Influence of GMPLS Recovery Mechanisms on TCP Performance

Optical networks based on wavelength-division-multiplexing (WDM) techniques are very likely to be omnipresent in future telecommunication networks. Those networks are deployed in order to face the steady growth of traffic, which is for a large part Internet related. In the resulting IP-over-WDM scenario, TCP/IP constitutes an important fraction of the traffic transported over these networks. As IP networks are becoming increasingly mission-critical, it is of the utmost importance that these networks (and hence the supporting transport networks) be able to recover quickly from failures such as cable breaks or equipment outages. To that end, several IP-over-WDM network scenarios and corresponding protection and restoration strategies have been devised. It is clear that some trade-offs will have to be made in order to choose an appropriate strategy. In this paper, we investigate the effects of such recovery actions on the behavior of TCP, being the ubiquitous protocol used by today's network users. We examine the influence of different parameters such as the speed of recovery actions, changing length of the routes followed by the client data (TCP flows), changes in available bandwidth, etc. Thereby, we focus on what the TCP end-users care about, i.e., the number of bytes transported end-to-end within a certain time interval.