Catálogo de publicaciones - libros

IPv6 provides an expanded address space to satisfy the future Internet requirements. In this paper we compare and analyze one-month measurements of the end-to-end IPv6 delay and hopcount between 26 testboxes of the RIPE TTM project with the corresponding parts in IPv4 network. By comparing IPv6 and IPv4 paths, we focus on problems that are only present in the IPv6 paths. In those poorly performing IPv6 paths, we run traceroute with the path maximum transmission unit (MTU) discovery to identify the problems and their causes.

Emerging network monitoring infrastructures capture packet-level traces or keep per-flow statistics at a set of distributed vantage points. Today, distributed monitors in such an infrastructure do not coordinate monitoring effort, which both can lead to duplication of effort and can complicate subsequent data analysis. We argue that nodes in such a monitoring infrastructure, whether across the wide-area Internet, or across a sensor network, should coordinate effort to minimize resource consumption. We propose space-efficient data structures for use in gossip-based protocols to approximately summarize sets of monitored flows. With some fine-tuning of our methods, we can ensure that all flows observed by at least one monitor are monitored, and only a tiny fraction are monitored redundantly. Our preliminary results over a realistic ISP topology demonstrate the effectiveness of our techniques on monitoring tens of thousands of point-of-presence (PoP) level network flows. Our methods are competitive with optimal off-line coordination, but require significantly less space and network overhead than naive approaches.

The increasing popularity of Peer-to-Peer (P2P) networks has led to growing interest in characterizing their topology and dynamics [1,2,3,4], essential for proper design and effective evaluation. A common technique is to capture topology snapshots using a crawler. However, previous studies have not verified the accuracy of their captured snapshots. We present techniques to measure the inaccuracy of topology snapshots, quantify the effects of unreachable peers and crawling speed, and explore the impact of snapshot accuracy on derived characterizations.

Accurate timestamps on both the sender and the receiver side are crucial for one-way delay (OWD) measurements. Traditionally, the methods of (i) peering with NTP servers, and (ii) connecting to a time source directly, have been used to maintain the accuracy of a measurement system clock. However, it has became clear that such methods suffer from errors to different extents.

We propose a practical technique for the identification of lossy network links. Our scheme is based on a function that computes the likelihood of each link to be lossy. This function mainly depends on the number of times a link appears in lossy paths and on the relative loss rates of these paths. Preliminary simulation results show that our solution achieves accuracy comparable to statistical methods (e.g. Bayesian) at significantly lower running time.

The tasks of measurement and data transport are often treated independently, but we believe there are benefits to bringing them together. This paper proposes the simple idea of a transport agent to encapsulate useful data within probe packets in place of useless padding.