Web graphs are approximate snapshots of the web, created by search engines. They are essential to monitor the evolution of the web and to compute global properties like PageRank values of web pages. Their continuous monitoring requires a notion of graph similarity to help measure the amount and significance of changes in the evolving web. As a result, these measurements provide means to validate how well search engines acquire content from the web. In this paper we propose five similarity schemes: three of them we adapted from existing graph similarity measures, and two we adapted from well-known document and vector similarity methods (namely, the shingling method and random projection based method). We empirically evaluate and compare all five schemes using a sequence of web graphs from Yahoo!, and study if the schemes can identify anomalies that may occur due to hardware or other problems.

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Abstract-The ever-increasing need to diversify the Internet has recently revived the interest in network virtualization. Network virtualization carries a significant benefit to Service Providers, as it enables the deployment of network services within customized virtual networks (VN) that offer performance and reliability guarantees. VN embedding across multiple substrate providers creates the need for a layer of indirection which is fulfilled by VN Providers. VN Providers are expected to have very limited knowledge of the physical infrastructure, since substrate providers do not disclose their network topology and resource information. This entails significant implications on resource discovery and assignment.In this paper, we study the challenging problem of multidomain VN embedding with limited information disclosure (LID). In this context, we discuss the visibility of VN Providers on substrate network resources and question the suitability of topologies for VN request specifications. Our main contributions are as follows: (i) we present a traffic matrix based VN embedding framework that enables VN request partitioning under LID, and (ii) we conduct a feasibility study on VN embedding with LID compared to a "best-case" scenario where all information is available to VN Providers.

In the future, virtual networks will be allocated, maintained and managed much like clouds offering flexibility, extensibility and elasticity with resources acquired for a limited time and even on a lease basis. Adaptive provisioning is required to maintain virtual network topologies, comply with established contracts, expand initial allocations on demand, release resources no longer useful, optimise resource utilisation and respond to anomalies, faults and evolving demands.In this paper, we elaborate on adaptive virtual resource provisioning to maintain virtual networks, allocated initially on demand, in response to a virtual network creation request. We propose a distributed fault-tolerant embedding algorithm, which relies on substrate node agents to cope with failures and severe performance degradation. This algorithm coupled with dynamic resource binding is integrated and evaluated within a medium-scale experimental infrastructure.

The Internet has seen a proliferation of specialized middlebox devices that carry out crucial network functionality such as load balancing, packet inspection and intrusion detection. Recent advances in CPU power, memory, buses and network connectivity have turned commodity PC hardware into a powerful network platform. Furthermore, commodity switch technologies have recently emerged offering the possibility to control the switching of flows in a fine-grained manner. Exploiting these new technologies, we present a new class of network architectures which enables flow processing and forwarding at unprecedented flexibility and low cost.