On the use of flow migration for handling short-term overloads

In this work, we investigate flow migration as a mechanism to sustain QoS to network users during short-term overloads in the context of an MPLS IP network. We experiment with three different control techniques: static long-term optimal mapping of flows to LSPs; on-line locally optimal mapping of flows to LSPs at flow set-up time; and dynamic flow migration in response to transient congestion. These techniques are applicable over different timescales, have different run-time overheads, and require different levels of monitoring and control software inside the network. We present results both from detailed simulations and a complete implementation using software IP routers. We use voice-over-IP as our test application, and show that if end-to-end quality is to be maintained during short unpredictable bursts of high load, then a fast-timescale control such as migration is required.