Parc Bandwidth on Demand
by Helmut Simonis
Running demanding services like video conferencing over the Internet is not easy, with packet loss and jitter making it a less than enjoyable experience. The Parc Bandwidth on Demand (BoD) system helps Internet service providers to sell and differentiate high-quality, short-term connectivity for video conferences and other services, thereby avoiding these problems.
The system allows customers to request large amounts of bandwidth for short periods of time, with a firm guarantee of high quality of service (QoS). Requests are processed automatically and, if accepted, are provisioned automatically. The system ensures that requests are only accepted if all QoS guarantees can be met.
A typical example would be a two-hour video conference starting at some fixed time, which requires a reliable (low packet-loss), low latency connection between a number of locations around the world. A requirement might be imposed that the accepted demands must not cause the service level agreements (SLAs) of any existing customer to break. To meet this requirement it is necessary to account for the bandwidth use in the network. The system does this with an automated workflow.
The customer books the BoD service on-line via a portal up to 24 hours in advance. If the request can be accepted he receives an email confirmation within two hours. At the requested start time, a traffic-engineered (MPLS-TE) tunnel is set up between the service end-points and the access control bandwidth limits are modified. When the service is over, the tunnel is automatically removed and access control limits are reinstated for the customer. All these operations are performed automatically without human intervention: the customer is 'self-provisioning' the request on the network.
At all times, the BoD system controls the available bandwidth and rejects user demands that exceed the available capacity for the requested time period. In this way QoS is guaranteed for all services at all times.
The system uses different hybrid solvers:
- the Route Generator module finds routes in the network which satisfy delay and capacity limits
- the Commitment Solver compares the committed bandwidth in the network with current and historical traffic measurements and determines the available capacity for additional services.
These solvers are implemented in ECLiPSe, our constraint-programming environment, and use a combination of constraint, local search and mathematical programming techniques. The hybridisation allows us to find near-optimal solutions in a limited time, and to scale the algorithms even for large networks.
The system was developed jointly by Parc Technologies and IC-Parc, Imperial College London for an industrial partner, and has been implemented on a global MPLS network. Parc Technologies is a start-up company developing decision-support systems for network problems. IC Parc is a research department in the faculty of Engineering, Imperial College London. The Parc Bandwidth on Demand Solution is only one of several constraint-based systems that have been developed by Parc Technologies in the networking area in recent years.
Helmut Simonis, Parc Technologies Ltd, UK
Tel: +44 (0) 207 594 8463