Archive for the 'Routing' Category

Twelve Years in the Evolution of the Internet Ecosystem

Tuesday, April 10th, 2012 by Amogh Dhamdhere

Our recent study of the evolution of the Internet ecosystem over the last twelve years (1998-2010) appeared in the IEEE/ACM Transactions on Networking in October 2011. Why is the Internet an ecosystem? The Internet, commonly described as a network of networks, consists of thousands of Autonomous Systems (ASes) of different sizes, functions, and business objectives that interact to provide the end-to-end connectivity that end users experience. ASes engage in transit (or customer-provider) relations, and also in settlement-free peering relations. These relations, which appear as inter domain links in an AS topology graph, indicate the transfer of not only traffic but also economic value between ASes. The Internet AS ecosystem is highly dynamic, experiencing growth (birth of new ASes), rewiring (changes in the connectivity of existing ASes), as well as deaths (of existing ASes). The dynamics of the AS ecosystem are determined both by external business environment factors (such as the state of the global economy or the popularity of new Internet applications) and by complex incentives and objectives of each AS. Specifically, ASes attempt to optimize their utility or financial gains by dynamically changing, directly or indirectly, the ASes they interact with.

The goal of our study was to better understand this complex ecosystem, the behavior of entities that constitute it (ASes), and the nature of interactions between those entities (AS links). How has the Internet ecosystem been growing? Is growth a more significant factor than rewiring in the formation of new links? Is the population of transit providers increasing (implying diversification of the transit market) or decreasing (consolidation of the transit market)? As the Internet grows in its number of nodes and links, does the average AS-path length also increase? Which ASes engage in aggressive multihoming? Which ASes are especially active, i.e., constantly adjust their set of providers? Are there regional differences in how the Internet evolves?

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NASA’s recent DNSSEC snafu and the checklist

Thursday, February 16th, 2012 by kc

Reading about NASA’s recent DNSSEC snafu, and especially Comcast’s impressively cogent description of what went wrong (i.e., a mishap that seems way too easy to ‘hap’), I’m reminded of the page I found most interesting in The Checklist Manifesto:

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Exhausted IPv4 address architectures

Tuesday, May 3rd, 2011 by kc

In light of available data on global IPv6 deployment, ISPs, and those who build equipment for them, have already accepted that multi-level network address translation (NAT, between IPv4 and IPv6 networks) is here for the foreseeable future, with all its limits on end-to-end reachability and application functionality, and its required unscalable per-protocol hacks. Whether “carrier-grade” NAT (CGN) technology supports a transition to IPv6 or becomes the endgame itself is irrelevant to the planning horizon of public companies, who must now develop sustainable business models that accommodate, if not support, IPv4 scarcity. I’ve heard a few notable predicted outcomes from engineers in the field.

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Unsolicited Internet Traffic from Libya

Wednesday, March 23rd, 2011 by Emile Aben

Amidst the recent political unrest in the Middle East, researchers have observed significant changes in Internet traffic and connectivity. In this article we tap into a previously unused source of data: unsolicited Internet traffic arriving from Libya. The traffic data we captured shows distinct changes in unsolicited traffic patterns since 17 February 2011.

Most of the information already published about Internet connectivity in the Middle East has been based on four types of data:

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Caidagram: visualizing geographically annotated Internet measurements

Monday, February 28th, 2011 by Claudio Squarcella

I post this article to describe the results of my five month visit to CAIDA and UC San Diego, and to thank the organizations that collaborated to make this work possible.

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my first “Future Internet Architecture” PI meeting

Wednesday, January 5th, 2011 by kc

Among the interesting meetings I attended in 2010 was the principal investigators (PI) meeting for NSF’s new “Future Internet Architecture” (FIA) program. The FIA program builds on the successes of NSF’s previous Future Internet Design (FIND) program, the recommendations of a review panel, and a community summit in October 2009. (The FIND program itself has been integrated into NSF’s new Network Science and Engineering research program, while the four FIA teams are attempting to implement some of the ideas developed thus far.) CAIDA is participating in one of these projects — Named Data Networking (NDN), led by Van Jacobson at Xerox Parc and Lixia Zhang at UCLA. (Background links to 2010 technical report describing the proposed architecture, Van’s August 2006 video lecture and 2009 ACM Queue Q&A on NDN ideas.)

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IP-AS mappings

Wednesday, July 28th, 2010 by Amogh Dhamdhere

We have performed an analysis of the IP-AS mapping obtained from Routeviews/RIPE collectors.

A crucial step in various research efforts that study the Internet infrastructure is to map an IP address to the Autonomous System (AS) to which it is assigned. The most common approach to map IP addresses to ASes is by using BGP table dumps from public repositories such as Routeviews and RIPE. We assign “ownership” of an IP address to the AS that originates the longest BGP prefix that matches the IP address. Routeviews and RIPE, however, have multiple collectors, each of which peers with a diverse set of ASes. Consequently, the IP-AS mapping obtained by using the BGP table dump from one collector could be different from that obtained from a different collector. The obvious solution is to aggregate views from as many vantage points as possible to obtain the most complete IP-AS mapping possible. In practice, however, it is common to use data from just one or two collectors, as it greatly simplifies the process of collecting and pre-processing data. The goal of our analysis is to compare different collectors, in terms of the different metrics that we are interested in, viz. address space coverage, IP-AS mapping, unique ASes, unique prefixes, unique more specific prefixes, AS links, and AS paths. Further, we study the utility of adding data from more collectors, in terms of the resulting change in the aforementioned metrics. Finally, we compare the IP-AS mapping from Routeviews and RIPE tables with that obtained from Team Cymru’s whois service.

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‘academic’ thoughts about a ‘future Internet’

Monday, October 12th, 2009 by kc

This post is our submitted response to NSF’s call for expressions of interest in the Future Internet Architectures summit, which i am attending this week.

What scientific contributions will you bring to the discussion about Future Internet architectures?

As scientists, we are compelled to explore how the peculiar structure relates to the function(s) of complex networks. Many complex networks in nature share the peculiar structural character of the Internet, but they also manifest phenomenal behavior: they efficiently route information without any observable routing protocol overhead. This achievement is currently beyond the reach of man-made networks. The Internet still uses a 30-year old routing architecture with fundamentally unscalable overhead requirements.  Yet in those 30 years, the Internet’s inter-domain topology has evolved toward a structure for which nature has superior routing technology, if only we can figure out how to use it!

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spoofer: measure your network’s hygiene!

Sunday, April 5th, 2009 by kc

Update: In May 2015, ownership of Spoofer transferred from MIT to CAIDA

We are studying an empirical Internet question central to its security, stability, and sustainability: how many networks allow packets with spoofed (fake) IP addresses to leave their network destined for the global Internet? In collaboration with MIT, we have designed an experiment that enables the most rigorous analysis of the prevalence of IP spoofing thus far, and we need your help running a measurement to support this study.

This week Rob Beverly finally announced to nanog an update to spoofer he’s been working on for a few months. Spoofer is one of the coolest Internet measurement tool we’ve seen in a long time — especially now that he is using Ark nodes as receivers (of spoofed and non-spoofed packets), giving him 20X more path coverage than he could get with a single receiver at MIT.

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what percentage of traffic on the Internet is peer-to-peer file sharing?

Sunday, February 8th, 2009 by kc

I get this question as often as I get any question about the Internet. finally, a visiting intern Mia Zhang from Beijing Jiaotung University has done a thorough literature roundup, extracting the best available data pertinent to this question that she could find in the public domain.

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