corresponding SR policy association identifier for each of the one or more candidate paths, the SR policy association identifier corresponding to an SR policy in the first list. Furthermore, a second transceiver 1504 is used to receive a first PCEP initialization message from PCE 1400, the first PCEP initialization message including a Central Controller Instruction (CCI) having a Central Controller Identifier (CC-ID) (X) for creating a segment routing (SR) policy and a parameter set for the SR policy. Furthermore, a second processor 1506 is used to create SR policies and store the SR policies in the first list. When creating an SR policy, the second transceiver 1504 sends a first PCEP report message to the PCE. This first PCEP report message is used by the PCC to report that the SR policy and the SR policy parameter set corresponding to the CC-ID(X) have been created. Therefore, the difference between the PCC and existing technologies is that it supports the creation of SR policies independent of candidate paths. One of the main advantages of creating SR policies as separate containers is that the SR policy is not necessarily deleted but retained even if a candidate path fails in the network.

[0114] Furthermore, the second transceiver 1504 performs the functions disclosed in methods 1000 to 1300 detailed above, and therefore will not be described again here. After the PCC receives the second PCEP initialization message, the second processor 1506 associates the candidate path (CP1) with the associated ID in the second list. Furthermore, when the PCC receives a PCEP update message, the second processor 1506 identifies the SR policy associated with the candidate path from the associated IDs and updates the candidate path (CP1) within the SR policy. Furthermore, upon receiving the third PCEP initialization message, the second processor 1506 associates the candidate path (CP2) with the associated ID in the second list. Furthermore, after the PCC receives the fourth PCEP initialization message, the second processor 1506 removes the SR policy from the first list. Furthermore, upon receiving the third PCEP initialization message, the second processor 1506 associates the candidate path (CP2) with the associated ID in the second list.

[0115] According to yet another embodiment, a system 1600 is disclosed, including a PCE 1602 and a PCC 1604 communicating with each other using a PCEP. In one implementation, the PCE 1602 includes... Figure 14 The publicly disclosed PCE 1400 and PCC 1604 include Figure 15 The publicly disclosed PCC 1500. In another implementation, PCE 1602 and PCC 1604 include... Figure 2 Public node 200. In another implementation, PCE 1602 includes... Figure 1 The publicly disclosed PCE 130, PCC includes Figure 1 Public node 112. According to this embodiment, system 1600 implements... Figure 3The disclosed method supports the creation of SR policies independent of candidate paths using PCEP extensions. The functionality of PCE 1602 is defined relative to PCE 1400, and the functionality of PCC 1604 is defined relative to PCC 1500. For example, PCE 1602 includes a first memory 1402 for storing PCEP objects of Central Controller Instructions (CCIs) having a Central Controller Identifier (CC-ID) (X) for creating Segment Routing (SR) policies. Furthermore, the PCE includes a first transceiver for sending a first PCEP initialization message to PCC 1604. The first PCEP initialization message includes a set of parameters for the CCI and the SR policy having a CC-ID (X) for creating the Segment Routing (SR) policy. Furthermore, the first transceiver is configured to receive a first PCEP report message from PCC 1604 when creating an SR policy. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) and the SR policy parameter set have been created. PCC 1604 includes a second memory and a second transceiver. The second memory is used to store a first list and a second list. The first list includes one or more segment routing (SR) policies created at the PCC, independent of candidate paths. The second list includes one or more candidate paths and a corresponding SR policy association identifier for each of the one or more candidate paths, the SR policy association identifier corresponding to an SR policy in the first list. Furthermore, the second transceiver is configured to receive a first PCEP initialization message from PCE 1602 and send the first PCEP report message to the PCE when creating an SR policy. PCC 1604 also includes a second processor for creating SR policies and storing the SR policies in the first list. Therefore, System 1600, including PCE 1602 and PCC 1604, differs from existing technologies because it supports the creation of SR policies independent of candidate paths. One of the main advantages of creating SR policies as separate containers is that the SR policies are not necessarily deleted, but are retained, even if a candidate path fails in the network.

[0116] According to another embodiment, the first transceiver of PCE 1602 is used to perform the functions disclosed in the first transceiver 1404 of PCE 1400. Furthermore, the second transceiver and the second processor are used to perform the functions of the second transceiver 1504 and the second processor 1506 of PCC 1500, respectively.

