Institute of Communications and Connected Systems


5G Core functions

This page is part of the output from the Institute of Communications and Connected Systems that  presents aspects, components, and testbeds which are part of the challenge for 5G infrastructures.

In particular, this page covers the 5G Core functions, required for the main functionality of a 5G platform:

1. Service Infrastructure instantiation
2. Some Orchestration functions
3. Monitoring
4. Information Systems facilities


The following acronyms are used throughout these pages:

DC                   Data Center
IA                     Infrastructure Adaptor
NFVI                Network Function Virtualization Instantiator
MCE                Management and Control Entity
NIM                 Network Infrastructure Manager
PoP                 Point of Presence
REST              Representational State Transfer
SDN                Software Defined Networking
SFC                 Service Function Chaining
VIM                  Virtual Infrastructure Manager
VNF                 Virtual Network Function
WIM                 Wide Area Network Infrastructure Manager
VM                   Virtual Machine

1. Service Infrastructure instantiation

This section describes the Infrastructure Adaptor (IA), an abstraction layer that isolates and wraps the vendor-specific functionality of a virtualised infrastructure (NFVI), which offers virtual resource such as computational, network and storage, providing an abstract interface to operate on them for the overlying orchestration and management entities of the 5G environment, such as MANO or Network OS or other management entities.

The IA allows orchestrator and management entities to interact with the underlying virtual infrastructure, regardless of the specific technology used to manage it. It exposes interfaces to manage virtual network services and VNF instances, retrieve basic monitoring information about the infrastructure status, reserve resources for services deployment. It is composed of two main modules, the Virtual Infrastructure Manager Adaptor (VIM Adaptor) and the WAN infrastructure Manager Adaptor (WAN Adaptor).

The VIM Adaptor is responsible for exposing an interface to interact with one or more VIMs, managing computational, network or storage resource in one or more NFVI- Points of Presence. It enables the interaction between the overlaying entities and one or more VIMs. Using specific wrappers for different VIM implementations, the VIM Adaptor exports a common interface to the overlaying entities to manage computational and storage resource, deploy and manage services, provide necessary instance information for the monitoring and management facilities of the service platform. The module is conceptually divided in two parts.

The upper part of the VIM Adaptor realizes the interface toward the service platform, exposing the API described above through the message bus. The use of queues and of the multiplexer/de-multiplexer system enables the asynchronous handling of multiple API calls, as shown in the following Figure 2.

Call processors, which implement procedure for the different API calls, act as a conceptual border between the two parts of the VIM adaptor. The lower part of the VIM adaptor is responsible for the actual interaction with the VIMs. Its architecture is sketched in Figure 2.

Each wrapper implements internally the needed procedure to serve the API calls using the VIM it wraps, such as translating the virtual service or VNF manifests in VIM-specific description language, interact with the relevant endpoint for the deployment, manage the instances. Although the design is completely vendor agnostic, the current version of the VIM Adaptor allows registering and interacting with OpenStack, assuming the availability of a Heat endpoint to deploy service in an orchestrated fashion. Future works will extend the set of available VIMs, introducing more wrappers.

The WIM Adaptor allows managing network resources in the WAN connecting different NFVI-PoPs in a vendor agnostic fashion, in order to provide connectivity to the deployed services. It follows the functionalities offered by the VIM adaptor, solely focusing on the abstraction of the network towards. As such the main functions, implemented by the WIM adaptor are:

  • WIM Abstraction: Exposes an interface to the MANO framework that is technology agnostic to the underlying southbound interfaces or functionalities. The API exposes methods for network service deployment, WIM status and resource management. Depending on the underlying supported functionalities, additionally, network isolation and splitting features may be supported.
  • Topology and resource discovery: The WIM Adaptor exposes collected information on WAN topology, network resource availability and infrastructure status.

