Presenter

Halabi Wajdi - ETRO-VUB

Abstract

Most of the service applications converge over the Internet Protocol (IP) and the amount of internet traffic is growing continuously. This has triggered the advent of IP based optical networks for which the data rate of a channel, being a wavelength, goes from 10 to 100Gbit/s with more than 100 channels offered on a single fiber.
Accommodating a connection request on an IP over an optical network can be done by finding and creating a new lightpath in the optical layer, but also by adding traffic to already existing lightpaths, an action which is called grooming. Grooming allows to combine a number of low-speed traffic streams from users so that the high capacity offered by each lightpath can be used as efficiently as possible. A new connection can be accommodated by asking additional resources from the optical (the physical) plane or by adding traffic to already established lightpaths on the IP plane (the virtual plane). The problem of routing, traffic grooming and supporting service differentiation (DiffServ) to provide an appropriate Class of Services (CoS) while providing efficient resource usage have been well investigated in IP-based optical single domain networks, but not yet in multi-domain IP-based optical networks.

This thesis addresses routing, traffic grooming and DiffServ in multi-domain IP-based optical networks. Security, business and scalability reasons, refrain domain operators from sharing their domain internal information with other domain operators. For example, they will not spread detailed information about the state of the physical and virtual network outside their own domain. This is not only to avoid heavy control traffic load, but also not to expose the internal state of their network to competitors. To cope with these limitations, topology abstraction techniques and hierarchical routing will be deployed. Both techniques have been well-studied for packet-switching IP and/or cell-switching asynchronous transfer mode (ATM) networks, but not yet in IP based optical multi-domain networks.

In this work we propose a new routing methodology for service provisioning in optical multi-domain multilayer networks. Our proposed methodology adapts a two layer hierarchical routing model, which uses a Full Mesh (FM) virtual topology abstraction algorithm and also proposes an associated inter-domain routing and signaling scheme. Routing and path computation implements the core of the multi-domain grooming function therefore we considered in our proposed routing methodology the aspect of traffic grooming for efficient usage of lightpath capacity in the multi-domain scenario.

The convergence of most Internet services on the IP layer, has brought the need to provide transport for a variety of service applications, which have different Quality of Service (QoS) requirements. Here we argue that service differentiation can be achieved by using a different routing policy for each Class of Service (CoS). Based on the decoupling of the physical topology from the dynamically created IP topology, called Virtual Topology, there are two routing policies known in IP-based optical networks, the first one is Physical Topology First (PTF) and the second is Virtual Topology First (VTF), which differ in the order of actions to take in order to accommodate a new connection request. PTF will first try to set up a new lighpath in the optical plane while VTF will first try to groom the traffic imposed by the new connection on the virtual plane. Proposing the DiffServ paradigm in IP-based multi-domain networks requires the development of a routing approach, which supports both multilayer routing policies VTF and PTF in a multi-domain scenario. We propose a new cross layer routing approach, which can accommodate new service requests using both VTF and PTF. Then we use this cross layer routing approach to apply and evaluate three service differentiation schemes.