Value-added proposition of the GMPLS control plane in IP optical networks

Abstract

We quantify the value-added proposition of the generalized multiprotocol label switching (GMPLS) distributed control plane vis a vis the centralized network management (CNM) plane. Our main objective is not to propose new protocols or algorithms, but rather to provide guidance to network operators on how to maximize the benefits of deploying a GMPLS control plane. We identify two main goals for maximizing these benefits: (1) decreasing operations costs and (2) increasing revenues through enhancing the efficiency of existing network assets as well as through enabling new services. Control plane functionalities such as dynamic routing, user-initiated end-to-end connection setup, and distributed fault management in IP optical networks are analyzed to determine optimal operating regions where their values are maximized. Extensive simulations using NSFNET topology have been carried out from which we have found that there are certain operating regions where (1) the distributed routing can improve the efficiency of network assets by saving 15% of the number of wavelengths per link, or increasing traffic loads by 20%. However, if the call interarrival time is shorter than 1 min, the efficiency (in terms of call blocking ratio) of distributed dynamic routing is reduced due to the OSPF convergence delay. (2) Enabling bandwidth on demand (BoD) services at finer bandwidth granularities connections is more cost-effective to the operator than doing the same at coarse bandwidth granularities. (3) The connection setup delay is the limiting factor in determining the types of BoD services a carrier offers. The call blocking ratio will increase quickly if the average call interarrival time is less than tens of seconds. (4) Assuming only single link failure, M:N shared protection can achieve 100% recovery at the expense of 10% increase in the number of wavelengths compared with nonprotection schemes, while saving are as high as 48% wavelengths compared with 1:1 dedicated protection.