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CAIDA Skitters across the Global Network

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K.C. Claffy

Daniel McRobb
Caimis, Inc.

Andre Broid
Marina Fomenkov
Bradley Huffaker
Sean McCreary
David Moore

T he Internet's infrastructure is often compared to a circulatory system, equating arteries with backbone providers and capillaries with the Internet Service Providers (ISPs) that supply homes and businesses with the "last mile" Internet connections. Data streams flow through the Internet, much like blood in the circulatory system, and the Internet's infrastructure, like the human heart, must be robust to support the intricate system. Perhaps no one has a better perception of the Internet's complex infrastructure than K.C. Claffy and the team of scientists with the Cooperative Association for Internet Data Analysis (CAIDA), which Claffy co-founded in 1997. The CAIDA team at SDSC works toward greater cooperation among the commercial, government, and research sectors to engineer and maintain a robust, scalable global Internet infrastructure.



caida1 Figure 1. An Internet Roadmap
By combining peering richness and geographic information, this skitter graph reveals the highly connected nature of autonomous systems, each of which approximately maps to an Internet Service Provider (ISP). Of the top 15 autonomous systems, 14 are based in the United States and one is based in Canada. While ISPs in Europe and Asia have many peering relationships with ISPs in the United States, there are few direct links between ISPs in Asia and Europe. Link color reflects out-going paths, from lowest (blue) to highest (yellow).
Perhaps the most popular of CAIDA's research tools is skitter, which is designed to provide the understanding necessary to discover more efficient pathways throughout the Internet. CAIDA's skitter initiative helps further fundamental research efforts, primarily funded by CAIDA members, the National Science Foundation, and DARPA's Next Generation Internet program. At its most fundamental level, skitter measures forward Internet Protocol (IP) paths by sending out small packets of data from one source to many destinations.


A specific infrastructure application of the skitter initiative involves evaluating the selection of root domain name server (DNS) locations with respect to how well they are serving their client user base. The techniques and methodology are relevant beyond the DNS system and can be applied to location research for any type of strategic infrastructure server.

To develop the skitter tool and strengthen it for industry use, the UC San Diego Office of Technology Transfer and Intellectual Property Services recently approved the licensing of the skitter tool to Caimis, Inc., which derived its name from CAIDA Monitoring and Networking Internet Solutions. Caimis is now using CAIDA's results from certain skitter research efforts to develop network monitoring and management products for providers and enterprises around the world.

CAIDA's skitter initiative resulted in the Caimis product skping, a Unix-based graphical tool for measuring round-trip time and packet loss to a single destination. Developed by Daniel McRobb, former CAIDA network engineer and Caimis chief architect, skping enhances the popular "ping" utility, a tool that measures latency characteristics between two hosts.

Named for the submariners' term for the sound of a returned sonar pulse, "ping" in the networking world means "to get the attention of" or "to check for the presence of" another party online. Ping operates by sending a packet to a designated address and waiting for a response. Unlike ping's text-based interface, however, skping graphically depicts both historic and real-time views of performance to specific network destinations. With skping, the user can quickly display a graphic that summarizes up to 15 minutes of data.

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K.C. Claffy (1999): Internet measurement and data analysis: Topology, workload, performance, and routing statistics. NAE 99 workshop paper.

K.C. Claffy (1999): Internet tomography. Nature: Web Matters, January 7, 1999.


A similar Caimis product that emerged from CAIDA's skitter code library is sktrace. While skping provides an intuitive summary of network performance, sktrace does a "hop-by-hop" analysis of an entire path from source to destination. Sktrace displays a scatter plot of the round-trip time and a listing of each hop in the path, including multiple paths if the path changes over time.

"The timing is ripe for Caimis to offer commercial solutions to address challenges faced by service providers, not the least of which are inter-ISP traffic engineering, analysis, and problem resolution," Claffy said. "CAIDA has developed a number of research tools to map and visualize the Internet, and now companies such as Caimis can take some of these prototypes, like skitter, to the next level of development. In return, Caimis tools will be available to CAIDA researchers to support analyses of Internet performance and topology."

This cooperative effort fits CAIDA's mission to promote collaboration among academia, government agencies, and industry. "Our priority is to ensure the engineering and maintenance of a robust, scalable global Internet infrastructure, which consists of a complex array of telecommunications carriers and providers," Claffy said. "It's a very difficult infrastructure to analyze diagnostically except within the borders of an individual network. However, CAIDA's primary objective is to provide insights into the overall health and scalability, which are critical to the Internet's evolution." --KMB *

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