CN114244771A

CN114244771A - PECP segmented routing path segmented label binding extension

Info

Publication number: CN114244771A
Application number: CN202111670696.5A
Authority: CN
Inventors: 马亨德拉·辛格·尼基; 普雷耶特·卡拉达哈兰
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-07-07
Filing date: 2018-07-05
Publication date: 2022-03-25
Also published as: WO2019007390A1; CN110870261A; CN110870261B

Abstract

The present specification discloses a method for supporting establishment of a Segment Routing traffic engineering Label Switched Path (SR-TE LSP), without considering the limitation of a forwarding node on the Maximum Segment Depth (MSD). A Path Computation Element (PCE) learns the SRID (i.e., label) from all Path Computation Clients (PCC), because the PCC runs an Inter Gateway Protocol (IGP) and is consistent with a Traffic Engineering DataBase (TEDB). The conventional technology is limited to label assignment using PCE. They do not guide nor suggest label assignment using PCC. The present invention associates an incoming label with an outgoing label stack and label range that the PCE uses for a sub-LSP (i.e., a portion of the LSP). The PCE is capable of generating a label binding from a defined label range (i.e., label type 3) and sending the label binding to a network device.

Description

PECP segmented routing path segmented label binding extension

Technical Field

The invention described herein relates generally to communication networks and, more particularly, to integrating segment routing with multiprotocol label switching with longer path segments in legacy systems. More particularly, the present invention relates to a method and apparatus for transmitting data packets in a communication network.

Background

Traditional routing techniques require an SDN (Software Defined Networking, SDN for short) controller to interact directly with each node involved in a traffic path. The granularity and temporal nature of the traffic flow may cause scalability problems due to the routing state that needs to be maintained in the core network nodes and the required configuration traffic.

Segment Routing (SR) is an emerging technology that can simplify the implementation of traffic engineering in WANs. SR provides full control of the forwarding path by combining simple network instructions, eliminating the need for any additional protocols, and sometimes even removing unnecessary protocols to simplify the network. SR simplifies routing by delegating configuration and flow-by-flow state at network boundaries. In the SR, path signaling is not needed, and only the flow-by-flow state needs to be maintained at the access node of the SR domain, so that the network flexibility is improved and the cost is reduced. Segmented routing allows traffic to be directed along arbitrary paths in the network, allowing operators to implement low latency and/or split paths without regard to traditional/normal forwarding paths.

Multiprotocol Label Switching (MPLS) is a protocol for carrying data in a high performance telecommunications network. MPLS directs data from one network node to the next based on a short-path label rather than the long network address traditionally used, thereby avoiding complex lookup work in the routing table. These labels identify virtual links (paths) between distant nodes, not between endpoints. MPLS can encapsulate messages of various network protocols, and is therefore referred to as "multiprotocol". In MPLS, each packet is marked by an ingress router when entering the service provider network, and all subsequent routing switches forward the encapsulated data only according to the label, thereby eliminating the need to route traffic by looking at the IP header. The egress router removes the label and forwards the original IP packet to its final destination.

Notably, segment routing can be applied directly in MPLS architectures without changing their forwarding plane. SR can utilize network bandwidth more efficiently while providing lower latency than traditional MPLS networks. The segments are encoded as MPLS labels, the ordered list of segments is encoded as a stack of labels, the segment to be processed is at the top of the stack, and after a segment is completed, the associated label is popped from the stack.

Segmented routing provides automatic traffic protection without topological constraints. The network protects traffic from link and node failures without additional signaling in the network. The existing fast-route (FRR) technology can ensure full protection coverage of the best backup path by combining with explicit routing capability in segment routing. Traffic protection does not cause any additional signaling requirements.

Using Segment Routing Traffic Engineering (SR-TE for short) -MPLS, nodes direct messages through an ordered list of instructions called segments (MPLS labels). The ingress node inserts fragments (i.e., label stacks) to direct the packets to a particular path in the network. When the Segment routing tunnel is computed by the centralized controller, the controller must know the Maximum Segment Depth (MSD) of the node or link SR tunnel egress to ensure that it does not download a path with a Depth that exceeds the SID (label stack) that the node or link in use can tolerate.

Notably, older systems (old routers or low-end hardware devices) have a limit on the number of fragments inserted (since the MSD value or hop count in SR-TE of these systems is typically 3 to 5), failing to meet the needs of the complete SR-TE path (label stack inserted at ingress). Notably, these systems have MSD values of at least 2.

Thus, in the old system, the hardware limitations of MSD or hop count in SR-TE have not been realized in the old system where SR-TE was implemented and where the SR-TE path crossed a hop beyond the MSD value (e.g., if the number of nodes involved in the data route is greater than 3 to 5). More specifically, due to certain hardware limitations of the old system, for example, if its MSD value is 3, the router is the ingress node of the segment routing tunnel when the SR-TE is established, and the maximum number of hops between the ingress node of the segment routing tunnel and the egress node of the segment routing tunnel can only be 3, i.e., the number of hops cannot be greater than 3.

