Efficient techniques for QoS based path computation and selection in differentiated service networks

We propose techniques for incorporating QoS mechanisms into routing path computation and path selection algorithms for use in the the next generation Internet. We believe that using such techniques will help to provide a complete solution to the QoS problem. The problem of QoS routing is essentially one of finding a optimal path which will satisfy one or more constraints such as bandwidth, delay, jitter delay and minimize some cost function. This problem belongs to the class of problems known as multiobjective constrained path optimization which are known to be NP-hard. Several approximate solutions have been suggested for this problem, one of them being Orda's (see IEEE/ACM Transactions on Networking, vol.7, no.3, p.365-74, 1999). We build on some of the suggested schemes therein and apply them to a Cos network. We propose techniques which will compute a set of feasible paths which satisfy the bandwidth constraints of a path set-up request or a service level agreement (SLA). We then choose a path from amongst the feasible paths such that we have good utilization of available bandwidth and balance the load in the network. These techniques are Cos aware and adaptive, they respond to congestion in the network by routing higher classes of traffic away from congested links and nodes. The techniques are shown to be computationally tractable.