A key objective of 5G and Software Defined Networking (SDN) technologies is the provision of Quality of Service (QoS) guarantees. These guarantees are reflected to the requirements emerging from the agreements between the customers and service providers, the corresponding Service Level Agreements (SLAs). While traditional SLAs included aspects for example regarding data center availability of "five 9s", or five minutes of downtime per year [1], a 5G-driven SLA includes additional aspects related both to the infrastructure and to the provisioned services, as for example: “five 9s availability” while also “2 seconds to deploy a new Service Instance”.
But what is an SLA? An SLA is a contract between the Network Service (NS) provider and the customer, which underlines each party’s responsibilities while at the same time defining the performance standards that are to be met by the provider [2]. SLAs establish customer expectations regarding the service provider's performance and overall quality. Over the past few years, SLAs set the expectations for a service provider performance, establish penalties for missing the targets and, in some cases, bonuses for exceeding them. In that concept, SDN explosion could not leave unaffected the evolution of SLA models, and their flexibility in adapting more demanded parameters. 5GTANGO is a frontrunner in defining SLAs for 5G environments, by introducing a complete SLA Management Framework, in order to fulfill the gap between NS providers and their customers [3].

Key business benefits of SLAs establishment

As all kind of business arrangements, including telecoms, have a contract, equally important is for NS providers to specify SLAs, due to the fact that constitutes a single document that contains the terms of the agreement as understood by both parties. With an SLA in place, all involved parties aim at fulfilling the terms specified in the agreement and avoid SLA violations [4]. Beyond services, SLAs can also include important security and compliance measures. In this respect, one can think of an SLA like an insurance policy for the instantiated network service.
With many telecom operators and NS providers already striving for a high level of service, what is the importance of establishing SLAs in the 5G domain? The added value is highlighted in several different contexts, such as:

  • Increased business opportunities. Service providers are being constantly compared and evaluated to competitive organizations that a customer works with. One way to stand out from all other organizations is by providing excellent customer service reinforced by a solid SLA. It is important to negotiate the agreements, to meet the customers’ exact needs, which should also be fair for the providers’ businesses. Therefore, leveraging business SLAs can be an incredibly powerful sales tool, as a “certification” of quality. Service providers should ask their customers about their experience with the agreed SLAs, while they are performing their due diligence.
  • Managing customer expectations. Without an SLA, telecoms risk customers, assuming that a NS may be 100% available, 100% of the time. By setting realistic expectations into the SLA though, the providers are covered in the event that outages or failures occur.
  • Specifying clear and measurable guidelines. An SLA is a key element to ensure customers and service providers are on the same page in terms of standards and service’s guarantees. Through the creation of an SLA, the two stakeholders can work through the desired expectations and ensure a common understanding.
  • Reflecting actual performance. Having the ability to capture monitoring data and associate them with the corresponding signed SLAs for each NS instantiation, provides the organizations with the ability to make key business decisions more efficient. These data provide valuable insight into which Network Service provider is delivering the services according to the requirements captured in the SLAs, while providing additional actionable information for the actual provided performance.

5GTANGO SLA Management

The SLA Manager is part of the 5GTANGO Service Platform, and the overall workflow is depicted in Figure 1, which consists of four discrete phases. All the interactions and management requests are based on Rest APIs and include the following: a) Definition and advertisement of the capabilities of network operators in SLA Template forms, b) Creation and management of the agreements per network service and slice, c) Monitoring the agreement compliance during runtime and d) Management of the SLA violations records. It is worth mentioning that an agreement between a network operator and a customer specifies one or more SLOs, that are expressions of the requirements of the customers and of the assurances of the service providers [5].

Introducing License-based SLAs

Apart from the well-known advantages SDN is bringing to the spectrum, software licensing is changing also, reflecting on how organizations and individuals use software. For enterprises that rely on software to maintain a market share, the software licensing model can strongly influence the return on software investment. Global, technical and economic needs affect licensing in many ways and thus creating licensing models and techniques that reflect and serve organizations’ needs, becomes increasingly challenging in the SDN/5G era. Software licensing is any procedure that lets a vendor or user, purchase, install, and use software (i.e. network services) on a machine or network in accordance with a software vendor’s licensing agreement. Software licensing aims to protect both the vendor’s investment by minimizing the risk of hard piracy and the enterprise’s investment by minimizing the risk of auditing fines from soft piracy. Utility computing puts strain on traditional licensing models. Per-user licensing is not practical in these situations and vendors may not be happy if their per-processor licenses are used to serve several customers instead of only one. In this context, SLA management enables correlation of NSs with licensing schemes. 5GTANGO proposes a service-based licensing model, which links a license to a specific customer and an instantiated NS, by specifying also the number of allowed NS instances. The model provides three types of licenses: a) trial, which supports limited time of trying the desired NS before license purchasing, b) public, which comes with no instantiation restrictions, and c) private, which specifies as mandatory the purchase of a license before instantiating a NS. It is worth mentioning that licensing is provided "as a service” and it is included into the provided SLAs [6].

Conclusion

5GTANGO provide a complete SLA management framework, being the first 5G environment that introduces SLAs in the overall lifecycle of network services. As such, it allows the establishment of SLAs that reflect formalized QoS requirements, agreed both by the provider and by the customers [8]. The key benefit for the customers is the guaranteed service quality, while service providers benefit from the flexibility and agility offered by SLAs in terms of precisely defined responsibilities and tasks, linked with QoS parameters. The latter is also reflected to predictable resource provisioning, uninterrupted end-user experience and “certification” of the provided service quality. Afterall, isn’t it what every telecom business needs nowadays?

References

[1] “IT service-level agreements and SDN: Assuring virtualization performance”, Online: https://searchnetworking.techtarget.com/tip/IT-service-level-agreements-and-SDN-Assuring-virtualization-performance
[2] M. N. Nxumalo, M. O. Adigun and I. Mba, "An Envisaged SLA-Based Cloudlet Business Model for Ensuring Service Guarantees," 2018 International Conference on Advances in Big Data, Computing and Data Communication Systems (icABCD), Durban, 2018.
[3] E. Kapassa, M. Touloupou, D. Kyriazis, “SLAs in 5G: A Complete Framework Facilitating VNF- and NS- Tailored SLAs Management”, 32nd IEEE International Conference on Advanced Information Networking and Applications Workshops (AINA), Krakow, Poland, 2018.
[4] “Service-Level Agreements 101: An Executive Guide to Service-Level Agreements (SLAs)”, Online: https://www.cio.com.au/article/268177/service-level_agreements_101_an_executive_guide_service-level_agreements_slas_/
[5] C. Parada et al., “5Gtango: A Beyond-Mano Service Platform,” in European Conference on Networks and Communications (EuCNC), 2018.
[6] 5GTANGO Consortium, “D3.2 First prototype of VNFs/NS Store”, Online: https://5gtango.eu/project-outcomes/deliverables/41-d3-2-first-prototype-of-vnfs-ns-store
[7] E. Kapassa, M. Touloupou, A. Mavrogiorgou, D. Kyriazis, “5G & SLAs: Automated proposition and management of agreements towards QoS enforcement”, 21st IEEE Conference on Innovation in Clouds, Internet and Networks (ICIN), Paris, France, 2018.

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