The IA has been designed and developed in the framework of the SONATA 5G-PPP Project. The module is open source, it is licensed under Apache 2.0 license and it counts 224 classes and 17K lines of code. It comes packaged into a Docker container that can be automatically built and started using Docker. Code available at https://github.com/DarioValocchi/son-sp-infrabstract


1.     H. Karl, S. Dräxler, M. Peuster, A. Galis, M. Bredel, A. Ramos, J. Martrat, M. S. Siddiqui, S. van Rossem, W. Tavernier, G. Xilouris "Development and Operations (DevOps) for Network Function Virtualization" - Wiley Transactions on Emerging Telecommunications Technologies; — August 2016 http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2161-3915

2.     Rubio-Loyola, J., Galis, A., Astorga, A., Serrat, J., Lefevre, L., Fischer, A., Paler, A., de Meer, H., "Scalable Service Deployment on Software Defined Networks"—IEEE Communications Magazine/ Network and Service Management Series, ISSN: 0163-6804; December 2011; http://dl.comsoc.org/ci1/

3.     Rochwerger, J. Caceres, R. Montero, D. Breitgand, A. Galis, E. Levy, I. Llorente, K. Nagin, Y. Wolfsthal "The RESERVOIR Model and Architecture for Open Federated Cloud Computing", the IBM System Journal Special Edition on Internet Scale Data Centers, vol. 53, no. 4, 2009, http://www.haifa.ibm.com/dept/stt/sas_public.html, http://academic.research.microsoft.com/Paper/5112741.aspx

4.     B. Rochwerger, A. Galis, E. Levy, J. A. Cáceres, D. Breitgand, Y. Wolfsthal, I. M. Llorente, M. Wusthoff, R. S. Montero, E. Elmroth "RESERVOIR: Management Technologies and Requirements for Next Generation Service Oriented Infrastructures"- 11th IFIP/IEEE International Symposium on Integrated Management 1-5 June 09, New York, USA, http://www.ieee-im.org/2009/

2. Some Orchestration functions

This section describes some of the many Orchestration functions that are needed in a 5G environment. Orchestration lies at the core of the 5G softwarized network architecture. I can be seen architectural element with the function of mapping services to connectivity, computing, and storage resources and processing service instantiation requests to generate a resource mapping. It also manages the service lifecycle (deployment, operation, modification, termination), supports isolation and policing between different virtual services, and virtual service providers. The ETSI NFV infrastructure description does not define orchestration explicitly. It concentrates orchestration functionality in the Functions Virtualisation Orchestrator (NFVO) functional block, that manages the network service lifecycle and coordinates the management of network service lifecycle, VNF lifecycle (supported by the VNFM) and NFVI resources (supported by the VIM) to ensure an optimized allocation of the necessary resources and connectivity. This model implies a single concentrated functional block, without delegation, but its functionality can be split to obtain a more modular functional description. A non-exclusive list of these functionality is:

  • VNF Placement: allow the customer to deploy VNFs at arbitrary points into the network and set where the components/ gateways will be placed on the operator network. For example, deploy a VNF as near as possible to a specific location or select were the VNF will be deployed.
  • SFC: Service chaining: allow the customer to interconnect VNFs in an arbitrary graph.
  • Service Chaining Support Across Wide Area Networks: support service function chains that include service functions separated by a wide area network, e.g. across different data centres, or between the core data centre and an edge cloud.
  • Abstract Programming Model: provide abstract programming models and interfaces for network services, which enable a high level of automation in service development and deployment processes.
  • Multi NFVI orchestration: orchestrate multiple VNF execution environments (NFVI-PoPs) located in arbitrary places in the operator network topology. The NFVI-PoPs are considered to be controlled and managed by VIMs.
  • Lifecycle Management: deal with triggering (groups of) VM start-up, shutdown, pause, etc. actions in the actual infrastructure; contextualizing VNFs/services via actions provided by the service manifests.
  • Placement and Scaling: execute algorithms that place and scale a running service, both at start-up and continuously (e.g., when load goes up).
  • Integration with existing VNFs or components: allow components or VNFs of a new service to be integrated with existing services, VNFs or system components (such as Legacy Physical Network Function).

There are Orchestration functions as part of the UCL VLSP open source soft infrastructure testbed. It can be downloaded from our UCL EE CISP repository http://clayfour.ee.ucl.ac.uk/usr/. Currently VLSP has over 550 classes and over 100K lines of code.