[0117] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the above systems, devices and units can be referred to the corresponding processes in the above method embodiments, and will not be repeated here.

[0118] While several embodiments have been provided in this invention, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the scope of the invention. The examples presented here are intended to be illustrative rather than restrictive and are not intended to be limited to the details given herein. For example, various elements or components may be combined or integrated into another system, or some features may be omitted or not implemented.

[0119] Furthermore, without departing from the scope of the invention, the technologies, systems, subsystems, and methods described and illustrated as discrete or separate in the various embodiments can be combined or integrated with other systems, modules, technologies, or methods. Other items shown or described as coupled to each other, or directly coupled, or communicating with each other, may be indirectly coupled or communicated electrically, mechanically, or otherwise through some interface, device, or intermediate component. Other examples of variations, substitutions, and modifications can be determined by those skilled in the art and may be exemplified without departing from the scope of this disclosure.

[0120] Therefore, the scope of protection is not limited as described above, but is defined by the appended claims, which include all equivalents of the subject matter of the appended claims. Each and every claim is incorporated in the specification as further disclosure, and the claims are embodiments of the invention. References in the disclosure are not an admission of prior art, especially any references with a publication date after the priority date of the prior application of this application.

[0121] Finally, the language used in this specification has been chosen primarily for readability and guidance, rather than for recounting or limiting the subject matter of the invention. Therefore, the scope of the invention is not limited by this detailed description, but rather by any of the claims set forth in this application. Thus, the disclosure of embodiments of the invention is intended to be illustrative and not to limit the scope of the invention, which is set forth in the claims.

Claims

1. A method executed by a Path Computation Element (PCE) using the Path Computation Element Protocol (PCEP), characterized in that, include: Send a first PCEP initialization message to the Path Computation Client (PCC). The first PCEP initialization message includes: A Central Controller Instruction (CCI) with a Central Controller Identifier (CC-ID) (X) is used to create a Segment Routing (SR) policy that is independent of candidate paths. When creating the SR policy, a first PCEP report message is received from the PCC, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created.

2. The method according to claim 1, characterized in that, Also includes: Send a second PCEP initialization message to the PCC to associate the candidate path (CP1) with the created SR policy. The second PCEP initialization message includes a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy. Receive a second PCEP report message from the PCC, the second PCEP report message being used to report the association between the created candidate path (CP1) and the SR policy, and including the association ID corresponding to the SR policy.

3. The method according to claim 2, characterized in that, This includes sending a PCEP update message to the PCC to update the candidate path (CP1), the PCEP update message including the association ID.

4. The method according to claim 2, characterized in that, include: Send a third PCEP initialization message to the PCC to associate another candidate path (CP2) with the created SR policy. The third PCEP initialization message includes the association ID, but not the SR policy parameters. Receive a third PCEP report message from the PCC, the third PCEP report message being used to report the association between the created candidate path (CP2) and the SR policy, and including the association ID corresponding to the SR policy.

5. The method according to claim 1, characterized in that, include: Send a fourth PCEP initialization message to the PCC, the fourth PCEP initialization message being used to delete the SR policy and including the CC-ID(X).

6. The method according to claim 1, characterized in that, The first PCEP initialization message includes a color field, a header field, and an endpoint field. These fields are SR policy parameters. The color field is an unsigned 32-bit number. The header field and the endpoint field are respectively based on the IPv4 address or IPv6 address of the CCI object type. The optional TLV corresponds to the "SRPOLICY-POL-NAME TLV" used to encode the name of the SR policy.

7. The method according to claim 1, characterized in that, The PCE acts as the PCE Central Controller (PCECC).

8. The method according to claim 1, characterized in that, include: The PCE is notified to the PCC in an open PCEP message to instruct the PCE to support CCI to create an SR policy independent of candidate paths, and the notification is completed before sending the first PCEP initialization message.

9. A method executed by a Path Computation Client (PCC) using the Path Computation Element Protocol (PCEP), characterized in that, include: The system receives a first PCEP initialization message from the Path Computation Element (PCE). The first PCEP initialization message received from the PCE includes: A Central Controller Instruction (CCI) with a Central Controller Identifier (CC-ID) (X) is used to create a Segment Routing (SR) policy that is independent of candidate paths. When the SR policy is created, a first PCEP report message is sent to the PCE. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created.