Therefore, there is a need to introduce a mechanism to implement SR-TE-MPLS in the old system to eliminate the restriction that the SR-TE path across the hop needs to be the same as the MSD value, i.e. to introduce a way to set up longer segment routing tunnels in the old system.

The above-described deficiencies of implementing SR-TE-MPLS in legacy systems are intended merely to outline some of the problems of conventional systems/mechanisms/techniques, and are not exhaustive. Other problems with conventional systems/mechanisms/techniques and the corresponding advantages of the various non-limiting embodiments described herein will become more apparent in the following summary.

Disclosure of Invention

This summary is provided to introduce concepts related to a method for implementing a SR-TE LSP (Label Switched Path, LSP for short) across a network to provide a longer SR-TE Path, and is further described below in the detailed description. This summary is not intended to identify essential features of the claimed invention, nor is it intended to be used to determine or limit the scope of the claimed invention.

The object of the present invention is to solve the above technical problem by providing a label stack and binding the label stack with an incoming label.

It is another object of the present invention to enable the establishment of SR-TE LSPs across a network to provide longer SR-TE paths.

It is a further object of the present invention to provide an apparatus for establishing longer segment routing tunnels in legacy systems.

It is still another object of the present invention to provide a method for transmitting a data packet in a communication system.

It is still another object of the present invention to provide an apparatus for transmitting a data packet in a communication system.

According to a first aspect of the present invention, a method of transmitting data packets in a communication system is provided. The method comprises the following steps: a first network device receives a first packet through a first adjacent segment of the SR-TE path, where the first adjacent segment is located between a first Label Switching Router (LSR) and the first network device, and the first packet includes a first incoming label and a second packet; according to the first message and the corresponding relation between the first incoming label and a first label stack, the first network device determines the first label stack; generating, by the first network device, a third packet according to the first incoming label, where the third packet includes the first label stack and the second packet; segmenting a first path of the SR-TE path, and sending the third message to a second network device by the first network device, wherein the first label stack comprises at least one adjacent segment identifier (Adj-SID), and the first path segment is identified by the at least one Adj-SID in the first label stack; the first network device is an ingress node of the first path segment, and the second network device is an egress node of the first path segment.

In one implementation of the first aspect, the present invention provides a method for supporting SR-TE LSP establishment to provide a longer SR-TE path. A Path Computation Element (PCE) learns SRIDs (labels) from all Path Computation Clients (PCCs), that is, the PCCs run an Interior Gateway Protocol (IGP), and are consistent with a Traffic Engineering DataBase (Traffic Engineering DataBase, TEDB).

According to a second aspect of the present invention, there is provided a system for transmitting data packets in a communication network. The system includes a first network device. The first network device includes: a memory, configured to receive a first packet through a first adjacent segment of a segment routing traffic engineering (SR-TE) path; the first message comprises a first incoming label and a second message; a processor configured to identify the first packet from the memory, wherein the processor is configured to: determining a first label stack according to the first message, mapping between the first incoming label and the first label stack, and generating a third message according to the first label stack, wherein the third message comprises the first label stack and the second message; a transceiver, configured to send the third packet generated by the processor to a second network device along a first path segment of the SR-TE path.

According to a third aspect of the present invention, a network apparatus for transmitting data packets in a communication system is provided. The device comprises: a memory, configured to receive a first packet through a first adjacent segment of a segment routing traffic engineering (SR-TE) path; the first message comprises a first incoming label and a second message; a processor configured to identify the first packet from the memory, wherein the processor is configured to: determining a first label stack according to the first message, mapping between the first incoming label and the first label stack, and generating a third message according to the first label stack, wherein the third message comprises the first label stack and the second message; a transceiver, configured to send the third packet generated by the processor.

In contrast to the prior art, the present invention associates an incoming label with an outgoing label stack and label range that the PCE uses for a child LSP (i.e., a portion of the LSP). The conventional technology is limited to label assignment by PCE. As with the present invention, they do not teach nor suggest the assignment of label binding tags by PCCs.

The various options and preferred embodiments mentioned above in relation to the first embodiment are also applicable to the other embodiments.

Drawings

The detailed description is described with reference to the accompanying drawings. In the drawings, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. The same numbers are used throughout the drawings to reference like features of components.

FIGS. 1a and 1b are flow diagrams illustrating a network deployment scenario for establishing SR-TE LSPs in a conventional routing system according to an embodiment of the present invention;

FIG. 2 illustrates a network deployment scenario for establishing an SR-TE LSP with 9 nodes between an ingress and an egress according to an embodiment of the present invention;

FIG. 3 illustrates a new label range with label type 3 from PCC to PCE provided by an embodiment of the present invention;

FIG. 4 illustrates another network deployment scenario for establishing SR-TE LSPs provided by another embodiment of the present invention, wherein

The SR-TE LSP has 5 nodes between an ingress and an egress;

fig. 5 illustrates LSP-setup with label binding for a transport node or network device provided by an embodiment of the present invention including P2, P4, and P6;

fig. 6 illustrates LSP deletion with a label splicing transport node or network device including P2, P4, and P6 according to an embodiment of the present invention;

FIG. 7 illustrates a STATEFUL-PCE-CAPABILITY TLV (type, length, and value) format provided by an embodiment of the invention;

FIG. 8 illustrates a tag range object format (New tag type 3) provided by an embodiment of the present invention;

fig. 9 illustrates a network apparatus for sending data packets according to another embodiment of the present invention.

