In recent years adoption of control plane protocols have
allowed network operators to support fast automated creation of
connection-oriented circuits within their networks. These services are
being rolled out in research and education networks to support the demanding
connectivity requirements of big science projects such as grids. With
increasing international cooperation, the demand for international circuits is
also rising requiring inter-operator co-ordination of these services.
Existing providers implement a wide range of technologies
(Ethernet, SDH, OTN etc) to deliver connection oriented services. These
connections are built using a variety of control or management planes (MPLS,
GMPLS, TMN etc). Current operational practices typically require
cross-network connections to be created by each network separately and the
interconnect point to be mutually agreed by manual negotiation between
operators. This process of add-hoc manual creation has proven to be slow
and expensive and acts as an inhibitor to service uptake.
While it is possible for all providers to cooperate and
run a common control plane (such as GMPLS) the process of agreement between
providers and the timescales required to implement this common control plane is
likely to be prohibitive. For this reason, an application-to-provider network
service interface is proposed by the NSI-WG. This should be implemented
in a way that allows operators to exchange connection requests while retaining
their existing network technology and their exiting control plane.
The interface aims to be able to be rapidly deployed compared to, for example,
wide scale deployment of GMPLS eNNI. The solution should also be
readily scalable and support web service based to support network
virtualization in grid network service environments.
The Network
Service Interface (NSI) standard defines an interface that will allow a
connection oriented service that spans multiple networks to be requested.
The requestor may be either another network operator or an application such as
grid middleware. 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, in each
network, of a Network Service Agent (NSA) which is capable of controlling a set
of network resources – for transmission equipment this might 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:
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:
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Guy Roberts, Ph.D
Network Engineering &
Planning
DANTE - www.dante.net
Tel: +44 (0)1223 371 316
City House, 126-130
Hills Road
Cambridge, CB2 1PQ,
UK
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