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Appendix 8. Circuit Oriented Networks

Submitted by Artur Barczyk(Artur.Barczyk@cern.ch)

February 2008

Introduction:

Since 2002, circuit-oriented networks and services (COS) have been identified, in the DOE High

Performance Network Planning Workshop 0 and other studies (e.g. 0, 0), as one of the most

important new directions for networks supporting data intensive science.

The identified uses and/or benefits of virtual circuits include:

1.

Guaranteed bandwidth, and (with advanced data transfer tools) predictable high

throughput.

2.

Traffic isolation and traffic engineering. This permits the use of transport mechanisms

(e.g., protocols specialized for long-haul, high-speed bulk data transfers) that cannot

easily co-exist with best-effort TCP-based transport protocols used in the IP network.

3.

Secure end-to-end connections between lab and collaborator systems. VC setups involve

secure authentication and authorization processes, and the network routing policy

enforced in the routers excludes other traffic sources from using the circuit.

4.

Guarantees for time critical traffic, e.g., for detector calibration at remote computing

sites, or real-time control of an instrument based on output of the instrument, as in the

case for remote control rooms for the LHC.

The use of virtual circuits in parallel with a traditional network service supporting a general

traffic has thus several advantages. High priority flows can be delivered in time to meet

deadlines, and the many smaller flows in the general traffic mix can be isolated and thus

protected from the impact of large flows whose characteristics are optimized for high throughput,

and vice versa.

In the case of the LHC there is the additional issue that network bandwidth will have to be

carefully managed to meet many diverse demands from the experiments. In such an environment,

and indeed in any scenario where bandwidth is limited and thus should be used efficiently, one

has to schedule the flows, and this leads to a need for dynamic connection provisioning.

The provisioning of dynamic circuits has become the mainstream direction adopted by the major

mission oriented and Research and Education networks, such as ESnet, Internet2, GEANT2,

USLHCNet and the leading NRENs.

Internet2 Dynamic Circuit Network:

The Internet2 DCN 0 is a switching service that creates short-term circuits between end-users that

require dedicated bandwidth, including reliable connections lasting from minutes to days. It

enables users to create point-to-point circuits across the Internet2 infrastructure, using control

plane software that automates the set up and tear down of the circuits.

The Internet2 DCN currently uses an experimental open source version of the DRAGON-

developed control plane software 0 as well as internationally developed inter-domain

communications schemas, allowing circuits to be created seamlessly and directly by the

applications themselves.

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