José Luis Izquierdo Zaragoza - Research

My first steps into the research world were focused on medical image processing. Specifically, I was developing algorithms for automatic measurement of the carotid artery walls, which would help specialists to determine risks of suffering serious cardiovascular diseases. Although some interesting results were obtained (see Papers section for related works), eventually I moved to the networking field.

Optical Communications Networks

Optical multilayer IP over WDM networks are an enabling technology for building the core and metro high-capacity networks in the Next Generation Internet. In IP over WDM networks, the IP routers are connected by transparent all-optical channels, called lightpaths. A lightpath occupies a wavelength in the traversed fibers, and is optically switched at intermediate nodes. For the IP layer, the set of established lightpaths comprises a so-called Virtual Topology (VT), and packet switched IP traffic is directly routed over the VT. Thus, each lightpath corresponds to a virtual link between two routers: independently on the actual sequence of fibers traversed by the lightpath, the IP layer sees it as a pipe to transmit packets, with typical rates of 10, 40, or 100 Gbps.

Multilayer IP over WDM Networks 

The success of multilayer networks is built on their ability to efficiently combine the electronic packet switching for a finer traffic granularity, and the optical circuit switching for a coarse granularity. These two modes of switching are conducted by separated equipment in the network. The IP/MPLS routers perform a per-packet processing, buffering and switching of the IP packets, while ROADMs (Reconfigurable Optical Add-Drop Multiplexers) implement the optical add, drop and transparent bypass switching of the lightpaths. Electronic packet switches/routers are costly, bulky and power-hungry (e.g. CISCO CRS-3, 322 Tbps, 80 chassis, approx. 700 kg/chassis, consumes more than 1 MW). Their complexity originates in the need of a fast per-packet processing at very high speeds. Traffic to and from each lightpath is processed by line cards operating at wire-speed (10/40/100 Gbps), with large buffers for storing the packets. Line cards are interconnected by a switch fabric, a complex piece of hardware that permits delivery of IP packets among the line cards.

Architecture of a multilayer node 


Network planning and design is a critical process which must be performed before deploying new communication networks. Some of the basic methodologies employed in the network planning include measurement campaigns, analytical studies and computer simulations. In general, measurements are superior since they provide real data, in comparison with the analytical studies and computer simulations based on theoretical models. Conversely, analysis and simulation permit to reduce the planning costs, since expensive campaigns of measurements are not required, different network configurations can be tested in parallel or rare error simulation scenarios can be studied. To perform analytical studies and computer simulations, network planning tools must be developed. Network planners allow to simulate, analyse, dimension, optimize and evaluate the performance of the proposed network designs before of its deployment, providing us with the possibility of reaching a better understanding of existing network systems, identifying flaws or features to improve and a fast development of new systems.

The main objective of our research is to apply network planning and simulation tools to the study of optical communication networks

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