CN114760202A - Reliable construction and deployment method of service function chain in network slice scene - Google Patents

Abstract

The invention relates to a reliable construction and deployment method of a service function chain in a network slice scene, belonging to the technical field of mobile communication. The method comprises the following steps: in a network slicing scene, reliably constructing service function chains SFC under a plurality of service requests, constructing a service function graph SFG through the dependency relationship of a Virtual Network Function (VNF) and sharable times by adopting an SFC reliable construction algorithm based on the VNF, selecting the SFG with the highest reliability, and completing the construction of the SFC of the plurality of network slicing service requests; the method comprises the steps of reliably mapping the SFG based on the construction result of the SFG, adopting an SFG mapping algorithm based on delay perception and reliability, mapping and backing up VNF in the SFG to meet the reliability requirement of a user, and using a heuristic algorithm based on node importance to find the optimal solution of a mapping scheme in polynomial time. The invention can ensure the reliability of the SFC in the network and effectively reduce the network resource consumption and the whole service cost.

Description

Reliable construction and deployment method of service function chain in network slice scene

Technical Field

The invention belongs to the technical field of mobile communication, and relates to a reliable construction and deployment method of a service function chain in a network slice scene.

Background

Network Function Virtualization (NFV) and Software Defined Networking (SDN) technologies can run on data center servers located at the edge or core of a network, and are of great significance in the evolution of future networks. In 5G and 6G networks, NFV and SDN can be flexibly deployed and share resources, and meanwhile, the diversity requirements of the vertical industry can be met, so that the application and development of a network slicing technology are promoted. In an actual network, whether the network customized service can normally operate is related to the reliability of the network slicing request. Therefore, in order to improve the reliability of 5G network slice requests, the construction and backup of SFCs should be emphasized.

In network operation, users need highly reliable, long-term, stable services. NFV, while increasing flexibility in network deployment and construction, introduces more unreliable factors due to software and hardware decoupling. In the NFV environment, in order to improve the overall reliability of the network service, the reliability problem of the SFC in both the building and mapping must be considered.

In the construction research of the SFC, only a single service request scenario is discussed, and the overall consideration and optimization for a plurality of SFCs are not considered. In the mapping research of the SFC, the mapping of the SFC is completed by minimizing the cost, the resource consumption and the like, but the end-to-end delay constraint is not considered, and the reliability of the SFC is not researched in the mapping process.

Disclosure of Invention

In view of this, the present invention provides a method for reliably constructing and deploying a service function chain in a network slice scenario, so as to solve the problem of constructing and mapping multiple SFCs on the premise of ensuring reliability, and effectively reduce network resource consumption and overall service cost.

In order to achieve the purpose, the invention provides the following technical scheme:

a method for reliably constructing and deploying a service function chain in a network slice scene comprises the following steps:

s1: in a network slicing scene, reliably constructing service function chains SFC under a plurality of service requests, constructing service function graphs SFG by adopting an SFC reliable construction algorithm based on a shared virtual network function VNF through the dependency relationship and sharable times of the VNF, calculating and selecting the SFG with the highest reliability through a repulsion principle, and completing the construction of the SFC of the plurality of network slicing service requests;

s2: the method comprises the steps of reliably mapping the SFG based on the construction result of the SFG, adopting an SFG mapping algorithm based on delay perception and reliability, mapping and backing up VNFs in the SFG to meet the reliability requirement of a user, and searching the optimal solution of a mapping scheme in polynomial time by using a heuristic algorithm based on node importance.

Optionally, in S1, the network slice scene includes: the network function virtualization management system comprises an infrastructure layer, a virtual network function layer, a service operation support system, a network function virtualization management and orchestration NFV MANO and a Software Defined Network (SDN) controller; the SFC is formed by connecting a specific set of VNFs by virtual links and is deployed at a virtual network function layer;

the SFC build problem is to group VNFs into SFGs for multiple network service requests.

