Measuring load-balanced paths in the Internet

2009 5th International Conference on Testbeds and Research Infrastructures for the Development of Networks & Communities and Workshops, 2009

There is a long line of research on measuring the Quality of Service (QoS) path characteristics of the Internet, such as available bandwidth, path capacity, packets reordering, delay and jitter. Most of the measurement techniques are based on active probing using pairs or trains of packets. The packets are either transmitted back-to-back or at a desired spacing (e.g., to achieve a certain rate). In most cases, one-way active probing techniques are preferred over round trip measurements as they gather less measurement noise.

2008

ABSTRACT The global Internet routing infrastructure is a large scale distributed system where routing changes occur all the time. While prior work on Internet routing dynamics examined routing stability to individual destinations, in this paper we study the routing stability of the Internet as a whole. We use the observed changes in the number of routes over each ASAS link as a metric and measure such changes from multiple vantage points over a period of one year.

International Journal of Network Management, 2004

2012

Traceroute is a popular tool that has many applications in network troubleshooting and mapping. We propose in this paper a six-step methodology for creating a more efficient profile-based probing strategy. The basic idea behind our methodology is examining how often routing changes occur in the routing path at the different times of the day. This helps in giving a high probing weight for parts of the routing path that change frequently while lower probing weight is assigned for parts that change rarely in the different time periods of the day.

Recent work on media streaming has proposed to exploit path diversity, i.e., the use of multiple endto-end paths, as a means to obtain better performance. The best performance is achieved when the various paths are independent in the sense that the two paths do not share a Point of Congestion (PoC). However, topologies used in media streaming applications do not meet the assumption of Inverted-Y or Y topologies made by prior work on detecting shared PoC. In this paper, we propose a new technique called CD-DJ (Correlating Drops and Delay Jitter) which solves this problem. CD-DJ is better than earlier solutions for three main reasons. First, CD-DJ overcomes the clock synchronization problem and can work with most topologies relevant to applications. Second, it provides applications with an estimate of the fraction of packet drops caused by shared PoCs. This information is more useful than a "yes/no" decision for media streaming applications because they can use it to choose a path based on the level of shared congestion. Third, CD-DJ makes the estimation by correlating bursts of packet drops in conjunction with the correlation of delay jitter in a novel way. A key contribution of our work is our evaluation methodology. We use a novel overlaybased method to evaluate our technique extensively using about 800 hours of experimental traces from Planetlab, a global overlay network. Our results indicate that CD-DJ calculates estimates which are at least within a factor of 0.8 of the actual fraction of shared drops for 80 − 90% of the flows. We also illustrate the advantage of using CD-DJ with a simple streaming video application.

ACM SIGCOMM Computer Communication Review, 2006

Extensive measurement studies have shown that end-to-end Internet path performance degradation is correlated with routing dynamics. However, the root cause of the correlation between routing dynamics and such performance degradation is poorly understood. In particular, how do routing changes result in degraded end-to-end path performance in the first place? How do factors such as topological properties, routing policies, and iBGP configurations affect the extent to which such routing events can cause performance degradation? Answers to these questions are critical for improving network performance.In this paper, we conduct extensive measurement that involves both controlled routing updates through two tier-1 ISPs and active probes of a diverse set of end-to-end paths on the Internet. We find that routing changes contribute to end-to-end packet loss significantly. Specifically, we study failover events in which a link failure leads to a routing change and recovery events in which a l...

Networks and Heterogeneous Media, 2006

The Internet's layered architecture and organizational structure give rise to a number of different topologies, with the lower layers defining more physical and the higher layers more virtual/logical types of connectivity structures. These structures are very different, and successful Internet topology modeling requires annotating the nodes and edges of the corresponding graphs with information that reflects their network-intrinsic meaning. These structures also give rise to different representations of the traffic that traverses the heterogeneous Internet, and a traffic matrix is a compact and succinct description of the traffic exchanges between the nodes in a given connectivity structure. In this paper, we summarize recent advances in Internet research related to (i) inferring and modeling the router-level topologies of individual service providers (i.e., the physical connectivity structure of an ISP, where nodes are routers/switches and links represent physical connections), (ii) estimating the intra-AS traffic matrix when the AS's router-level topology and routing configuration are known, (iii) inferring and modeling the Internet's AS-level topology, and (iv) estimating the inter-AS traffic matrix. We will also discuss recent work on Internet connectivity structures that arise at the higher layers in the IP/TCP protocol stack and are more virtual and dynamic; e.g., overlay networks like the WWW graph, where nodes are web pages and edges represent existing hyperlinks, or P2P networks like Gnutella, where nodes represent peers and two peers are connected if they have an active network connection. Here, an autonomous system (AS) or autonomous domain is a group of routers and networks managed by a single organization. In turn, an Internet Service Provider (ISP) can consist of a single AS or of a group of ASes, but for simplicity, we will use the terms AS and ISP indistinguishably throughout this paper. The TCP/IP protocol stack as a whole and IP in particular are able to hide from the user much of the enormous complexity associated with controlling this diverse set of networked resources and coordinating the actions among the many competing ISPs. By providing the mechanisms necessary to knit together diverse networking technologies and ASes into a single virtual network (i.e., a network of networks, or "Internet"), they ultimately guarantee seamless connectivity and reliable communication between sending and receiving hosts, irrespective of where in the network they are.

Computer Networks, 2011

Internet-wide services and applications depend on accurate information about the internal network state to deliver good performance to end-users. However, today's Internet does not provide such information explicitly and a number of systems have been recently proposed and implemented to provide a shared measurement infrastructure for distributed applications. The goal of this work is to demonstrate that without any new measurement infrastructure or active probing we obtain composite performance estimates from AS-by-AS segments and the estimates are as good as (or even better than) those from existing estimation methodologies that use on-demand, customized active probing. The key idea behind scaling measurements to the size of the Internet is to take advantage of the known underlying structure of the network.

2015

For more than 25 years now, traceroute has demonstrated its supremacy for network-path measurement, becoming the most widely used Internet path diagnosis tool today. A major limitation of traceroute when the destination is not controllable by the user is its inability to measure reverse paths, i.e., the path from a destination back to the source. Proposed techniques to address this issue rely on IP address spoong, which might lead to security concerns. In this paper we introduce and evaluate DisNETPerf, a new tool for locating probes that are the closest to a distant server. Those probes are then used to collect data from the server point-of-view to the service user for path performance monitoring and troubleshooting purposes. We propose two techniques for probe location, and demonstrate that the reverse path can be measured with very high accuracy in certain scenarios.

2014 IFIP Networking Conference, 2014

Most current models of the internet rely on knowledge of the degree distribution of its core routers, which plays a key role for simulation purposes. In practice, this distribution is usually observed directly on maps known to be partial, biased and erroneous. This raises serious concerns on the true knowledge one may have of this key property. Here, we design an original measurement approach targeting reliable estimation of the degree distribution of core routers, without resorting to any map. It consists in sampling random core routers and precisely estimate their degree thanks to probes sent from many distributed monitors. We run and assess a large-scale measurement following this approach, carefully controlling and correcting bias and errors encountered in practice. The estimate we obtain is much more reliable than previous knowledge, and it shows that the true degree distribution is very different from all current assumptions.