Context to NSI In recent years adoption of control plane protocols such as GMPLS have allowed network operators to support fast automated creation of connection-oriented circuits within their networks. As these services are rolled out in research and education networks to support the demanding connectivity requirements of projects such as grids, demand for inter-operator co-ordination of these services is increasing. Existing protocols such as GMPLS are inherently single layer in nature and do not readily interoperate between networks of heterogeneous technology. The Network Service Interface (NSI) standard defines an interface that will allow an arbiter such as grid middleware to request a connection oriented service that spans multiple networks. This network service setup requires configuration, monitoring and orchestration of network resources across each network under particular agreements and policies. The Network Service Interface assumes the existence of a Network Service Agent (NSA) which is capable of controlling a set of network resources - for transmission equipment this could typically be a network management system operating in accordance with TMN principles. The NSA is able to authorize, reserve, schedule, instantiate, monitor, teardown, negotiate, and log its resources and the connections which are created from the resources. The Network Service Interface is then defined as being the interface between a Requestor Agent (for example grid middleware) and the NSA. To support reservation of resources across multiple operators, the NSI interface must support the following messaging services: * Topology exchange service * Path computation service * Signalling service * Authorization and Authentication service While the NSI definition does not mandate any standards for implementation of these services within a network operator domain, a standardised exchange of information over the NSI interface is required. So for example domain internal path computation may be performed by the operators preferred method (such as PCE), however the results of this computation should be exchanged is standardised in NSI. The NSI interface is intended to be implemented either: 1. Between an application layer (for example grid middleware) to operator service plane layer. 2. Between operator service plane layers. ------------------------------------------------------------------------------------------------------------------ Guy Roberts, Ph.D Network Engineering & Planning DANTE - www.dante.net<http://www.dante.net/> Tel: +44 (0)1223 371 316 City House, 126-130 Hills Road Cambridge, CB2 1PQ, UK ------------------------------------------------------------------------------------------------------------------