Service provisioning in a communication network

This application claims priority under 35 U.S.C. § 119 or 365 to European Patent Application No. 15177503.8, filed Jul. 20, 2015. The entire teachings of the above application are incorporated herein by reference.

The present invention relates to service provisioning in a communication network. More in particular, the present invention relates to allocating virtual network functions and virtual network paths of a desired service to a physical communication network comprising physical network nodes and physical network links, where the allocating is carried out subject to constraints.

In communication networks it is well known to use service requests which specify a service required from the network. A service request may include a source, a destination, a certain bandwidth, a certain quality of service and/or other parameters. The network attempts to accommodate the service request by making the requested resources available. Often, many alternative resources, such as parallel paths, are available to accommodate a requested service. Thus, a network service corresponding to a particular service request may have several alternative implementations.

The resources to be utilized by a service may be subject to constraints. A particular network service may, for example, require a certain minimum bandwidth, which imposes a bandwidth constraint. For safety and security reasons, services may be required to share a certain resource in a network node, or may be required not to share a resource.

In traditional networks, the functionality of a network node is coupled with a physical device and, hence, the establishment of a network service involves setting up physical devices, their connections and configuration. If demand changes for an existing service, or if a new service is demanded, the network operator may be required to add or remove devices from the network to increase or decrease the capacity or functionality if the existing devices cannot meet the demanded change.

Network Functions Virtualization (NFV) is a method to decouple network functions, for example router, firewall, application layer gateway, a virus scanner, from the physical device by using virtualization technologies, such as VMware. Virtualization enables physical devices to be regarded as resources on which network functions can be loaded dynamically. For example, when a network service is required to filter traffic at a certain location in a network, NFV allows for the allocation of a firewall network function to a multi-purpose device (for example, a device hosted in a cloud datacenter).

A service can be described as a Service Function Chain (SFC). An SFC defines a set of one or more network functions of a service and ordering constraints for the functions through which data packets are exposed.

ETSI Draft Specification GS-NFV-MAN V0.6.1, “Network Function Virtualization (NFV): Management and Orchestration” (2014-07) describes the management and orchestration framework required for provisioning virtualized network functions and related operations. One scenario that is described in the ETSI Draft Specification is that virtual network functions can be chained to other virtual network functions and/or physical network functions to realize a network service.

Virtual network functions and virtual network paths may be used to deploy network services independently from their physical implementations. When specifying a network service in terms of virtual network functions and virtual network paths, those functions and paths have to be allocated to their physical counterparts. Two or more virtual network functions may be collocated, that is, implemented in the same physical resource (for example, two virtual switches may be collocated in a single physical node). Alternatively, two or more virtual network functions may be non-collocated, that is, implemented in different physical resources (for example, two virtual switches may be non-collocated in two distinct physical nodes).

The paper by Espling et al., “Modeling and placement of structured cloud services”, Transactions on Network and Service Management, 2013, discloses a method of using affinity constraints and anti-affinity constraints for the allocation of cloud services. Affinity constraints, also known as co-location constraints, indicate that services or service items should share a common resource, such as a node. Anti-affinity constraints indicate that services or service items should not share a common resource but should use alternative resources instead. Such constraints may for example indicate that services should not use a node in a certain country, and/or should use a certain node in the home country.

The method disclosed in Espling's paper focuses on constraints in nodes, avoiding co-location of services on the same node, for example. The use of affinity constraints and anti-affinity constraints allows a very clear definition of certain constraints, in particular constraints relating the sharing, or not sharing, of resources. However, this known method is limited in scope and only deals with network nodes.

It is often desired to specify that virtual network paths should not share a common physical path, for example to increase the reliability of a network service or to deal with bandwidth limitations. Similarly, it is also often desired to specify that virtual network paths should share a common physical path, for example for security or efficiency reasons. Prior art methods fail to provide a simple and effective manner to achieve this.

It is an object of the present invention to solve this problem by providing a method which allows services to be provisioned while allowing more specific constraints to be taken into account.

It is a further object of the present invention to provide a method which may be used in network function virtualization (NFV) environments, in particular service function chain (SFC) service descriptions.

Accordingly, the present invention provides a method of provisioning a service in a communication network, the service comprising:

at least one virtual network function, and

at least one virtual network path,

which at least one virtual network function and at least one virtual network path are to be implemented in the communication network,

which method comprises:

obtaining affinity constraints and/or anti-affinity constraints relating to mapping the at least one virtual network path onto the communication network, and

mapping the at least one virtual network function and at least one virtual network path onto the communication network subject to said constraints.

By using affinity constraints and anti-affinity constraints for paths, instead of only for nodes as in the prior art, such constraints can be used more generally in the network. More in particular, affinity constraints and anti-affinity constraints may, in accordance with the present invention, be used for virtual network functions and virtual network paths in general and concern for example locations such as data centers, countries, regions etc. in addition to, or instead of, network nodes.