Optionally, in S1, based on the reliable SFC construction algorithm of the shared VNF, with the objective of minimizing resources required by the network slicing service request and maximizing SFG reliability as an optimization goal, the SFC under multiple service requests is constructed as an SFG according to the dependency relationship and the number of sharing times, which specifically includes:

s11: initializing the SFG set as an empty set;

s12: constructing an SFC set for each service request, carrying out full arrangement on VNFs contained in the service request, and obtaining the SFC set by deleting the VNF sequences which do not meet the dependency relationship;

s13: for each SFC, constructing an SFG according to the sharing times requirement of the VNF;

s14: adding the current SFG to the SFG set;

s15: updating the SFG set by using the current SFG until each service request is processed;

s16: and for each SFG in the constructed SFG set, calculating the reliability of the SFG by using a repulsion principle, and selecting the SFG with the highest reliability as a construction result of the SFC construction under a plurality of service requests.

Optionally, in S2, based on the delay-aware and reliable SFG mapping algorithm, minimizing the physical node activation cost, the VNF deployment cost, and the traffic forwarding cost as optimization targets, and using a heuristic algorithm based on node importance for delay-aware and reliable SFG mapping specifically includes:

s21: the total initialization cost is 0;

s22: for the first service request, mapping and backing up VNF instances in the SFG according to the node importance;

s23: calculating the shortest path from the source node to the destination node, so that the VNF can meet the delay requirement of the service request after being mapped;

s24: calculating node resources and physical link resources used by the mapped VNF in the physical network;

s25: updating the node resources in the physical network and the residual capacity of the physical link;

s26: calculating a service request cost and adding to a total cost; the service request cost comprises physical node activation cost, VNF deployment cost and traffic forwarding cost;

s27: if all VNFs in the SFC have been mapped and meet the capacity requirement, repeating steps S23-S26;

s28: if the current VNF capacity is insufficient, the same VNF or a new VNF type needs to be mapped, VNF instances in the SFG are mapped and backed up according to the node importance degree, and the steps S23-S26 are repeated until each service request is processed;

the node importance is jointly determined by the near centrality and the node reliability of the complex network analysis.

The invention has the beneficial effects that: the invention provides an SFC reliable construction algorithm based on a shared VNF aiming at the overall consideration and optimization of a plurality of SFCs, and provides an SFG mapping algorithm based on delay perception and reliability by considering end-to-end delay constraint and SFC mapping reliability, so that the network resource consumption and the overall service cost are effectively reduced on the premise of ensuring the SFC reliability in a network.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an overall process of an SFC reliable construction algorithm based on a shared VNF;

fig. 2 is an overall flow of the SFG mapping algorithm based on delay perception and reliability.

Detailed Description

The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.

Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.

The physical network of the invention comprises a plurality of service functions carried on physical infrastructure and uses undirected graph G^pWhere N denotes a set of physical nodes, L denotes a set of physical links connecting the physical nodes, and each physical node N_ie.N for containing limited physical resources (CPU resources, memory space, etc.)

Representing, each physical node n_iFor hardware reliability of e N

And (4) showing. Each physical link (n)_i,n_j) e.L containing limited bandwidth resources

And (4) showing. Physical network resources may create a virtual network through virtualization, and multiple service requests may be carried on one physical node.

Virtual network representation as undirected graph G^vAnd (V, E), wherein V denotes a set of VNFs instantiated on the virtual machine, and E denotes a set of virtual links connecting the VNFs in the virtual network. Each VNfv_iEpsilon V can be represented as a triplet

Wherein the content of the first and second substances,

denotes v_iThe virtual resource of (2) is selected,

denotes v_iThe reliability of the software itself,

denotes v_iThe maximum number of shares. Each virtual link (v)_i,v_j) E connecting any two VNFvs through physical link_iAnd v_jWith a reliability of

When v is_iAnd v_jAll reliable, virtual link (v)_i,v_j) Is reliable and therefore has

The set of network slice service requests is denoted as Q, and a single service request may be denoted as a quintuple

Wherein, V_i ^qRepresenting the ordered set of VNFs required in the request,

representing the dependency between the VNFs and,

denotes q_iBandwidth requirement of, T_i ^qDenotes q_iThe maximum allowed time delay of the time delay,

denotes q_iThe reliability requirements of. In that

In the use of d_jDenotes v_jOf (d), i.e. { d_j|v_j∈V_i ^qIf v is₂Dependence on v₁Then d is₁＞d₂I.e. v₁Has a dependency level higher than v₂(ii) a If v is₁ v₂The dependency levels are the same, then d₁＝d₂Thereby specifying the order of connection between VNFs when constructing the SFC.

