SIMUTools2010

The role of the simulation for a network operator: a survey

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Antonio Elizondo - Telefónica I+D, Spain

Abstract: Simulation plays an important role for designing, planning and operating a telecommunication network while assuring the quality of service since they allow one to:

• evaluate different design alternatives, ensuring the choice of the most appropriate option.
• identify and avoid potential system bottlenecks.
• evaluate the performance, capacity and scalability of networks and systems.
• elaborate dimensioning and planning rules in function of the foreseen traffic.

Telecommunications are in a constant and continuous process of transformation due to the proposal, introduction and evolution of new technologies. These technologies are more and more complex, and simulations are frequently the only means for evaluating and analyzing them before they are available to be tested.

In this talk, I will make a survey of the applications of the simulations made by a network operator such as Telefónica as a support of the network evolution. We will start with the application of simulations in legacy circuit switched networks, passing through ATM networks, and arriving to IP networks and future LTE technology. I will describe the simulations of these technologies covering topics such as traffic control (network management, admission controls, TCP protocol), routing strategies and mechanisms, P2P networks, radio access technologies, OSS and BSS systems, and service platforms.

Full presentation

Hierarchical Routing With QoS

More about Wai Sum Lai...

Wai Sum Lai - AT&T Labs

Abstract: We present our use of simulation in the analysis and design of hierarchical routing systems with support for quality of service (QoS). Hierarchical routing is used in most large networks for routing to scale in size. By using topology aggregation, a multi-level hierarchy of sibling and child clusters can be obtained. Without revealing its internal structure, a cluster in a hierarchical system can advertise to other clusters its entry-to-exit transit QoS characteristics, such as delay and available bandwidth. These QoS characteristics can be expressed in terms of the parameters of some paths between each of the cluster’s border-node pairs. When there are multiple QoS characteristics, it is generally not possible to pick a single path that simultaneously optimizes all of the parameters. Given a node pair, a minimum-weight path (in terms of either delay and/or hop count) has the smallest weight among all the paths but not necessarily the most available bandwidth. A widest path has the most available bandwidth, but usually has more delay or hops than a minimum-weight path. As a result, neither of these paths reflects accurately what is actually available inside a cluster to meet user QoS requirements, potentially resulting in sub-optimal routing.

Based on our operational experience and through simulation analysis, we discuss the pros and cons of using these paths by a cluster to advertise its transit QoS characteristics. Moreover, we show that advertising widest paths may interfere with normal operational procedures in the addition or deletion of links. As a practical solution, we propose the use of constrained minimum-weight paths for advertisement, to balance the need for smaller weights and sufficient available bandwidth.