5.     Chapman, C., Emmerich, E., Marquez, F. G., Clayman, S., Galis, A. - "Software Architecture Definition for On-demand Cloud Provisioning"- Springer Journal on Cluster Computing — DOI: 10.1007/s10586-011-0152-0; May 2011; http://www.editorialmanager.com/clus/; on line: www.springerlink.com/content/m31np5112525l67v/

6.     Galis, H. Abramowicz, M. Brunner, D. Raz, P. R. Chemouil, J. Butler, C. Polychronopoulos, S. Clayman, H. de Meer, T. Coupaye, A. Pras, K. Sabnani, P. Massonet, S. Naqvi "Management and Service-aware Networking Architectures (MANA) for Future Internet Position Paper: System Functions, Capabilities and Requirements"- Invited paper IEEE 2009 Fourth International Conference on Communications and Networking in China (ChinaCom09?) 26-28 August 2009, Xi'an, China, http://www.chinacom.org/2009/index.html

7.     S. Clayman, L. Mamatas, A. Galis "Energy-efficiency Enablers and Operations in Software-Defined Environments" - Management of 5G Networks Workshop at IEEE NOMS 2016, 25-29 April 2016, Istanbul, Turkey - http://noms2016.ieee-noms.org

8.     C. Chapman, W. Emmerich, F. Galn, S. Clayman, A. Galis "Elastic Service Management in Computational Clouds", 12th IEEE/IFIP Network Operations and Management Symposium (NOMS2010) / International Workshop on Cloud Management (CloudMan 2010) 19-23 April 2010, Osaka http://cloudman2010.lncc.br/

9.     Femminella, M; Reali, G; Valocchi, D.; "Genome Centric Networking: a network function virtualization solution for genomic applications", Accepted for publication on 2017 IEEE Conference on Network Softwarization (NetSoft).

3. Monitoring

This section describes a dynamic and flexible monitoring platform that can be used in virtualized environments. The monitoring of 5G environments needs to encompass live run-time data for the following: physical and virtual resources; network and DC slices; orchestration; services; SLA; energy consumption; dynamic reconfiguration of monitoring system; further data processing / aggregation / time windows; et al.

The Lattice Monitoring Framework provides functionality to add powerful and flexible monitoring facilities to systems. Lattice has a minimal runtime footprint and is not intrusive, so as not to adversely affect the performance of the system itself or any running applications. The monitoring can be built up of various components provided by the framework, so creating a bespoke monitoring sub-system.

The framework provides Data Sources and Data Consumers (respectively producers and consumers of monitoring data distributed via a network — data plane) as well as a Control System. The Control System implements and exposes (through a RESTful northbound API) mechanisms to dynamically load and/or configure the monitoring components at run-time (e.g., starting and activating/deactivating new probes, tuning the probe sending data rate, adding a new reporting mechanisms to allow further data processing/aggregation, etc.) by sending control messages on the dedicated control plane and without the need of restarting the running monitoring elements.

These functionalities can be used by the upper level management entities of the system to build and configure on demand the required monitoring sub-system as well as enforcing specific policies on it according to the system run-time conditions. This turned out to be important on multi-technological-domain environments, where different monitoring elements are required to collect data from heterogeneous type of resources that are known only at the time of instantiation of a network service. The Lattice Control System in fact exposes to the service and resource orchestration layers the proper mechanisms to deploy and configure the required monitoring blocks according to the desired data aggregation policies, even across the service providers’ administrative boundaries.

Furthermore, in such large distributed systems there may be hundreds or thousands of measurement probes which can generate data. It would not be effective to have all of these probes sending data all of the time. The Control System provides mechanisms needed to control and manage the selective activation of relevant probes, adjust the related measurements sending rate and dynamically changing the propagation of the data monitoring flow according to the network services being deployed.

Lattice has been utilized within the RESERVOIR, UniverSELF, DOLFIN, and 5GEx projects. In those scenarios, monitoring is a vital part of the full control loop that goes from the service management, through a control path, to the probes which collect and send data, back to the service management which makes various decisions based on the data. The monitoring is a small but fundamental part of the system as it allows the integration of components in all of the layers as it is used by the infrastructure itself and by different resource slices, as well as for service management and SLA verification.