It is to be understood that the appended drawings are intended to illustrate the concepts of the invention and may not be drawn to scale.

Detailed Description

The invention can be implemented in numerous ways, including as a process, an apparatus, a system, a composition of matter, a computer readable medium such as a computer readable storage medium or a computer network wherein program instructions are sent over optical or electronic communication links. In this specification, these embodiments, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention.

The following provides a detailed description of one or more embodiments of the invention and accompanying drawings that illustrate the principles of the invention. The invention is described in connection with these embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention.

Although embodiments of the invention are not limited in this respect, discussions utilizing terms such as, for example, "processing," "computing," "calculating," "determining," "establishing", "analyzing", and "checking" or the like, may refer to operation(s) and/or process (es) of a computer, a computing platform, a computing system, or other electronic computing device, that manipulate and/or transform data represented as physical (e.g., electronic) quantities within the computer's registers and/or memories into other data similarly represented as physical quantities within the computer's registers and/or memories or other information non-transitory storage medium that may store instructions for performing the operations and/or processes.

Although embodiments of the present invention are not limited in this respect, the terms "plurality" and "a plurality" as used herein may include, for example, "a multiple" or "two or more". The terms "plurality" or "a plurality" may be used throughout the specification to describe two or more components, devices, elements, units, parameters and the like. The method embodiments described herein are not limited by a particular order or sequence unless explicitly stated. Furthermore, some of the method embodiments or elements described herein may occur or be performed concurrently, or at the same point in time, or in parallel.

Although the embodiment of the present invention does not limit this, the term SR-TE Path is MPLS Label Switching Path (LSP). The SR-TE path may be represented by an ordered set of SIDs. Further, the term "path segment" refers to a portion of a path, and in particular, a portion of an SR-TE path. Further, the term "adjacency-segment" denotes a hop on a particular adjacency between two nodes in the IGP. It is noted that in most cases, the contiguous segment is a one-hop path.

The embodiment of the application discloses a method for realizing the establishment of an SR-TE LSP (Single Carrier-time traffic protocol) across networks, which does not need to consider the limitation of a forwarding node on MSD (Multi-level data traffic).

In describing aspects of the method for implementing SR-TE LSP establishment across a network without regard to the limitations of forwarding nodes on MSDs, the present invention may be implemented in any number of different computing systems, environments, and/or configurations, and embodiments are described in the context of the following exemplary systems, devices/nodes/apparatuses and methods.

Embodiments of the invention may be explained hereinafter with the aid of exemplary diagrams and one or more examples. Such exemplary figures and examples, however, are provided for illustrative purposes in order to better understand the present invention and should not be construed as limiting the scope of the present invention.

An LSP is a path between Provider Edge (PE) routers. PCE sessions are established with all forwarding nodes (PCCs), IGPs publish SR-TE NLRI (node/adjacency) segment identities across IGP domains, PCE controllers compute the paths and attempt to establish SR-TE LSPs (e.g., if an ingress node has MSDs that cannot support inserting all SR-TE segment paths, then SR-TE paths cannot be established).

The segments represent sub-paths that can be combined by routers to form a complete route to a network destination. Each Segment has an Identifier (SID), which is distributed in the entire network using a new IGP (Interior Gateway Protocol, IGP) extension. The control planes of both IPv4 and IPv6 support the extension. The segment identifier is encoded as an MPLS label stack entry and directs the data along the specified path. A router may request a path to a destination with certain characteristics including delay, bandwidth, diversity, etc. The controller calculates the optimal path and returns a corresponding segment list, such as an MPLS label stack, to the requesting router. In this regard, the router may inject traffic with the segment list without any additional signaling in the network.

A Segment is represented by a 32-bit entity called a Segment ID (SID). A prefix Segment Identifier (SID) identifies a segment routing tunnel leading to the destination indicated by the prefix. The prefix-SID is globally unique and its uniqueness is guaranteed by the operator. The prefix SID maximum value is 2^ A¹⁶-1. The prefix SID is allocated from a Segment Routing Global Block (SRGB), and the prefix SID value is converted into a local MPLS label. The adjacent SID is the local unique SID of the node, and is automatically generated by the node attached to the adjacent SID when the Anycast SID scheme is adopted.

