Network Service – a capability that facilitates a network operation. It typically is provided by a server (which can be running one or more services), based on network protocols running at the application layer in the Open Systems Interconnection (OSI) model of the network. Some examples are domain name system (DNS), dynamic host configuration protocol (DHCP), voice over internet protocol (VoIP), etc.

ETSI Industry Specification Group (ISG) in the Network Functions Virtualisation (NFV); Terminology for Main Concepts in NFV, a network service is a composition of network functions and defined by its functional and behavioural specification.

NOTE: The network service contributes to the behaviour of the higher layer service, which is characterised by at least performance, dependability, and security specifications. The end-to-end network service behaviour is the result of the combination of the individual network function behaviours as well as the behaviours of the network infrastructure composition mechanism.

What are the types of network services?

Types of Networking Services

• Network (WAN) Optimisation. Latency and bandwidth constraints often cause enterprise WANs to suffer from performance issues. …
• Interconnection. …
• Software Defined WAN (SD-WAN) …
• Multi-Protocol Label Switching (MPLS) …
• Ethernet Private Line Network.