Current Projects

Exploring the Challenges of Network Migration - An IPv6 Case Study and its Consequences. This is a joint project with Comcast and supported in part by Comcast and by NSF grant CNS-1116039. Its goals are to assess, understand, and encourage the adoption of IPv6. Specifically, as we rapidly approach the date at which the current set of IPv4 addresses will have been exhausted, i.e., in less than a year according to the latest estimates, migrating to IPv6 is becoming increasingly important. This migration is, however, largely dependent on ensuring that the current IPv4 Internet, and in particular its content, becomes itself accessible over IPv6. Tracking the extent to which this is happening is the main purpose of this project. This tracking is performed by a monitoring client that queries the Domain Name System (DNS) for IPv4 and IPv6 addresses (A and quad-A records) for a number of known sites. The list of sites queried includes the top one million (1M) web sites according to the ranking maintained by Alexa, and possibly additional sites beyond the top 1M.


Content is deemed IPv6 accessible if DNS returns a quad-A record for the site. Sites identified as being both IPv4 and IPv6 accessible are then queried for content, and deemed IPv4 and IPv6 reachable if the same content can be retrieved over both. The relative performance of content retrieval over IPv4 and IPv6 is then compared based on a succession of queries. One of the project's goals is to analyze this data to understand when, where and why differences exist between Ipv4 and IPv6 access, and how these should be addressed or used to foster a faster a migration to IPv6. In addition, in order to provide a more comprehensive perspective on the level of IPv6 adoption across the Internet, the monitoring software is being deployed at multiple locations. The goal is to ultimately make the information gathered across locations publicly available to facilitate research and evaluation by others.

Project Website

Related Publications



A Market Approach to Controlling the Proliferation of Internet Routes. This is a project aimed at developing mechanism to address the growth of core Internet routing tables.

The growth of core Internet routing tables is obviously a direct consequence of the growth of the Internet itself. However, it has been proceeding at a pace that far exceeds that of the Internet growth, and this is threatening the scalability of the Internet routing system, both in the short-term (most routers have hard limits on the number of routes they can store) and in the long-term (it out-paces the rate of improvement from technology itself). The main culprit behind this trend is the desire for individual “sites” to improve the reliability of their Internet connectivity; clearly a natural desire given the growing dependency on Internet connectivity. This desire for better reliability commonly manifests itself through multi-homing decisions, i.e., connectivity to the Internet through more than one provider to enjoy the benefits of greater path diversity, and herein lies the problem. When sites are multi-homed, their individual address sub-block are advertised by the different providers to which they connect, and this typically affects the ability of upstream providers to aggregate those routes; hence creating additional entries in core Internet routing tables.

In this project, we investigate market mechanisms to better redistribute the cost of additional routing entries caused by multi-homing to the sites responsible for those new entries. The hope is that this redistribution can help control the growth of routing tables or at least ensure that their growth is borne by those that are causing it and benefit from it.

The project also seeks to more broadly explore the use of market mechanisms to tackle a number of technical networking problems, including aspects related to promoting the adoption of those solutions.

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On the Economic Viability of Network Architectures. This is a joint project with Prof. Kartik Hosanagar from the Wharton Business School and Profs. Andrew Odlyzko and Zhi-Li Zhang from the University of Minnesota, which is funded by NSF under the FIND initiative (NSF grant CNS-0721610). The project has three main thrust areas aimed at assessing the economic viability of new network architectures:


  1. Investigate and quantify the potential benefits of key proposed architectural features such as virtualization, integration, and diversity;

  2. Explore when and why the existence of a formidable incumbent (today’s Internet) can affect the emergence of new technologies;

  3. Develop models that account for how the openness and flexibility of a network architecture can foster the adoption of new technology, and its ultimate success.

Project Website

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A Framework for Manageability in Future Routing Systems. This is a joint project with the University of Minnesota (Prof. Zhi-Li Zhang) and the University of Massachusetts (Prof. Lixin Gao) funded by NSF under the FIND initiative (NSF grant CNS-0627004). The project addresses fundamental questions on building manageability into routing systems for future Internet architectures. Its goals are two-fold: i) develop a framework for specifying, understanding, and evaluating what features should/could be "designed-in" into routing systems in support of manageability; and ii) evaluate design choices and trade-offs thereof in terms of performance and manageability.

Project Website

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