The segment routing control plane may be applied to the MPLS data plane. At this point, the prefix-SID in the MPLS data plane is denoted as LSP, with its path flowing along the shortest path to the prefix, and the adjacent segment-SID is denoted as a cross-table entry pointing to a particular egress data link.

The head end marks the corresponding MPLS label stack on the outgoing message transmitted through the tunnel. Each transmission node or network device along the path uses the top-entry label to select the next label and uses the rest of the label stack to forward/route the packet to the next node until the packet reaches the final destination.

In one implementation, the present invention provides a method for supporting the establishment of SR-TE LSPs without regard to the limitations of the forwarding node on MSD. The PCE learns the SRID (i.e., label) from all PCCs, (i.e., the PCCs run IGP) and keeps consistent with the TEDB. And the PCE calculates the path, creates label binding according to needs, and downloads the label binding to a transmission node along the SR path at the entrance. The label binding is a binding between a label (i.e., an IN label, label type 3) and a label stack (i.e., a portion of an OUT label or sub-LSP (i.e., a Segment Routing Explicit Route Object, SRERO). Once the path-related information is downloaded, the PCC confirms the establishment of the LSP by running a BDF (i.e., Bi-directional Forwarding, or simply BDF) technique on the SR-TE LSP or by OAM (Operations, Administration, and Maintenance, or simply OAM) techniques, and reports the LSP to the PCE.

The invention realizes the establishment of the cross-network SR-TE LSP by downloading the label stack and binding the label stack with the incoming label without considering the limitation of the forwarding node on the MSD. A Path Computation Element Protocol (PCEP) or any other Protocol does not have a mechanism to download a label stack (i.e., a label generated by IGP information) and bind the label stack with an incoming label, and a PCE as a central controller is suitable for creating/downloading a label bound to a forwarding node. Currently available schemes support label binding downloads, but are limited to PCE generated labels.

While the prior art does disclose LSP-setup and forwarding entry downloading procedures, these procedures are limited to PCE-assigned labels (i.e., SRIDs). They do not care about the network at the forwarding node where the label (i.e., SRID) is generated by IGP, nor about the PCE's learning of SRID through BGPLS/PCEPLS. In the present invention, since IGP generates (at each PCC) a global SRID index and a local SRID (i.e., adjacency SID, label derived from SRID) range to the PCE, a new label range is introduced to bind the label stack (i.e., part of LSP). The PCE creates a binding from this range with a portion of the LSP (i.e., a portion of the SRERO) and downloads this binding to a forwarding node (e.g., PE1, P1, P2.... PE 2).

In order to realize the establishment of the SR-TE LSP across the network without considering the limitation of the forwarding device to MSD, the invention discloses encoding PATH-BINDING-TYPE to TE-PATH-BINDING TLV in LSP objects, encoding Explicit Route Object (ERO), namely, Path segment SRERO, in PCLABEL Upd, and encoding a new LABEL RANGE (LABEL-RANGE) Object TYPE, namely, LABEL TYPE 3(Label-TYPE 3), as shown in FIG. 8, for transmitting the LABEL RANGE reserved for PCE from PCC. The PCE sends a PCLabelUpd message with the label binding to all eligible transfer nodes or network devices. Notably, based on the MSD, some forwarding nodes or network devices become eligible nodes for PCEs to download label stitching mappings.

In one implementation, the present invention provides a method for implementing SR-TE LSP establishment to provide a longer SR-TE path. Fig. 1a and 1b show a flow chart of a method for transmitting data packets in a communication network.

Fig. 2 shows a network structure including SR-TE paths. The method shown in fig. 1a and 1b may be implemented in the network structure shown in fig. 2. The implementation of the method shown in fig. 2 below will be discussed with reference to fig. 2.

Notably, the first path segment includes forwarding nodes P2-P3-P4, where P1 may be a first LSR, P2 may be a first network device, P3 may be a second LSR, and P4 may be a second network device. Here, the first in-label may be 3001 and the second in-label may be 4001, the first label stack including two Adj-SIDs. The first label stack may include a second in label 4001. The two Adj-SIDs in the first label stack are 301 and 401, respectively. 301 and 401 identify the tunnel P2-P3-P4, wherein 301 identifies link P2-P3 and 401 identifies P3-P4.

The second path segment includes forwarding nodes PE1-P1-P2, where the third network device may be PE 1. The second packet may be an IP packet, and after receiving the second packet, PE1 may encapsulate a second label stack in the second packet.

The second label stack includes the first in-label (e.g., 3001) and at least one Adj-SID (e.g., 101 and 102). 101 and 102 identify the second path segment (e.g., PE1-P1-P2), 101 identifies PE1-P1, and 201 identifies P1-P2. The third MPLS tunnel includes forwarding nodes P4-P6.

Notably, the first Adj-SID may be 301. 301 identifies the contiguous segment between P2 and P3. 201 identifies the contiguous segment between P1 and P2.

