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On the Cost-Optimality Trade-off for Fast Service Function Chain Reconfiguration
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). (Disco, Distributed Systems and Communications)ORCID iD: 0000-0001-9866-8209
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). (Disco, Distributed Systems and Communications)ORCID iD: 0000-0002-9446-8143
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013). (Disco, Distributed Systems and Communications)ORCID iD: 0000-0001-9194-010X
Ericsson AB.ORCID iD: 0000-0003-2972-9252
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Optimal placement of Virtual Network Functions (VNFs) in data centers enhances the overall performance of Service Function Chains (SFCs) and decreases the operational costs for mobile network operators. In order to cope with changes in demands, VNF instances may be added or removed dynamically, resource allocations may be adjusted, and servers may be consolidated. To maintain an optimal placement of SFC under changing conditions, dynamic reconfiguration is required including the migration of VNFs and the re-routing of service flows. However, such reconfiguration may lead to notable service disruptions and can be exacerbated when reconfiguration entails state or VNF migration, both imposing additional overhead on the VNF infrastructure. On the other hand, not changing the placement may lead to a suboptimal operation, servers and links may become congested or underutilized, leading to high operational costs. In this paper, we investigate the trade-off between the reconfiguration of SFCs and the optimality of the resulting placement and service flow routing. We model reconfiguration costs related to the migration of stateful VNFs and solve a joint optimization problem that aims to minimize both the total cost of the new placement and the reconfiguration cost necessary to achieve it. We also develop a fast multi-objective genetic algorithm that finds near-optimal solutions for online decisions. Our numerical evaluations show that a small number of reconfiguration operations can significantly reduce the operational cost of the VNF infrastructure. In contrast, too much reconfiguration may not pay off due to high costs. We believe that our work is an important tool that helps network provider to plan a good reconfiguration strategy for their service chains.

Keywords [en]
Network reconfiguration, Virtual Network Function, VNF migration strategy
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:kau:diva-75904OAI: oai:DiVA.org:kau-75904DiVA, id: diva2:1377264
Funder
Knowledge FoundationAvailable from: 2019-12-11 Created: 2019-12-11 Last updated: 2020-01-14Bibliographically approved
In thesis
1. Service Migration in Virtualized Data Centers
Open this publication in new window or tab >>Service Migration in Virtualized Data Centers
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Modern virtualized Data Centers (DCs) require efficient management techniques to guarantee high quality services while reducing their economical cost. The ability to live migrate virtual instances, e.g., Virtual Machines (VMs), both inside and among DCs is a key operation for the majority of DC management tasks that brings significant flexibility into the DC infrastructure. However, live migration introduces new challenges as it ought to be fast and seamless while at the same time imposing a minimum overhead on the network. In this thesis, we study the networking problems of live service migration in modern DCs when services are deployed in virtualized environments, e.g., VMs and containers. In particular, this thesis has the following main objectives: (1) improving the live VM migration in Software-Defined Network (SDN) enabled DCs by addressing networking challenges of live VM migration, and (2) investigating the trade-off between the reconfiguration cost and optimality of the Service Function Chains (SFCs) placement after the reconfiguration has been applied when SFCs are composed of stateful Virtual Network Functions (VNFs).

To achieve the first objective, in this thesis, we use distinctive characteristics of SDN architectures such as their centralized control over the network to accelerate the network convergence time and address suboptimal routing problem. Consequently, we enhance the quality of intra- and inter-DC live migrations. Furthermore, we develop an SDN-based framework to improve the inter-DC live VM migration by automating the deployment, improving the management, enhancing the performance, and increasing the scalability of interconnections among DCs.

To accomplish the second objective, we investigate the overhead of dynamic reconfiguration of stateful VNFs. Dynamic reconfiguration of VNFs is frequently required in various circumstances, and live migration of VNFs is an integral part of this operation. By mathematically formulating the reconfiguration costs of stateful VNFs and developing a multi-objective heuristic solution, we explore the trade-off between the reconfiguration cost required to improve a given placement and the degree of optimality achieved after the reconfiguration is performed. Results show that the cost of performing the reconfiguration operations required to realize an optimal VNF placement might hamper the gain that could be achieved.

Abstract [en]

Modern virtualized Data Centers (DCs) require efficient management techniques to guarantee high quality services while reducing their economical cost. The ability to live migrate virtual instances, e.g., Virtual Machines (VMs), both inside and among DCs, is a key operation for the majority of DC management tasks that brings significant flexibility into the DC infrastructure. However, live migration introduces new challenges as it ought to be fast and seamless while at the same time imposing a minimum overhead on the network.

This thesis investigates the networking challenges of short and long-haul live VM migration in Software Defined Networking (SDN) enabled DCs. We propose solutions to make the intra- and inter-DC live VM migration more seamless. Our proposed SDN-based framework for inter-DC migration improves the management, enhances the performance, and increases the scalability of interconnections among DCs.

Moreover, by considering the overhead of VM migration over the network, servers, and quality of service the VM provides, we explore the trade-off between the costs required to change the placement of VMs and the optimality degree of the placement in the DC. Results show that the cost of improving the placement might hamper the gain that could be achieved.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2020. p. 49
Series
Karlstad University Studies, ISSN 1403-8099 ; 2020:1
Keywords
Data Center, Ethernet VPN, EVPN, Live Service Migration, Reconfiguration, SDN, Virtual Network Function, VNF
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-75921 (URN)978-91-7867-073-4 (ISBN)978-91-7867-083-3 (ISBN)
Public defence
2020-02-07, 21A342 (Eva Eriksson lecture hall), Universitetsgatan 2, 651 88, Karlstad, 10:15 (English)
Opponent
Supervisors
Funder
Knowledge Foundation
Available from: 2020-01-16 Created: 2019-12-12 Last updated: 2020-01-16Bibliographically approved

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Alizadeh Noghani, KyoomarsKassler, AndreasTaheri, Javid

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