The mapping relationship between the VNF and the underlying physical network in the virtual network may be made of a binary variable

Indicating, i.e. for service requests q_i∈Q，v_iMapping e to V_jWhen the element belongs to the N, the element is selected,

otherwise

Deployment to physical node n based on VNF software reliability and physical node hardware reliability_jVNF instance v of (c)_iIs defined as

Can be expressed as:

in the SFC reliable construction algorithm based on the shared VNF, one SFG consists of a plurality of SFCs, the reliability of the whole SFG is jointly determined by the reliability of each VNF, and meanwhile, the reliability of each SFC is also influenced. Ideally, when the reliability of the SFG is 1, all the links it contains can provide stable service between two terminals. Therefore, the reliability of the constructed SFC can be guaranteed as much as possible by constructing and selecting the SFG with high reliability for subsequent network mapping.

For a service request set Q ═ Q_iSame dependency relationship

Corresponding to different SFGs, constructing the SFCs on the basis of sharing the VNF, and forming a plurality of SFCs into an SFG set G^q＝{t_m(. o) }, in which t_m(. cndot.) denotes that the mth has reliability

The SFG of (1). The size of each SFG set can be expressed as:

wherein, | · | represents a set · the number of elements contained, S_iRepresenting all cases of SFC generated by the jth service request.

Calculating reliability of mth SFG by using repulsion principle

Can be expressed as:

wherein Pr (·) represents the edge failure probability, C_iRepresents the ith minimal edge cut set, k is the number of minimal edge cut sets, N_iIs represented by C_iThe point, σ (N), to which the edges included in (A) are connected_i) Represents N_iIs determined. Thus, if C₁＝{(v₁,v₂),(v₁,v₃) }, then

Then to G^qThe elements in (1) are subjected to reliability evaluation, and the most reliable SFG is selected for subsequent backup and mapping. The goal of the model herein is to maximize VNF instance sharing, i.e. minimize the resources required for network slice service requests while selecting the SFG with the highest reliability. The objective function and constraints are as follows:

s.t.

wherein the SFG set is constructed with the goal of minimizing resource consumption and maximizing SFG reliability under the C1 and C2 constraints. C1 denotes the share times constraint, for any v in all service requests_iCannot exceed its sharing times. C2 represents a dependency constraint, for any service request q_jIf v is_lDependence on v_kThen v is_kWith a higher level of dependency.

Referring to fig. 1, fig. 1 is an overall flow of an SFC reliable construction algorithm based on a shared VNF. Firstly, initializing an SFG set as an empty set, using an SFC construction algorithm based on a dependency relationship for each network slice service request, and constructing the SFC set according to the dependency relationship. And initializing an empty set as the current SFG, aggregating each SFC with the existing SFG and adding the aggregated SFG into the current SFG according to the sharing frequency requirement of the VNF, and finally updating the SFG set by using the current SFG set.

SFG set G can be obtained through the algorithm^q＝{t_m(. -) reliability of each SFG Using the principle of repulsion

Evaluating and selecting

Highest SFGt_m(. to) perform subsequent network mapping.

In the SFG mapping algorithm based on delay perception and reliability, in the SFG mapping process, the VNFs in the main SFG and the backup SFG are placed in the optimal bottom-layer physical network, so that the end-to-end delay requirement of a network slicing service request is met, and the overall service cost is reduced to the maximum extent.