The method of the invention comprises the following steps: receiving (1001), by a first network device (P2), a first packet (3001+ IP) over a first adjacency segment of the SR-TE path, wherein the first adjacency segment is between a first label-switched router (P1) and the first network device (P2), the first packet (3001+ IP) comprising a first incoming label (3001) and a second packet (IP); determining (1002), by the first network device (P2), the first label stack (301, 401) according to the first packet (3001+ IP) and the correspondence between the first incoming label (3001) and the first label stack (301, 401); generating (1003) a third packet by the first network device (P2) according to the first incoming label (3001), wherein the third packet comprises the first label stack (301, 401) and the second packet (IP); -a first path segment (P2-P4) along the SR-TE path, the first network device (P2) sending (1004) the third packet to a second network device (P4), wherein the first label stack (301, 401) comprises at least one adjacency segment identifier (Adj-SID), the first path segment being identified by the at least one Adj-SID in the first label stack (301, 401); wherein the first network device (P2) is an ingress node of the first path segment (P2-P4) and the second network device (P4) is an egress node of the first path segment (P2-P4).

Notably, before the first network device (P2) receives the first message (3001+ IP), the method comprises the steps of: the first network device (P2) reporting (1005) a label range of the first network device (P2) to a path computation element (PCE for short); the first network device (P2) receiving (1006) from the PCE a mapping between a first in-label (3001) and a first label stack (301, 401), wherein the first in-label is assigned by the PCE, the first in-label (3001) belonging to the label range; the third network device (PE1) encapsulates the first incoming label (3001) in the second packet (IP) after learning the first incoming label (3001) from the PCE, wherein the PCE receives the report from the first network device (P2).

The first packet (3001+ IP) is received by the first network device (P2) via a second path segment (P1-P2) of the SR-TE path, and the second path segment (P1-P2) traverses the first adjacent segment, wherein the first network device (P2) is an egress node of the second path segment (P1-P2), and the third network device (PE1) is an ingress node of the second path segment (P1-P2).

Before the second packet (IP) is transmitted along a second path segment (P1-P2) identified by at least one Adj-SID in the second label stack, the third network device (PE1) encapsulates a second label stack in the second packet (IP), wherein the second label stack includes the first in-label (3001) and the at least one Adj-SID.

Notably, the first in-label (3001) is located at a bottom of the second label stack, the first label stack (301, 401) including a second in-label (4001) located at the bottom of the first label stack (301, 401).

The second ingress label (4001) is for the second network device (P4) to forward the second packet (IP) along a third path segment (P4-P6) of the SR-TE path, wherein the second network device (P4) is an ingress node of the third path segment (P4-P6).

Notably, a first Adj-SID identifying a second adjacency segment between the first network device (P2) and a second LSR (P1) is located at the top of the first label stack (301, 401), wherein the first path segment (P2-P4) traverses the second adjacency segment.

FIG. 2 illustrates a network deployment scenario for establishing an SR-TE LSP with 9 nodes between an ingress and an egress according to an embodiment of the present invention; notably, label binding or label splicing is used for IN-label- > label-stack mapping (i.e., the forwarding node operates on the label using this mapping relationship). FIG. 2 explains the message flows by operation a) at PE1, operation b) at P1, operation c) at P2, operation d) at P3, operation e) at P4, operation f) at P5, and operation g) at P6, respectively.

An entity (e.g., a router) performs IGP to publish the SR-TE Adjacency SID (i.e., label) to all nodes of an IGP domain (region/level). The PCEP treatment procedure is as follows:

a) as shown in fig. 7, during PCEP session establishment, the PCE learns MSD and label stitching (i.e., binding) capabilities (L Bit25 in the STATEFUL-PCE-CAPABILITY TLV) and MSD (label stack depth) supported by each PCC, i.e., each network device, from all forwarding nodes (i.e., PE1, P1, P2.... PE 2). For example, the MSD values of all PCCs shown in fig. 2 and 4 are 3.

b) Once the session is established, the network device (hereinafter PCC) assigns a label range reservation for the PCE in a pclresv message. As shown in fig. 8, a new label type (3) is introduced in the label range object, which will be used by the PCE for label stitching (binding, etc.) as shown in fig. 3. Notably, this range can only be used by the PCE to create label bindings.

c) The PCE learns the TEDB/Label-DB from all PCCs through BGPLS (Border Gateway Protocol Link State, BGPLS for short), PCEPLS (PCEP Link State, PCEPLS for short) or IGP.

d) In order to establish the SR-TE tunnel, the PCE computes a path from PE1 to PE2, and the span of the LSP is PE1- > P1- > P2- > P3- > P4- > P5- > P6- > PE 2.

e) Since PE1 has an MSD value of 3, it can only encode 3 tags at most, so the PCE will generate a tag-splice (i.e., IN-Label- > Label-Stack) map for the SR-TE path from the tag range received IN step b for tag type 3 at PE1, P2, P4, and P6.

f) As shown in fig. 5, the PCE sends the label binding map to network devices with label binding capability (i.e., P2, P4, and P6) through pclabeupd, and subsequently, the PCC or network device may send a PCRpt message encoding SRP-ID (Stateful Request Parameter Identifier, SRP-ID for short).

g) Before sending the PCUpd message to the pcc (Ingress), the PCE may choose to wait for PCRpt messages from network devices (i.e., P2, P4, and P6), or send the PCUpd message with the first part of the label stack and the splice label to the Ingress router (PE 1). Once receiving the PCRpt message from Ingress and displaying that the LSP status is UP, the PCE confirms that the LSP status is UP (the LSP status is UP only if the path is normal and can carry traffic) and label splicing is correct; if there is an error, the PCE should delete the label splice, as shown in fig. 6.

