State correction after re-routing with reduced state resource reservation protocols

Abstract

Recently, a new working group - Next Steps In Signalling (NSIS) - was established within the IETF to develop a general signalling protocol primarily to support QoS resource reservation. Two main operation modes have been clarified: stateful and reduced state. The first mode relies on per flow-state information in all interior nodes while the other uses aggregated states. Stateful operation is based on the resource reservation protocol (RSVP), while reduced state operation will be similar to the resource management in a Diffserv (RMD) framework. With the use of aggregated states instead of per-flow granularity, one looses fine control over resources but derives a scalable and more efficient protocol. However, some problems need new handling mechanisms. In this paper, we discuss the problem of re-routing from the aspect of reduced state resource reservation. We show how quickly and easily RSVP handles such situations but reduced state solutions like RMD require new mechanisms for a quick reaction. We propose and analyse several solutions.