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New signaling suites for a distributed control plane in wavelength division multiplexing (WDM) networks, such as generalized multiprotocol label switching (GMPLS) and automatic switched optical networks (ASON), allow one to cope with the increasing variability of traffic patterns to be supported by operators by providing a means to dynamically set up and release connections. The dissemination of link-state information [usually provided by routing protocols such as open-shortest-path-first traffic engineering (OSPF-TE)] is essential in this kind of control-plane enabled network: in particular, this information has to be continuously updated to allow routing algorithms to efficiently carry out the path computation. Most of the studies on dynamic traffic routing tend to neglect the effect of delays in control-information distribution on routing performance: in particular, even when the control plane is considered as in testbeds, emulators, or some simulations, the analysis of the effects of control plane delays is limited to a small range of values, applicable to well-specified contexts. Applying a very general control-delay representation, we are able to provide a wide-range simulative study to quantify the effect of signaling on routing performance, mainly by using the blocking probability metric. We are able to evaluate the effect of outdated information (1) for a wide interval of control delay values, (2) for a large set of routing scenarios, considering, e.g., unprotected, dedicated, and shared path protection routing, and (3) quantifying the different delay effects in the absence or in the presence of wavelength conversion capabilities.
Optical Communications and Networking, IEEE/OSA Journal of (Volume:1 , Issue: 2 )
Date of Publication: July 2009