Lattice consists of about 350 Java classes and 40K lines of code. The Lattice framework can be downloaded from http://clayfour.ee.ucl.ac.uk/lattice/index.html


10.  Clayman, S., Clegg, R., Mamatas, L., Pavlou, G., Galis, A.: "Monitoring, Aggregation and Filtering for Efficient Management of Virtual Networks"— IEEE CNSM mini-conference 2011: 7th International Conference on Network and Service Management www.cnsm2011.org/ - October 2011, Paris, France http://cnsm.loria.fr/

11.  S. Clayman, A. Galis, G. Toffetti, L. M. Vaquero, B. Rochwerger, P. Massonet "Future Internet Monitoring Platform for Computing Clouds"- ServiceWave 2010, December 2010, http://servicewave.eu/2010/joint-demonstration-evening/ and in "Towards A Service-Based Internet" Lecture Notes in Computer Science, 2010, Volume 6481/2010, 215-217, DOI: 10.1007/978-3-642-17694-4_30

12.  S. Clayman, A. Galis, L. Mamatas, "Monitoring Virtual Networks", 12th IEEE/IFIP Network Operations and Management Symposium (NOMS 2010) - International on Management of the Future Internet (ManFI 2010), 19-23 April 2010, Osaka http://www.man.org/2010/

13.  S. Clayman, A. Galis, L. Mamatas -"Monitoring Virtual Networks with Lattice"- NOMS2010/ ManFI 2010- Management of Future Internet 2010, 19-23 April 2010 Osaka, Japan http://www.manfi.org/2010/

14.  Wint Poe, F. Tusa, I. Vaishnavi, J. Melian, A. Ramos. System Architecture of Intelligent Monitoring in Multi-Domain Orchestration. EuCNC 2017, 12-15 June 2017, Oulu, Finland, http://www.eucnc.eu.

4. Information Systems facilities

This section describes a Virtual Infrastructure Information Service (VIS) processes information. 5G infrastructures will require Information Exchange Management as a Service in order to operate correctly within one domain, as well as addressing some multi-domain aspects. Such a service will address the information exchange between components of the whole system, as well as matching with the further data processing required of monitoring.

We observe that both the SDN and NFV paradigms use a number of management and control components, called MCEs (Management and Control Entities), that are used for exploiting, handling, and communicating (i.e. between each other) management information. These MCEs are characterized by diverse requirements in terms of information manipulation.

Such information communication interchange and handling can be abstracted away within a logically-centralized information management infrastructure, that has been designed considering the unique characteristics of the challenging SDN / NFV paradigm and technologies. Basically, the information manipulation should have similar characteristics in terms of flexibility, adaptability, scalability, and stability as the network environment it supports.

The Virtual Infrastructure Information Service, supporting Information Exchange Management, has the following facilities:

  • information collection, information aggregation, and information dissemination.
  • information storage, information indexing, and information processing (such as initial attempts at knowledge production, where we define knowledge as the global-picture information for the network environment).
  • information flow establishment and optimisation, supporting both global and local tuning of involved performance trade-offs, for management information flows.
  • alternative communication methods between information sources and information sinks, such as the Push/Pull, Publish/Subscribe (pub/sub), and Direct Communication methods.
  • logically-centralized path optimization for the management of information flows.
  • interfaces for both information exchange and management information flows regulation.
  • accommodation of extensions, in an architecture aligned to both physical and virtual network environments, that can improve its behaviour further.

The VIS framework can be downloaded from http://clayfour.ee.ucl.ac.uk/ikms/index.html


15.  L. Mamatas, S. Clayman, and A. Galis, "A flexible information service for management of virtualized software-defined infrastructures" - International Journal of Network Management- published 15th July 2016 DOI: 10.1002/nem.1943; http://onlinelibrary.wiley.com/doi/10.1002/nem.1943/full

16.  L. Mamatas, S. Clayman, A. Galis -"Information Management as a Service for Network Function Virtualization Environments - IEEE Transactions on Network and Service Management — (IEEE TNSM), DOI: 10.1109/TNSM.2016.2587664, Publication date: August 2016

17.  L. Mamatas, S. Clayman, M. Charalambides, A. Galis and G. Pavlou "Towards an Information Management Overlay for Emerging Networks"- 12th IEEE/IFIP Network Operations and Management Symposium (NOMS 2010), 19-23 April 2010 Osaka, Japan, www.ieee-noms-org



Profile picture of Alex Galis
Prof Alex Galis
Professorial Research Associate

Institute of Communications and Connected Systems
Roberts Building
University College London

Profile picture of Francesco Tusa
Dr Francesco Tusa
Research Associate

Institute of Communications and Connected Systems
Roberts Building
University College London

Profile picture of Stuart Clayman
Dr Stuart Clayman
Senior Research Associate

Institute of Communications and Connected Systems
Roberts Building
University College London