Fig. 4 illustrates another network deployment scenario for establishing an SR-TE LSP with 5 nodes between the ingress and egress according to another embodiment of the present invention. IGP publishes SR-TE Adjacency SID (i.e., label) to all nodes of the IGP domain (region/level). The PCEP treatment procedure is as follows:

a) PCEP sessions are established with the PCEs and all forwarding nodes (PE1, P1, P2, P3, and PE 2).

b) In the session establishment process, the PCE learns the label binding CAPABILITY (L Bit in STATEFUL-PCE-CAPABILITY TLV) and MSD (label stack depth) supported by each PCC. Assume that PE1 sends an MSD value of 3.

c) The PCE computes a path for the SR-TE LSP from PE1 to PE2, and the LSP span is PE1- > P1- > P2- > P3- > PE 2.

d) Since the MSD value of PE1 is 3, it can encode only 3 tags at most. Thus, the PCE will generate a label binding (a new binding label for the remaining labels).

e) Since P2 supports the label binding capability, the PCE will send a pclabeupd message with a new label binding at the first network device, and P2 may send a PCRpt message encoding an SRP-ID, as shown in fig. 3. Notably, this range can only be used by the PCE to create label bindings.

f) Before sending the PCUpd message to the pcc (ingress), the PCE may choose to wait for a PCRpt message from a first network device (hereinafter, P2) or send a PCUpd message including the first portion of the label stack and the binding label to a third network device (hereinafter, PE 1). Upon receiving the PCRpt message from Ingress, the PCE confirms that the LSP is established and that the label binding is correct, and if false, the PCE should delete the label binding, as shown in fig. 4. Therefore, the PCE sends the PCUpd message to an ingress node, wherein the PCUpd message includes a label switched path with a label binding.

g) SR-TE tunnels (LSPs) span PE1(Ingress) > PE2(Egress)

h) On PE1, the PCE adds SR-TE label stacks (i.e., 201, 301, and 3001) to the IP header in advance according to the path.

i) At a first Label Switching Router (LSR) P1, Label 201 pops up, checks Label 301, and forwards the packet with SR-TE Label stack (i.e., 301 and 30014) to P2.

j) At P2, pop tab 301, check 3001, and since each of the label bindings SR-TE label stacks (i.e., 601 and 701) have been previously added, the message is forwarded normally to P3.

k) At the second LSR P3, label 601 pops up, checks label 701, and forwards the message to PE 2.

Since PE1 only supports MSD 3, a label binding is generated and sent by PCE of P2, and the respective SR-TE path is sent to PCC (PE 1).

And (3) protocol extension:

a) in STATeFULL-PCE-CAPABILITY, L BIT (25) is reserved to support the tag binding CAPABILITY. As shown in FIG. 7, if the L bit is set, the PCE/PCC supports label binding for SR-PATH segments.

b) A label binding update should be added in the existing PCEP message PCLabelUpd to update the label concatenation in the first network device (i.e., P2 of fig. 2).

Notably, the SRP object must encode PATH-BINDING-to download the tag bound to the transport node or network device. The LSP object should be selectively encoded to uniquely identify the LSP; this may be useful for diagnostics. The ERO object encodes a portion of SRERO (i.e., the tag bound to the tag in the PATH-BINDING-TLV). To clear/delete the tag binding, the existing R bit in the SRP object may be used.

c) And adding a tag range object type 3 in the PCRResv message, wherein the tag range object type 3 is used for sending a tag range reserved for the PCE so as to generate tag binding.

The system for sending data messages in a communication network includes a first network device (P2). The first network device (P2) comprising: a memory (101) configured to receive a first packet through a first adjacent segment of a segment routing traffic engineering (SR-TE) path; the first message comprises a first incoming label and a second message; a processor (102) configured to identify the first packet from the memory (101), wherein the processor (102) is configured to: determining a first label stack according to the first message, mapping between the first incoming label and the first label stack, and generating a third message according to the first label stack, wherein the third message comprises the first label stack and the second message; a transceiver (103) configured to send the third packet generated by the processor (102) to a second network device (P4) along a first path segment of the SR-TE path.