Since the underlying physical network is irregular in nature, the impact of the underlying physical node, node n, can be described using the proximity center (CC) in a complex network analysis_iNear centrality CC of_iCan be expressed as:

wherein d (i, j) represents the node n_iTo node n_jThe shortest distance therebetween. To ensure reliable mapping of SFG, CC and node reliability are jointly considered to describe the importance of the bottom layer physical node, i.e. the importance of the bottom layer physical node

Can be expressed as:

to formally describe the SFG mapping process, the following binary decision variables will be defined.

Representing a physical node n_iE.n is active, otherwise

Representing a virtual node v_iDeploying the element V at a physical node n_jE.g. N, otherwise

Representing virtual backup nodes

Deployed at physical node n_jE.g. N, otherwise

Representing a request for service q_iE.g. Q, virtual node v_iMapping e to V to physical node n_jE is N, otherwise

Representing a request for service q_iE.g. Q, virtual backup node

Mapping to a physical node n_jE.g. N, otherwise

Representing a request for service q_iE.g. Q, virtual link (v)_k,v_l) e.E mapping to physical link (n)_i,n_j) E.g. L, otherwise

Representing a request for a service q_iE.g. Q, virtual backup link

Mapping to physical link (n)_i,n_j) E is L, otherwise

The objective of the delay-aware and reliable SFG mapping algorithm is to reduce the overall service cost generated in the SFG mapping process as much as possible, so the objective function consists of the following three parts:

physical node activation cost: including the design, deployment, and maintenance costs of the physical network, can be expressed as:

wherein, c_nRepresenting the activation cost of the physical node.

VNF deployment cost: the mapping cost, including the primary VNF and the backup VNF, may be expressed as:

wherein, c_nvRepresenting the deployment cost of the VNF instance.

Traffic forwarding cost: the cost required to forward a traffic flow from one physical node to another, the bandwidth (in Mbps) consumed to forward traffic over a link, and the co-determination between nodes, can be expressed as:

wherein, c_nnRepresents the cost required to forward the traffic flow between the physical nodes,

representing a physical link (n)_i,n_j) E L.

The objective function is therefore to minimize the sum of the above costs, namely:

P:min(α₁P₁+α₂P₂+α₃P₃)

wherein alpha is₁、α₂、α₃Each representing a weighting factor for the above costs, and a₁+α₂+α₃＝1。

For the objective function, the following constraints will be applied:

resource constraint: the resource requirements of the SFC deployed on the physical network should not exceed the available resources of the physical nodes and links.

Wherein, the first and the second end of the pipe are connected with each other,

representing a service request q_iThe required processing capacity of the processing means is,

representing VNfv_iThe processing power of (1).

And (3) delay constraint: the overall delay of each SFC in the SFG should be less than or equal to the maximum allowed delay requirement for the service request.

Wherein the content of the first and second substances,

denotes v_iThe processing delay of (1).

And (3) flow restriction: for each physical node n_iAt each service request q_iIn n, is placed in_iVirtual node v of_kAnd v_lAll incoming and outgoing traffic of the virtual links in between should be equal.

Primary backup mapping constraint: the main VNF and the backup VNF are not mapped on the same physical node at the same time, so that the SFG can still normally operate when the main VNF fails.

Other constraints are: and (4) deciding constraint relations among variables.

Wherein C10 represents n_jIs activated when at least 1 VNF is deployed, C11 and C12 represent service requests q_iV. of (1)_iShould be mapped at physical node n_jTo complete the mapping of the SFC.

Referring to fig. 2, fig. 2 is an overall flow of the SFG mapping algorithm based on delay perception and reliability. The total cost is initialized to 0, and for the first service request, VNF instances in the SFG are mapped and backed up according to the node importance. Then, the shortest path from the source node to the destination node is calculated to meet the delay requirement of the service request, the remaining resources of the physical node and the link are calculated and updated, and meanwhile, the service request cost (physical node activation cost, VNF deployment cost and traffic forwarding cost) is calculated and added to the total cost. If all VNFs in the SFC have been mapped and meet the capacity requirement, their latency requirement, remaining resources and total cost of service requests are calculated directly. If the current VNF capacity is insufficient, the same VNF or a new VNF type needs to be mapped, VNF instances in the SFG are mapped and backed up according to the node importance, and the delay requirement, the residual resources and the total cost of the service request are calculated until each service request is processed.

