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Research Directions in Network Service Chaining
Wolfgang John, Kostas Pentikousis, George Agapiou, Eduardo Jacob, Mario Kind, Antonio Manzalini, Fulvio Risso, Dimitri Staessens, Rebecca Steinert, Catalin Meirosu
TL;DR
Carrier networks need more flexible and efficient service deployment, but NSC remains insufficiently defined and its enabling technologies and research challenges remain open. The paper defines dynamic, carrier-grade NSC, presents design considerations and use cases, and organizes research directions across the service lifecycle. It concludes that dynamic NSC could improve flexibility, time-to-market, and carrier CAPEX/OPEX while introducing substantial challenges in scalable delivery, testing, observability, and debugging.
Problem
Carrier networks face rigid, costly service infrastructures, while NSC lacks a settled peer-reviewed definition and clear agreement on enabling technologies and research challenges.
Method
The paper defines dynamic carrier-grade NSC, develops design considerations and use cases, and surveys research challenges across description, programming, deployment, delivery, security, and debugging.
Results
The paper identifies dynamic NSC as a basis for more flexible service deployment, traffic steering, and potential carrier CAPEX/OPEX and time-to-market reductions.
Takeaways & Limitations
Dynamic NSC could reshape how carrier networks design, operate, and maintain services, provided its lifecycle, scalability, testing, observability, and fault-isolation challenges are addressed.
Abstract
from arXiv · showhide
Network Service Chaining (NSC) is a service deployment concept that promises increased flexibility and cost efficiency for future carrier networks. NSC has received considerable attention in the standardization and research communities lately. However, NSC is largely undefined in the peer-reviewed literature. In fact, a literature review reveals that the role of NSC enabling technologies is up for discussion, and so are the key research challenges lying ahead. This paper addresses these topics by motivating our research interest towards advanced dynamic NSC and detailing the main aspects to be considered in the context of carrier-grade telecommunication networks. We present design considerations and system requirements alongside use cases that illustrate the advantages of adopting NSC. We detail prominent research challenges during the typical lifecycle of a network service chain in an operational telecommunications network, including service chain description, programming, deployment, and debugging, and summarize our security considerations. We conclude this paper with an outlook on future work in this area.
I. INTRODUCTION
Traditional carrier networks rely on rigid, statically assembled services while market and technology changes demand greater flexibility. The paper addresses this gap by examining dynamic NSC in carrier-grade infrastructure networks.
- I. INTRODUCTION: Operators face rising infrastructure CAPEX and OPEX as they incorporate new technologies while keeping older investments operational.
- I. INTRODUCTION: Traditional networks assemble service chains from statically configured monolithic components chosen at design time.Once deployed, operators mainly make minor configuration changes or add infrastructure for scalability.
- I. INTRODUCTION: Fixed-location monolithic platforms make advanced services such as IDS/IPS, firewalls, content filtering, DPI, and caching rigid and static.
- I. INTRODUCTION: Recent research and standardization efforts seek service-chain models that support advanced services, infrastructure efficiency, and operational efficiency.The paper notes emerging definitions of service chains and traffic steering at subscriber and traffic-type granularity.
- I. INTRODUCTION: The paper surveys NSC research directions across service-chain description, programming, deployment, and debugging for carrier-grade networks.
II. MOTIVATION
Network complexity and ossification make introducing new functionality difficult and expensive. Middlebox-heavy deployments also impose static provisioning and substantial CAPEX/OPEX burdens, motivating automation, virtualization, and service-chain research.
- II. MOTIVATION: Introducing new functionality into deployed networks is complicated, time-consuming, and expensive because existing platforms require careful engineering and customization.The paper identifies shortening the operator innovation cycle and reducing time-to-market as critical.
- II. MOTIVATION: Complexity increases as wholesale, cellular, cable, and access/aggregation operators seek access to one another’s network platforms and services.
- II. MOTIVATION: Higher automation in management and configuration could reduce OPEX through fewer touch-points and CAPEX through delayed or optimized resource investments.
- II. MOTIVATION: Carrier services such as IPTV, security, and content delivery increasingly depend on multiple independently deployed functions, including NAT, policing, firewalls, CDNs, and transcoding.
- II. MOTIVATION: Middleboxes force operators to define statically provisioned chains, while specialized closed hardware contributes to network ossification and significant CAPEX/OPEX.
- II. MOTIVATION: Early SDN-based service-chain work demonstrated modular in-network functions but did not address carrier-grade networks.
III. NETWORK SERVICE CHAINING
Dynamic NSC treats service delivery as an orchestrated association of network functions across physical and virtual infrastructure. Its benefits include configurable traffic steering and predictable cross-domain flows, but large-scale dynamic delivery creates operational challenges.
- III. NETWORK SERVICE CHAINING: Dynamic NSC is defined as a carrier-grade process for continuous service delivery based on network-function associations.Continuous delivery combines dynamic orchestration and automated redeployment; carrier-grade operation requires high availability, fast failure recovery, and integrated testing.
- III. NETWORK SERVICE CHAINING: Unlike predefined processing sequences, dynamic NSC allows traffic to traverse software-configurable and upgradeable physical or virtual service functions.
- III. NETWORK SERVICE CHAINING: Dynamic NSC can steer traffic across network domains through service functions embedded at different locations and implemented in software or hardware.
- III. NETWORK SERVICE CHAINING: Intelligent traffic steering can accelerate traffic performance and make sensitive data and multimedia flows more reliable and predictable across networks.
- III. NETWORK SERVICE CHAINING: Dynamic chains may add or remove components at runtime, requiring operators to manage many customized services and instances while preserving carrier-grade quality of experience.
