Cautious Weight Tuning for Link State Routing Protocols

Link state routing protocols are widely used for intradomain routing in the Internet. These protocols are simple to administer and automatically update paths between sources and destinations when the topology changes. However, finding link weights that optimize network performance for a given traffic scenario is computationally hard. The situation is even more complex when the traffic is uncertain or time-varying. We present an efficient heuristic for finding link settings that give uniformly good performance also under large changes in the traffic. The heuristic combines efficient search techniques with a novel objective function. The objective function combines network performance with a cost of deviating from desirable features of robust link weight settings. Furthermore, we discuss why link weight optimization is insensitive to errors in estimated traffic data from link load measurements. We assess performance of our method using traffic data from an operational IP backbone

Controlling the handover mechanism in wireless mobile nodes using game theory

This paper proposes a novel network selection mechanism as an extension to the FMIPv6 [2] protocol, which improves handover latency in the MIPv6 [1] in the case where the Mobile Nodes (MN) have a single wireless interface with multiple Care-of-Addresses (CoA’s). Moreover, this paper proposes a novel interface/network selection mechanism, which is an extension to the MFMIPv6 [5], which work when the mobile node has more than one wireless interface. Generally, the previous access router (PAR) in the FMIPv6 protocol forwards all the arrived packets to the new access router (NAR) by setting up a tunnel to it in order to prevent packet losses incurred by latency during handover procedure. However, there is no protocol which offers the user and/or the application to dynamically choose the right NAR (i.e. the one offers a better service). What’s more, one of the main objectives of the next generation networks will be heterogeneity in the wireless access environment in which a mobile terminal will be able to connect to multiple radio networks simultaneously. For these reasons, network selection and efficient load balancing mechanisms among different networks will be required to achieve high-speed connectivity with seamless mobility. To this end; Game Theory [3], naturally becomes a useful and powerful tool to research this kind of problems. Game theory is a mathematical tool developed to understand competitive situations in which rational decision makers interact to achieve their objectives. The mechanism improves the handover latency, the user ability to choose the right interface/network and controls when to force the MN to make the handover

PACKER: a switchbox router based on conflict elimination by local transformations

PACKER is an algorithm for switchbox routing, based on a novel approach. In an initial phase, the connectivity of each net is established without taking the other nets into account. In general, this gives rise to conflicts (short circuits). In the second stage, the conflicts are removed iteratively using connectivity-preserving local transformations. They reshape a net by displacing one of its segments without disconnecting it from the net. The transformations are applied in a asystematic way using a scan line technique. The results obtained by PACKER are very positive: it solves all well-known benchmark example

Router-level community structure of the Internet Autonomous Systems

The Internet is composed of routing devices connected between them and organized into independent administrative entities: the Autonomous Systems. The existence of different types of Autonomous Systems (like large connectivity providers, Internet Service Providers or universities) together with geographical and economical constraints, turns the Internet into a complex modular and hierarchical network. This organization is reflected in many properties of the Internet topology, like its high degree of clustering and its robustness. In this work, we study the modular structure of the Internet router-level graph in order to assess to what extent the Autonomous Systems satisfy some of the known notions of community structure. We show that the modular structure of the Internet is much richer than what can be captured by the current community detection methods, which are severely affected by resolution limits and by the heterogeneity of the Autonomous Systems. Here we overcome this issue by using a multiresolution detection algorithm combined with a small sample of nodes. We also discuss recent work on community structure in the light of our results

Optimized Design of Survivable MPLS over Optical Transport Networks. Optical Switching and Networking

In this paper we study different options for the survivability implementation in MPLS over Optical Transport Networks in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the traffic granularity on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. For the multilayer survivability we demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with actual technology pricing and were obtained for networks targeted to a nationwide coverage

T-WAS and T-XAS algorithms for fiber-loop optical buffers

In optical packet/burst switched networks fiber loops provide a viable and compact means of contention resolution. For fixed size packets it is known that a basic void-avoiding schedule (VAS) can vastly outperform a more classical pre-reservation algorithm as FCFS. For the setting of a uniform distributed packet size and a restricted buffer size we proposed two novel forward-looking algorithms, WAS and XAS, that, in specific settings, outperform VAS up to 20% in terms of packet loss. This contribution extends the usage and improves the performance of the WAS and XAS algorithms by introducing an additional threshold variable. By optimizing this threshold, the process of selectively delaying packet longer than strictly necessary can be made more or less strict and as such be fitted to each setting. By Monte Carlo simulation it is shown that the resulting T-WAS and T-XAS algorithms are most effective for those instances where the algorithms without threshold can offer no or only limited performance improvement