Service Primitives (cont’d)
Services can either be confirmed or unconfirmed.
Confirmed: In a confirmed service there is a request, indication, a response and a confirm. CONNECT is always a confirmed service.
Unconfirmed: request, indication only. Data transfer (DATA) could be both confirmed or unconfirmed.
SERVICES AND PROTOCOLS: A service is a set of primitives (e.g., software operations) that a layer provides to the layer above it. How the these operations are implemented are not revealed. A protocol is a set of rules that govern the format and meaning of the frames, packets, or messages that are exchanged by the peer entities within a layer. (NOTE: service = vertical, protocol = horizontal)
Network software/Service primitives