IV. NSC RESEARCH DIRECTIONS
The paper organizes NSC research challenges around the lifecycle of a compound service, from its description and programming through deployment, continuous delivery, and security.
- IV. NSC RESEARCH DIRECTIONS: The research agenda follows the NSC lifecycle: service description and programming, service-instance deployment, continuous network service delivery, and security.
A. NSC Description and Programming
Dynamic NSC requires descriptions, programming models, deployment architectures, and resource mappings that support fine-grained, scalable service composition across heterogeneous carrier infrastructure.
- Programming: Dynamic chains require programming languages that express complex packet-processing policies beyond simple flow-table manipulation across physical and virtual infrastructures.
- Service description: Service and resource descriptions must support automated deployment and optimization while covering QoS, resource sharing, mobility, security, and energy-efficiency constraints.
- Resource sharing: Virtualization enables transparent resource sharing among service-chain instances, but dynamic reconfiguration creates substantial scalability requirements.
- Monitoring: Live operations require service definitions that facilitate monitoring and troubleshooting of chain instances.
- Service instance deployment: A universal-node paradigm could make the path from network edge to datacenter a homogeneous programmable platform for deploying and distributing function components.
- Service instance deployment: Future device architectures remain open, including aggregated virtual devices, heterogeneous integrated resources, and other approaches to distributed service execution.
- Modular design: Network functions raise a modularity question spanning monolithic placement to highly granular components distributed across programmable paths.
- Resource mapping: Mapping chain components to resources remains open because optimal placement under CPU, memory, interface, and location constraints is NP-hard.Probabilistic methods are identified as promising for handling network uncertainty and variation.
C. Continuous Network Service Delivery
Continuous delivery of dynamic service chains requires DevOps-like operational tooling, pre-activation model checking, programmable observation, and scalable state approximation. These capabilities must support testing and troubleshooting while balancing visibility, security, confidentiality, resource use, and signaling overhead.
- Operational tooling: Dynamic service chains require a toolbox for daily operations and troubleshooting because extensive field trials are no longer affordable.The toolbox is envisioned in a manner similar to DevOps tools used in IT operations.
- Operational tooling: Workflow definition for testing, validation, and troubleshooting remains a challenge because SDN troubleshooting workflows are complex and time-consuming.Dynamic service chains need comparable workflow support.
- Testing and validation: Model checking must occur before service activation, but static checking methods are unsuitable for dynamically changing chains.The paper points to software-development model-checking techniques as a relevant basis while identifying additional challenges for dynamic chains.
- Observability: Programmable observation points embedded during service definition can monitor network and service components and help identify problematic chain elements.Observation constructs can be assembled programmatically into tailored diagnostic tools.
- Observability: Monitoring data must be summarized and mapped to troubleshooting workflows so operators can decide on subsequent actions.The infrastructure is intended to present information in a form that supports human decisions.
- Observability: Scalable observability requires approximating network state rather than continuously reflecting exact information at very fine granularity in highly dynamic large-scale systems.This approximation addresses the potentially huge monitoring volumes produced by wide-scale programmable observation.
D. Security Considerations
NSC creates security challenges because service chaining may cross user and provider domains and because dynamic deployment changes the security assumptions of static proprietary services. Short-lived, targeted, and mobile services further motivate careful deployment design and protection of data and control-plane management.
- Cross-domain security: A service-chaining process in the provider domain may be triggered by an end user located in another domain, creating cross-domain security concerns.Existing access authentication and subsequent service authorization are part of this context.
- Dynamic services: Short-lived services for temporary performance upgrades, selected household users, or user-service mobility are difficult to support securely.The examples include premium delay for gaming, single-subscriber-network targeting, and using a subscription while visiting friends.
- Deployment security: Dynamic NSC requires new deployment-design efforts because static proprietary equipment previously provided security benefits.Virtualization can help control the scope in which services are deployed, while data- and control-plane management also has security implications.
V. FUTURE WORK
UNIFY is presented as a future-work project addressing NSC challenges through a holistic unified cloud-and-carrier-network approach. Its planned work emphasizes decomposing network functions, defining service abstractions, and enabling more flexible service creation.
- Future-work direction: UNIFY aims to provide flexible service creation for unified cloud and carrier networks, with particular focus on network functions.The project responds to carrier networks described as slow and rigid in their functions and resources.
- Future-work direction: UNIFY will study decomposing traditional fixed-mobile network functions into finer-grained components and identify the minimal component set needed for flexible chaining.This decomposition is one of four planned aspects of the unified production environment.
- Future-work direction: UNIFY will define a service abstraction model and a service-creation approach as part of its unified production environment.The passage presents abstraction and creation mechanisms alongside function decomposition as core project activities.
VI. CONCLUSION
The paper identifies dynamic NSC as a research direction for more flexible and efficient carrier networks, with challenges spanning service deployment, definition, programming, and operations. It highlights debugging, interoperability, and standardization as important future concerns.
- VI. CONCLUSION: Dynamic NSC could reduce carrier CAPEX and OPEX while increasing flexibility and accelerating time to market for network services.The paper connects these benefits to future operator networks and novel service offerings.
- VI. CONCLUSION: The paper’s research directions cover service instance deployment, network service definition, programming, operations, and continuous network service delivery.These directions address multiple stages of the network service lifecycle.
- VI. CONCLUSION: Dynamic NSC introduces unfamiliar telecommunications challenges, particularly for service-chain debugging and network fault isolation.The paper states that debugging and fault isolation entail different aspects in an NSC era.
- VI. CONCLUSION: As NSC matures, research may shift toward interoperable solutions with global reach and applicability across operator networks.The paper links this anticipated shift to international standardization.