As shown in fig. 9, according to a third aspect of the present invention, there is provided a network apparatus (100) for transmitting a data packet in a communication system. It is noted that the network device (100) may perform the method shown in fig. 1a and 1 b. The first network device (100) comprises: a memory (101) configured to receive a first packet through a first adjacent segment of a segment routing traffic engineering (SR-TE) path; the first message comprises a first incoming label and a second message; a processor (102) configured to identify the first packet from the memory, wherein the processor (102) is configured to: determining a first label stack according to the first message, mapping between the first incoming label and the first label stack, and generating a third message according to the first label stack, wherein the third message comprises the first label stack and the second message; a transceiver (103) for transmitting the third message generated by the processor. It is noted that the system for sending data packets in a communication network is provided according to the embodiments of the present application. The system includes the first network device (100) shown in fig. 9.

In the prior art, the PCE assigns and downloads labels to each forwarding node to establish the SR-TE LSP. However, in networks where labels (i.e., SRIDs) are generated by IGP (i.e., PCC) and downloaded to the forwarding plane, the establishment of the SR-TE LSPs is limited to the MSD values of the nodes. To support establishment of SR-TE LSPs without considering the limitations of MSD values, the present invention discloses PCEP extensions such as STATeFULL-PCE-CAPABILITY, L bit (25), reserved for supporting label binding capabilities, and label binding updates added to existing PCEP messages PCLABELIPD, wherein the label binding updates are used to update label splices on the transmitting node or network device.

Through the scheme disclosed by the invention, in order to establish the SR-TE LSP, the PCE can generate label binding from a defined label range (namely label type 3) and send the label binding to a network device, so that the cross-network SR-TE LSP establishment is realized in an old routing system without worrying about the limitation of a forwarding node on MSD.

In addition to the foregoing, some other advantages and features of the present subject matter are as follows:

i. segmented routing with traffic engineering can be implemented in existing networks without upgrading the product to support higher MSDs.

Scalable solution is not product limited.

Migration from existing RSVP-TE scheme to sdn (pce) controlled SR-TE scheme is simpler.

inter-domain or inter-domain LSPs can be created without creating a separate LSP in the next domain.

Those skilled in the art will appreciate that any known or new algorithm may be used to implement the present invention. It should be noted, however, that the present invention provides a method that enables segment routing with traffic engineering in existing networks without upgrading the product to support higher MSDs. Thus, the above advantages and technical advances can be achieved, whether using any known or new algorithms.

Those of ordinary skill in the art will appreciate that the elements and algorithm steps described in connection with the examples disclosed in the embodiments disclosed herein may be embodied in electronic hardware or in a combination of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the several embodiments provided by the present invention, it should be understood that the disclosed methods may be implemented in other ways. For example, the described apparatus embodiments are merely exemplary. For example, a cell partition is merely a logical functional partition, and other partitions are possible in actual implementations. For example, various elements or components may be combined or integrated in another system or portions of features may be omitted, or not implemented. Further, the shown or discussed mutual coupling or direct coupling or communicative connection may be achieved through some interfaces. Direct coupling or communicative connection between devices or units may be achieved through electrical, mechanical, or other means.

These functions may be stored in a computer-readable storage medium when they are implemented in the form of software functional units and sold or used as separate products. Based on this understanding, the solution of the invention can be implemented substantially as or as part of the state of the art or as part of a software product. The computer software product is stored on a storage medium and includes instructions for instructing a computer node (which may be a personal computer, a server, or a network node) to perform all or part of the steps of the method described in embodiments of the present invention. The storage medium described above includes: for example, any medium that can store program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk.

Devices that are in communication with each other need not be in continuous communication with each other unless expressly specified otherwise. Further, devices that are in communication with each other may communicate directly or indirectly through one or more intermediary devices.

Although a single device or article is described herein, it will be readily apparent that more than one device/article, whether or not they cooperate, may be used in place of a single device/article. Similarly, if more than one device or article is described herein (whether or not they cooperate), it will be apparent that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used than the number of devices or programs illustrated. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the present invention need not include the device itself.

Although an embodiment of a method that may enable segmented routing using traffic engineering without requiring product upgrades to support higher MSDs in existing networks has been described in language specific to features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as examples of embodiments of a PCEP segment routing path segment label binding extension.

Claims

1. A method for sending data packets in a communication network, the method comprising the steps of:

a first network device receives a first message through a second path segment of a segment routing traffic engineering (SR-TE) path, where the first message includes a first incoming label and a second message;

the first network device sends a third message to a second network device through a first path segment of the SR-TE path, wherein the third message comprises a first label stack and the second message, and the first label stack is obtained according to the first incoming label; the first network device is an ingress node of the first path segment, and the second network device is an egress node of the first path segment.

2. The method of claim 1, wherein the first label stack comprises at least one adjacency segment identifier (Adj-SID), and wherein the first path segment is identified by the at least one Adj-SID in the first label stack.

3. The method of claim 1 or 2, wherein the first network device is an egress node of the second path segment and a third network device is an ingress node of the second path segment.

