Photon Netw Commun DOI 10.1007/s11107-013-0415-1 Dynamic source aggregation of subwavelength connections in elastic optical networks Pouria Sayyad Khodashenas · Jaume Comellas · Salvatore Spadaro · Jordi Perelló Received: 26 February 2013 / Accepted: 27 September 2013 © Springer Science+Business Media New York 2013 Abstract Elastic optical network technologies arise as promising solutions for future high-speed optical transmis- sion, since they can provide superior flexibility and scala- bility in spectrum allocation toward the seamless support of diverse services along with the rapid growth of Inter- net traffic. In elastic optical networks, heterogeneous traf- fic demands are typically supported by a single type of bandwidth-variable transmitters, which is not always spec- trum and cost-efficient. In light of this, the aggregation of same source but different destination subwavelength con- nections has been recently introduced for elastic optical net- works, aiming to obtain both transmitter and spectrum usage savings. In this paper, we propose a novel algorithm for dynamic source aggregation of connections. Moreover, we introduce a novel node architecture enabling the realization of the proposed source aggregation in a cost-effective way. The obtained results demonstrate considerable improvement in the network spectrum utilization, as well as a significant reduction in the number of necessary transmitters per node. Keywords Elastic optical network · Source aggregation · Network optimization 1 Introduction Triggered by emerging services such as high-definition video distribution or social networking, the IP traffic volume has been exponentially increasing to date. Furthermore, the traf- fic growth rate will not stop here due to the day-by-day tech- P. Sayyad Khodashenas (B ) · J. Comellas · S. Spadaro · J. Perelló Advanced Broadband Communications Center (CCABA), Universitat Politècnica de Catalunya (UPC), Jordi Girona 1-3, 08034 Barcelona, Spain e-mail: pkhodashenas@tsc.upc.edu nology advances. For example, new hardware advances such as multicore processing, virtualization, and network stor- age will support new-generation e-Science and grid appli- cations, requesting data flows of 10 Gb/s up to terabit level. The predictable consequence in the near future is that the network operators will require a new generation of optical transport networks to serve this huge and heterogeneous vol- ume of traffic in a cost-effective and scalable manner [1, 2]. In response to this large capacity and diverse traffic gran- ularity need of future Internet, the elastic optical network architecture was proposed (e.g., see [3]). By breaking the fixed-grid spectrum allocation limit of conventional wave- length division multiplexing (WDM) networks, such elas- tic optical networks increase the flexibility of the lightpath provisioning. To do so, depending on the traffic volume, an appropriate-sized optical spectrum is allocated to a connec- tion in elastic optical networks, that is, unlike the rigid optical channels of conventional WDM networks, an elastic optical path can expand or contract elastically to meet different traf- fic loads [4]. In this way, incoming traffic demands can be served in a spectrum-efficient manner. As shown in Fig. 1a, current WDM networks allocate a full wavelength capacity to a lightpath, even if the supported traffic demand is not sufficient to fill the entire wavelength capacity (subwave- length connections). This operation leads to inefficient uti- lization of network spectral resources. Moreover, for traffic demands greater than a wavelength capacity, multiple inde- pendent WDM channels are traditionally allocated (super- wavelength connections). Note, as well, that spectral guard bands are necessary between adjacent channels for switch- ing purposes, which further increases the spectrum overhead. To provide better spectrum utilization, as shown in Fig. 1b, elastic optical networks tightly tailor the allocated spectrum to the specific demand requirements, regardless of the total (sub- or super-wavelength) bandwidth they require. 123