10. The method according to claim 9, characterized in that, Also includes: Receive a second PCEP initialization message from the PCE, and associate the candidate path (CP1) with the created SR policy. The second PCEP initialization message includes a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy. Associate the candidate path (CP1) with the created SR strategy; Send a second PCEP report message to the PCE. The second PCEP report message is used to report the association between the created candidate path and the SR policy, and includes the association ID corresponding to the SR policy.

11. The method according to claim 10, characterized in that, include: Receive a PCEP update message from the PCE to update the candidate path (CP1), the PCEP update message including the association ID; Identify the SR policy associated with the candidate path from the association ID, and update the candidate path (CP1) in the SR policy.

12. The method according to claim 10, characterized in that, include: Receive a third PCEP initialization message from the PCE, and associate another candidate path (CP2) with the created SR policy. The third PCEP initialization message includes the association ID, but not the SR policy parameters. Associate the other candidate path (CP2) with the created SR strategy; Send a third PCEP report message to the PCE. The third PCEP report message is used to report the association between the created candidate path (CP2) and the SR policy, and includes the association ID corresponding to the SR policy.

13. The method according to claim 9, characterized in that, include: Receive a fourth PCEP initialization message from the PCE, the fourth PCEP initialization message being used to delete the SR policy and including the CC-ID(X); Identify the SR policy from the CC-ID(X) and delete the SR policy.

14. The method according to claim 9, characterized in that, include: The PCE is notified in an open PCEP message to instruct the PCC to support CCI to create SR policies independent of candidate paths, and the notification is completed before receiving the first PCEP initialization message.

15. A path computation element (PCE) using the Path Computation Element Protocol (PCEP), characterized in that, The PCE includes: The first memory is used to store PCEP objects of Central Controller Instruction (CCI), which have a Central Controller Identifier (CC-ID) (X) for creating a segment routing (SR) policy independent of candidate paths. The first transceiver is used for Send a first PCEP initialization message to the Path Computation Client (PCC). The first PCEP initialization message includes: CCI with CC-ID(X) for creating SR strategies independent of candidate paths; When creating the SR policy, a first PCEP report message is received from the PCC, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created.

16. The PCE according to claim 15, characterized in that, The first transceiver is also used for: Send a second PCEP initialization message to the PCC to associate the candidate path (CP1) with the created SR policy. The second PCEP initialization message includes a set of SR policy parameters and an SR policy association identifier (association ID) corresponding to the SR policy. The system receives a second PCEP report message from the PCC. The second PCEP report message is used to report the association between the created candidate path and the SR policy, and includes the association ID corresponding to the SR policy.

17. The PCE according to claim 16, characterized in that, The first transceiver is used to send a PCEP update message to the PCC to update the candidate path (CP1), and the PCEP update message includes the association ID.

18. The PCE according to claim 17, characterized in that, The first transceiver is used for: Send a third PCEP initialization message to the PCC to associate another candidate path (CP2) with the created SR policy. The third PCEP initialization message includes the association ID, but not the SR policy parameters. Receive a third PCEP report message from the PCC, the third PCEP report message being used to report the association between the created candidate path (CP2) and the SR policy, and including the association ID corresponding to the SR policy.

19. The PCE according to claim 15, characterized in that, The first transceiver is used for: Send a fourth PCEP initialization message to the PCC, the fourth PCEP initialization message being used to delete the SR policy and including the CC-ID(X).

20. The PCE according to claim 15, characterized in that, The first transceiver is used for: The PCE is notified to the PCC in an open PCEP message to instruct the PCE to support CCI to create an SR policy independent of candidate paths, and the notification is completed before sending the first PCEP initialization message.

21. A path computing client (PCC) using the Path Computation Element Protocol (PCEP), characterized in that, The PCC includes: A second memory is used to store a first list including one or more segment routing (SR) policies created independently of the candidate paths at the PCC, and a second list including one or more candidate paths and a corresponding SR policy association identifier for each of the one or more candidate paths, the SR policy association identifier corresponding to an SR policy in the first list. The second transceiver is used for: Receive a first PCEP initialization message from the Path Computation Element (PCE), the first PCEP initialization message including: It has a Central Controller Instruction (CCI) for creating CC-ID(X) independent of candidate path SR strategies. The second processor is used to create the SR policy and store the SR policy in the first list; The second transceiver is used to send a first PCEP report message to the PCE when the SR policy is created. The first PCEP report message is used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created.

