Semantic networking. More intel, better networks?

Today's communication networks are designed to carry traffic characteristic of a wide variety of services. Each of these services has its own connectivity requirements, which are just as varied: they can be expressed in terms of transit time, latency, robustness, security, reliability, availability and so on.

These requirements can be specified in a Service Level Agreement (SLA) between the service provider and the service customer, or between a service provider and a connectivity provider. The content of SLA clauses is (in principle) taken into account during the service design, production and operation phases. The corresponding traffic routing policies are then adjusted so that they can accommodate the requirements of connectivity services, and in particular take into account the traffic profiles characteristic of the services deployed.

However, conventional network functions such as "hop-by-hop" routing of IP packets along paths established according to the results of a dynamic route calculation that only takes into account the administrative cost associated with each of the router interfaces involved may prove limited: this is the case, for example, with wireless sensor networks, where conventional network functions are unable to take into account the state of charge of each sensor's battery. This inability can lead to sub-optimal traffic routing policies.

Thus, the richness and complexity of certain services are likely to motivate research and development of more sophisticated network functions. Their ability to take into account information other than the destination address recorded in a packet header when making a routing decision should facilitate the implementation of differentiated traffic routing policies within a network. Of course, these functions must be adjustable so that routing decisions made locally by network equipment are consistent throughout the same network.

This article describes the concept of semantic networks, i.e. networks equipped with routing and routing functions capable of taking into account information characteristic of a connectivity service, a traffic profile, the energy consumed by network elements, or even their carbon footprint. In contrast to conventional practices, in which applications associate a specific meaning with certain bits of a packet, semantic routing aims to harmonize these different approaches and provide a common framework for conveying information that will condition the services offered when a packet is transferred in a network.