In accordance with the present invention, it can be specified whether paths should be mapped onto resources which are collocated (collocated virtual network paths) or whether they should be mapped onto resources which are not collocated (non-collocated virtual network paths), wherein collocated may imply sharing a datacenter, a country, a region, etc. By mapping the virtual network functions and virtual network paths onto the communication network subject to the affinity and/or anti-affinity constraints which may relate both to functions and to paths, the colocation of virtual network paths can be enforced or avoided. Similarly, the colocation of virtual network functions can be enforced or avoided.

Although the service may include only a single virtual network function, typically services will include two or more network functions. The at least one virtual network path can connect at least two virtual network functions, or at least one network function and a terminal, such as a user terminal. Some services may include two or more terminals, for example a source terminal and a destination terminal.

It is noted that affinity constraints can define colocation and that anti-affinity constraints can define non-colocation of network resources, such as virtual network functions and virtual network paths.

The step of obtaining affinity constraints and/or anti-affinity constraints may comprise retrieving said constraints from a memory, for example from a semiconductor memory of a network controller, in which a policy may be stored. The affinity and/or anti-affinity constraints and the associated policy may be previously stored in memory by a system operator or by a user, or by a processor arranged for determining constraints on the basis of network properties and/or system operator and/or user specifications. In such embodiments, the affinity constraints and/or anti-affinity constraints are provided separately from the service requests. In some embodiments, the affinity constraints and/or anti-affinity constraints can be included in a service request.

Advantageously, the method according to the present invention may further comprise:

obtaining affinity constraints and/or anti-affinity constraints relating to mapping the at least one virtual network function onto the communication network, and

mapping the at least one virtual network function and at least one virtual network path onto the communication network subject to said constraints.

Accordingly, the affinity constraints and/or anti-affinity constraints may not only relate to mapping the at least one virtual network path onto the communication network, but also to mapping the at least one virtual network function onto the communication network, and the mapping may be carried out taking both any constraints relating to mapping the at least one virtual network path and any constraints relating to mapping the at least one virtual network function into account.

In an advantageous embodiment, the service is defined in a service request and the step of mapping the at least one virtual network function and the at least one virtual network path onto the communication network may comprise:

producing a network model representing the network resources, the network model comprising a resource topology,

producing a request model by using the service request, the request model comprising a request topology,

producing a set of matches between the resource model and the request model, subject to the affinity constraints and the anti-affinity constraints,

selecting a best match from the set of matches by using an optimization, and

allocating network resources to the best match.

By producing both a network model representing the available resources and a request model representing the requested resources, the requested resources can easily be compared with the available resources.

By using the affinity constraints and anti-affinity constraints to produce a set of matches, only feasible and desired matches are produced.

By using an optimization for selecting a best match, an objective criterion can be used for the best match from the set of matches.

By allocating nodes and paths to the best match, an optimal allocation of the requested service to the available resources is achieved, subject to the affinity constraints and anti-affinity constraints.

In an embodiment, the step of producing a network model comprises gathering current allocations of physical nodes and physical paths in the network.

The step of producing a network model may comprise modelling at least one of node resources, path resources, and quality of service. Similarly, the step of producing a request model may comprise modelling at least one of virtual function resources, virtual path resources, and quality of service.

Although the affinity constraints and anti-affinity constraints may be used directly, it is preferred that the step of producing the set of matches comprises translating the affinity constraints and anti-affinity constraints into optimization constraints. In an embodiment, therefore, the step of producing the set of matches comprises using integer linear programming (ILP) constraints representing the affinity constraints and anti-affinity constraints. That is, the affinity constraints and anti-affinity constraints are in such an embodiment translated into ILP constraints which can then be used in the optimization procedure.

Although various types of service requests may be used, the present invention is particularly suitable for service requests of the service function chain (SFC) type. A service can be described as a service function chain consisting of a set of virtual network functions, which may be connected in an acyclic graph structure. SFC type services are known per se and typically use an SFC template. In prior art SFC templates, certain requirements such as efficiency or security cannot be specified. By extending existing SFC templates with affinity and/or anti-affinity constraints, this problem is solved.

It is noted that by using network function virtualization (NFV) techniques, which are also known per se, network functions may be decoupled from the physical devices supporting these functions. It is further noted that the actual mapping of virtual functions and/or virtual paths onto physical nodes and/or physical paths can be determined by binary variables.

The present invention further provides a software program product for allowing a processor to carry out the method defined above. The software program product may be stored on a tangible carrier, such as a DVD or a USB stick. Alternatively, the software program product may be stored on a server from which it may be downloaded using the Internet. The software program product contains software instructions which can be carried out by the processor of a device, such as a server, a user device (for example a smartphone), and/or a monitoring device.

The present invention additionally provides a system for provisioning a service in a communication network, the service comprising:

at least one virtual network function, and

at least one virtual network path,

which at least one virtual network function and at least one virtual network path are to be implemented in the communication network,