4. The method of any of claims 1 to 3, wherein the third network device encapsulates a second label stack to the second packet before the second packet is transmitted over a second path segment identified by at least one Adj-SID in the second label stack, wherein the second label stack comprises the first incoming label.

5. The method of any of claims 1-4, wherein the first in-label is located at a bottom of the second label stack.

6. The method according to any of claims 1 to 5, wherein before the first network device receives the first message, the method further comprises the steps of:

the first network device reports a label range of the first network device to a Path Computation Element (PCE);

the first network device receives the corresponding relation between the first incoming label and the first label stack from the PCE;

wherein the first incoming label is assigned by the PCE, and the first incoming label belongs to the label range;

wherein the first incoming label is encapsulated into the second packet by the third network device after knowing that the first incoming label is from the PCE that received the report of the first network device.

7. The method of any of claims 1-6, wherein the first label stack comprises a second in-label at the bottom of the first label stack.

8. The method of claim 7, wherein the second ingress label is used for the second network device to forward the second packet through a third path segment of the SR-TE path, wherein the second network device is an ingress node of the third path segment.

9. A system for transmitting data packets in a communication network, the system comprising:

a first network device comprising a memory and a processor;

the processor is to execute instructions in the memory to cause the first network device to:

receiving a first packet in a segment mode through a second path of a segment routing traffic engineering (SR-TE) path, where the first packet includes a first incoming label and a second packet;

sending a third message to a second network device through a first path segment of the SR-TE path, wherein the third message comprises a first label stack and the second message, and the first label stack is obtained according to the first incoming label;

the first network device is an ingress node of the first path segment, and the second network device is an egress node of the first path segment.

10. The system of claim 9, wherein the first label stack comprises at least one adjacency segment identifier (Adj-SID), and wherein the first path segment is identified by the at least one Adj-SID in the first label stack.

11. The system according to claim 9 or 10, wherein the first network device is an egress node of the second path segment and a third network device is an ingress node of the second path segment.

12. The system according to any of claims 9 to 11, wherein said third network device encapsulates a second label stack in said second packet before said second packet is transmitted through a second path segment identified by at least one Adj-SID in said second label stack, wherein said second label stack comprises said first incoming label.

13. The system according to any of claims 9 to 12, wherein said first in-label is located at the bottom of said second label stack.

14. The system of any of claims 9 to 13, wherein the processor is configured to execute the instructions in the memory to cause the first network device to further:

reporting the label range of the first network device to a Path Computation Element (PCE).

15. The system of any of claims 9 to 14, wherein the processor is configured to execute the instructions in the memory to cause the first network device to further:

and receiving the corresponding relation between the first incoming label and the first label stack from the PCE.

16. The system according to any of claims 9 to 15, wherein said first incoming label is encapsulated in said second packet by said third network device after learning that said first incoming label is from said PCE that received said report of said first network device.

17. The system according to any of claims 9 to 16, wherein said first label stack comprises a second in-label at the bottom of said first label stack.

18. The system according to any of claims 9 to 17, wherein the second ingress label is used for forwarding the second packet by the second network device through a third path segment of the SR-TE path, wherein the second network device is an ingress node of the third path segment.

19. The system according to any one of claims 9 to 18, wherein said system further comprises said PCE, said PCE configured to receive a label range of said first network device reported by said first network device; acquiring the corresponding relation between the first incoming label and a first label stack; and sending the corresponding relation between the first incoming label and the first label stack to the first network device, wherein the first incoming label belongs to the label range.

20. A first network device for transmitting data packets in a communication system, the first network device comprising: a memory and a processor to execute instructions in the memory to cause the first network device to perform the method of any one of claims 1-8.

21. A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of any one of claims 1 to 8.

22. A computer-readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform the method of any one of claims 1-8.

23. In a communication method applied to a communication system including a Path Computation Element (PCE), a first network device, and a second network device, the method performed by the PCE, the method comprising:

receiving the label range of the first network device reported by the first network device;

acquiring the corresponding relation between the first incoming label and a first label stack;

sending the corresponding relation between the first incoming label and a first label stack to the first network device, wherein the first incoming label belongs to the label range;

the correspondence between the first incoming label and the first label stack is used for the first network device to obtain a first label stack corresponding to the first incoming label after receiving a first packet including the first incoming label and a second packet through a second path segment of a segment routing traffic engineering (SR-TE) path, and to encapsulate the first label stack and the second packet into a third packet and then send the third packet to the second network device through the first path segment of the SR-TE path.

24. A communication device for use in a communication system comprising the communication device, a first network apparatus, and a second network apparatus, wherein the communication device comprises a memory and a processor, the processor being configured to execute instructions in the memory to cause the communication device to:

25. The communication device of claim 24, wherein the communication device is a Path Computation Element (PCE).

26. A computer program product comprising instructions which, when run on a computer, cause the computer to perform the method of claim 23.

27. A computer-readable storage medium comprising instructions that, when executed on a computer, cause the computer to perform the method of claim 23.