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims (4)

1. A method for reliably constructing and deploying a service function chain in a network slice scene is characterized by comprising the following steps: the method comprises the following steps:

s1: in a network slicing scene, reliably constructing service function chains SFC under a plurality of service requests, constructing service function graphs SFG by adopting an SFC reliable construction algorithm based on a shared virtual network function VNF through the dependency relationship and sharable times of the VNF, calculating and selecting the SFG with the highest reliability through a repulsion principle, and completing the construction of the SFC of the plurality of network slicing service requests;

s2: the method comprises the steps of reliably mapping the SFG based on the construction result of the SFG, adopting an SFG mapping algorithm based on delay perception and reliability, mapping and backing up VNFs in the SFG to meet the reliability requirement of a user, and searching the optimal solution of a mapping scheme in polynomial time by using a heuristic algorithm based on node importance.

2. The method for reliably constructing and deploying the service function chain in the network slice scenario according to claim 1, wherein: in S1, the network slice scene includes: the network function virtualization management system comprises an infrastructure layer, a virtual network function layer, a service operation support system, a network function virtualization management and orchestration NFV MANO and a Software Defined Network (SDN) controller; the SFC is formed by connecting a specific set of VNFs by virtual links and is deployed at a virtual network function layer;

the SFC build problem is to group VNFs into SFGs for multiple network service requests.

3. The method for reliably constructing and deploying the service function chain in the network slice scenario according to claim 1, wherein: in S1, based on the reliable SFC construction algorithm of the shared VNF, with the objective of minimizing resources required by the network slicing service request and maximizing SFG reliability as optimization, the SFC under multiple service requests is constructed as an SFG according to the dependency relationship and the number of sharing times, which specifically includes:

s11: initializing the SFG set as an empty set;

s12: constructing an SFC set for each service request, carrying out full arrangement on VNFs contained in the service request, and obtaining the SFC set by deleting the VNF sequences which do not meet the dependency relationship;

s13: for each SFC, constructing an SFG according to the sharing times requirement of the VNF;

s14: adding the current SFG to the SFG set;

s15: updating the SFG set by using the current SFG until each service request is processed;

s16: and for each SFG in the constructed SFG set, calculating the reliability of the SFG by using a repulsion principle, and selecting the SFG with the highest reliability as a constructed result of the construction of the SFC under a plurality of service requests.

4. The method for reliably constructing and deploying the service function chain in the network slice scenario according to claim 1, wherein: in S2, based on the delay-aware and reliable SFG mapping algorithm, minimizing the physical node activation cost, VNF deployment cost, and traffic forwarding cost as optimization objectives, and using a heuristic algorithm based on node importance for delay-aware and reliable SFG mapping specifically includes:

s21: the total initialization cost is 0;

s22: for a first service request, mapping and backing up VNF instances in the SFG according to the node importance;

s23: calculating the shortest path from the source node to the destination node, so that the VNF can meet the delay requirement of the service request after being mapped;

s24: calculating node resources and physical link resources used by the mapped VNF in the physical network;

s25: updating the node resources in the physical network and the residual capacity of the physical link;

s26: calculating a service request cost and adding to a total cost; the service request cost comprises physical node activation cost, VNF deployment cost and traffic forwarding cost;

s27: if all VNFs in the SFC have been mapped and meet the capacity requirement, repeating steps S23-S26;

s28: if the current VNF capacity is insufficient, the same VNF or a new VNF type needs to be mapped, VNF instances in the SFG are mapped and backed up according to the node importance degree, and the steps S23-S26 are repeated until each service request is processed;

the node importance is jointly determined by the near centrality and the node reliability of the complex network analysis.

Images