570 research outputs found

    Temporal and Spatial Classification of Active IPv6 Addresses

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    There is striking volume of World-Wide Web activity on IPv6 today. In early 2015, one large Content Distribution Network handles 50 billion IPv6 requests per day from hundreds of millions of IPv6 client addresses; billions of unique client addresses are observed per month. Address counts, however, obscure the number of hosts with IPv6 connectivity to the global Internet. There are numerous address assignment and subnetting options in use; privacy addresses and dynamic subnet pools significantly inflate the number of active IPv6 addresses. As the IPv6 address space is vast, it is infeasible to comprehensively probe every possible unicast IPv6 address. Thus, to survey the characteristics of IPv6 addressing, we perform a year-long passive measurement study, analyzing the IPv6 addresses gleaned from activity logs for all clients accessing a global CDN. The goal of our work is to develop flexible classification and measurement methods for IPv6, motivated by the fact that its addresses are not merely more numerous; they are different in kind. We introduce the notion of classifying addresses and prefixes in two ways: (1) temporally, according to their instances of activity to discern which addresses can be considered stable; (2) spatially, according to the density or sparsity of aggregates in which active addresses reside. We present measurement and classification results numerically and visually that: provide details on IPv6 address use and structure in global operation across the past year; establish the efficacy of our classification methods; and demonstrate that such classification can clarify dimensions of the Internet that otherwise appear quite blurred by current IPv6 addressing practices

    NLSR: Named Data Link State Routing Protocol

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    Named Data Networking (NDN) is a fundamental paradigm shift from the current Internet where, packets are forwarded by name instead of the destination IP address. By explicitly naming each packet and signing data, NDN enables some revolutionary features like data authenticity, multicast data delivery, and multipath forwarding with adaptive strategies. For NDN to work well over a network, it requires a routing protocol which will not only need to propagate name reachability in the network, but also compute ranked multipath forwarding entries for each name by ensuring the security of routing exchanges. Moreover, moving from a traditional, long studied, and well-understood IP based thinking process to name based routing makes designing an efficient routing protocol for NDN more challenging. This thesis presents Named-data Link State Routing (NLSR), which propagates name reachability and computes ranked multiple nexthops for forwarding. NLSR also takes advantage of inherent data authenticity features to provide simple yet robust security for routing exchanges.This thesis focuses on discussing four functional design goals of NLSR. First and foremost is designing a naming scheme for routers, routing updates, and routers\u27 cryptographic certificates. The second design goal is to make a rational choice between two available synchronization protocols for disseminating routing updates in NDN. The third goal is designing an efficient algorithm to produce multiple nexthops for each forwarding entry. The fourth and final goal is to produce a self-sufficient design for naming, distributing cryptographic certificates in the network, and deriving trust from those certificates for routing updates.The goal of this thesis is to design and evaluate a routing protocol, which will well serve the needs of NDN. NLSR moves from the conventional IP based routing to name based routing and from single path forwarding to multiple path forwarding. We have evaluated NLSR, and compared to IP link state routing protocol, it offers more efficient routing update propagation, inherent update authentication, and native support of multipath forwarding. NLSR provides a great learning experience to develop an application on top of NDN which requires meticulous consideration in namespace design, careful design of the trust model for data authentication, and most importantly, a mental adjustment to NDN\u27s design philosophy of using interest-data exchanges for routing messages. NLSR is the first distributed routing protocol in NDN for a single authoritative domain and the first step toward developing and extending protocols for inter-domain routing

    Decoupling Information and Connectivity via Information-Centric Transport

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    The power of Information-Centric Networking architectures (ICNs) lies in their abstraction for communication --- the request for named data. This abstraction was popularized by the HyperText Transfer Protocol (HTTP) as an application-layer abstraction, and was extended by ICNs to also serve as their network-layer abstraction. In recent years, network mechanisms for ICNs, such as scalable name-based forwarding, named-data routing and in-network caching, have been widely explored and researched. However, to the best of our knowledge, the impact of this network abstraction on ICN applications has not been explored or well understood. The motivation of this dissertation is to address this research gap. Presumably, shifting from the IP\u27s channel abstraction, in which two endpoints must establish a channel to communicate, to the request for named data abstraction in ICNs, should simplify application mechanisms. This is not only because those mechanisms are no longer required to translate named-based requests to addresses of endpoints, but mainly because application mechanisms are no longer coupled with the connectivity characteristics of the channel. Hence, applications do not need to worry if there is a synchronous end-to-end path between two endpoints, or if a device along the path switches between concurrent interfaces for communication. Therefore, ICN architectures present a new and powerful promise to applications --- the freedom to stay in the information plane decoupled from connectivity. This dissertation shows that despite this powerful promise, the information and connectivity planes are presently coupled in today\u27s incarnations of leading ICNs by a core architectural component, the forwarding strategy. Therefore, this dissertation defines the role of forwarding strategies, and it introduces Information-Centric Transport (ICT) as a new architectural component that application developers can rely on if they want their application to be decoupled from connectivity. When discussing the role of ICT, we explain the importance of in-network transport mechanisms in ICNs, and we explore how those mechanisms can be scalable when generalized to provide broadly-applicable application needs. To illustrate our contribution concretely, we present three group communication abstractions that can evolve into ICTs: 1) Data synchronization of named data. This abstraction supports applications that want to maintain data consistency over time of a group\u27s shared dataset. 2) Push-like notifications for the latest named data. This abstraction supports applications that want to quickly notify and be notified about the latest content that was produced by a member(s) in the group. And 3) distributed named data fetching when the content is partitioned. This abstraction supports applications that their named data is partitioned and distributed in the group, and the names of content items in a partition cannot be generalized and hierarchically represented using one partition name. For each ICT, we provide examples of known applications that can use it, we discuss different mechanisms for implementation, and we evaluate selected implementations. We show how by relying on an ICT instead of a forwarding strategy, the tested applications can maintain sustainable communication in connectivities where IP tools fail or do not work well

    An algorithm for fast route lookup and update

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    Increase in routing table sizes, number of updates, traffic, speed of links and migration to IPv6 have made IP address lookup, based on longest prefix matching, a major bottleneck for high performance routers. Several schemes are evaluated and compared based on complexity analysis and simulation results. A trie based scheme, called Linked List Cascade Addressable Trie (LLCAT) is presented. The strength of LLCAT comes from the fact that it is easy to be implemented in hardware, and also routing table update operations are performed incrementally requiring very few memory operations guaranteed for worst case to satisfy requirements of dynamic routing tables in high speed routers. Application of compression schemes to this algorithm is also considered to improve memory consumption and search time. The algorithm is implemented in C language and simulation results with real-life data is presented along with detailed description of the algorithm
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