22. The PCC according to claim 21, characterized in that: The second transceiver is also configured to receive a second PCEP initialization message from the PCE, and associate the candidate path (CP1) with the created SR policy. The second PCEP initialization message includes the SR policy parameter set and the SR policy association identifier (association ID) corresponding to the SR policy. The second processor is used to associate the candidate path (CP1) with the associated ID in the second list; The second transceiver is used to send a second PCEP report message to the PCE. The second PCEP report message is used to report the association between the created candidate path and the SR policy, and includes the association ID corresponding to the SR policy.

23. The PCC according to claim 22, characterized in that: The second transceiver is used to receive a PCEP update message from the PCE to update the candidate path (CP1), the PCEP update message including the association ID; The second processor is used to identify the SR policy associated with the candidate path from the association ID, and update the candidate path (CP1) in the SR policy.

24. The PCC according to claim 22, characterized in that, The transceiver is used for: The second transceiver is used to receive a third PCEP initialization message from the PCE, which associates another candidate path (CP2) with the created SR policy. The third PCEP initialization message includes the association ID, but not the SR policy parameters. The second processor is used to associate the candidate path (CP2) with the associated ID in the second list; The second transceiver is used to send a second PCEP report message to the PCE. The second PCEP report message is used to report the association between the candidate path (CP2) and the SR policy, and includes the association ID corresponding to the SR policy.

25. A system comprising a path computing element (PCE) and a path computing client (PCC) communicating with each other using the Path Computation Element Protocol (PCEP), characterized in that: The PCE includes: The first memory is used to store PCEP objects of Central Controller Instruction (CCI), which have a Central Controller Identifier (CC-ID) (X) for creating a segment routing (SR) policy independent of candidate paths. The first transceiver is used for: Send a first PCEP initialization message to the PCC, the first PCEP initialization message including: CCI with CC-ID(X) for creating SR strategies independent of candidate paths; When the SR policy is created, a first PCEP report message is received from the PCC, the first PCEP report message being used by the PCC to report that the SR policy corresponding to the CC-ID(X) has been created; The PCC includes: A second memory is used to store a first list including one or more segment routing (SR) policies created independently of the candidate paths at the PCC, and a second list including one or more candidate paths and a corresponding SR policy association identifier for each of the one or more candidate paths, the SR policy association identifier corresponding to an SR policy in the first list. A second transceiver is used to receive the first PCEP initialization message from the PCE; The second processor is used to create the SR policy and store the SR policy in the first list; The second transceiver is used to send the first PCEP report message to the PCE when the SR policy is created.

26. The system according to claim 25, characterized in that: The first transceiver is also used to send a second PCEP initialization message to the PCC, associating the candidate path (CP1) with the created SR policy. The second PCEP initialization message includes the SR policy parameter set and the SR policy association identifier (association ID) corresponding to the SR policy. The second transceiver is also configured to receive the second PCEP initialization message from the PCE to associate the candidate path (CP1) with the created SR policy; The second processor is used to associate the candidate path (CP1) with the associated ID in the second list; The second transceiver is used to send a second PCEP report message to the PCE. The second PCEP report message is used to report the association between the created candidate path and the SR policy, and includes the association ID corresponding to the SR policy. The first transceiver is used to receive the second PCEP report message from the PCC.

27. The system according to claim 26, characterized in that: The first transceiver is used to send a PCEP update message to the PCC to update the candidate path (CP1), and the PCEP update message includes the association ID; The second transceiver is used to receive a PCEP update message from the PCE to update the candidate path (CP1), the PCEP update message including the association ID; The second processor is used to identify the SR policy associated with the candidate path from the association ID, and update the candidate path (CP1) in the SR policy.

28. The system according to claim 25, characterized in that: The first transceiver is used to send a PCEP initialization message to the PCC, associating another candidate path (CP2) with the created SR policy. The PCEP initialization message includes the association ID but does not include the SR policy parameters. The second transceiver is used to receive a PCEP initialization message from the PCE, and associate another candidate path (CP2) with the created SR policy. The PCEP initialization message includes the association ID but does not include the SR policy parameters. The second processor is used to associate the candidate path (CP2) with the associated ID in the second list; The second transceiver is used to send a second PCEP report message to the PCE. The second PCEP report message is used to report the association between the candidate path (CP2) and the SR policy, and includes the association ID corresponding to the SR policy. The first transceiver is used to receive the second PCEP report message from the PCC.

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