Author: zihu

Categories
Software releases

Digit-1.1 release

Digit-1.1 has been released  (available at https://ant.isi.edu/software/tdns/index.htmlScreenshot from 2014-11-08 16:17:45).  Digit is a DNS client side tool that can perform DNS queries via different protocols such as UDP, TCP, TLS. This tool is primarily designed to evaluate the client side latency of using DNS over TCP/TLS, as described in the technical report “T-DNS: Connection-Oriented DNS to Improve Privacy and Security” (http://www.isi.edu/~johnh/PAPERS/Zhu14b/index.html).

A README in the package has detailed instructions about how to use this software.

Categories
Papers Publications

new conference paper “The Need for End-to-End Evaluation of Cloud Availability” in PAM 2014

The paper “The Need for End-to-End Evaluation of Cloud Availability” was published by PAM 2014 in Marina del Rey, CA (available at http://www.isi.edu/~zihu/paper/cloud_availability.pdf).

From the abstract:cloud_availability_blog

People’s computing lives are moving into the cloud, making understanding cloud availability increasingly critical. Prior studies of Internet outages have used ICMP-based pings and traceroutes. While these studies can detect network availability, we show that they can be inaccurate at estimating cloud availability. Without care, ICMP probes can underestimate availability because ICMP is not as robust as application-level measurements such as HTTP. They can overestimate availability if they measure reachability of the cloud’s edge, missing failures in the cloud’s back-end. We develop methodologies sensitive to five “nines” of reliability, and then we compare ICMP and end-to-end measurements for both cloud VM and storage services. We show case studies where one fails and the other succeeds, and our results highlight the importance of application-level retries to reach high precision. When possible, we recommend end-to-end measurement with application-level protocols to evaluate the availability of cloud services.

Citation: Zi Hu, Liang Zhu, Calvin Ardi, Ethan Katz-Bassett, Harsha Madhyastha, John Heidemann, Minlan Yu. The Need for End-to-End Evaluation of Cloud Availability. Passive and Active Measurements Conference (PAM). Los Angeles, CA, USA, March 2014.

Categories
Announcements Data

Complete IPv4 geolocation dataset now available

complete_geoloc_map

We recently finished the work of geolocating all IPv4 addresses and plotted a “complete IP geolocation map“.

This work is based on our previous IMC paper “Towards Geolocation of Millions of IP Addresses“, joint work of Zi Hu, John Heidemann, and Yuri Pradkin.

Processed data from this work is visible on our browsable web map.  The raw data from this effort is available through PREDICT or from the authors.

Categories
Papers Publications

New conference paper “Towards Geolocation of Millions of IP Addresses” at IMC 2012

The paper “Towards Geolocation of Millions of IP Addresses” was accepted by IMC 2012 in Boston, MA (available at http://www.isi.edu/~johnh/PAPERS/Hu12a.html).

From the abstract:

Previous measurement-based IP geolocation algorithms have focused on accuracy, studying a few targets with increasingly sophisticated algorithms taking measurements from tens of vantage points (VPs). In this paper, we study how to scale up existing measurement-based geolocation algorithms like Shortest Ping and CBG to cover the whole Internet. We show that with many vantage points, VP proximity to the target is the most important factor affecting accuracy. This observation suggests our new algorithm that selects the best few VPs for each target from many candidates. This approach addresses the main bottleneck to geolocation scalability: minimizing traffic into each target (and also out of each VP) while maintaining accuracy. Using this approach we have currently geolocated about 35% of the allocated, unicast, IPv4 address-space (about 85% of the addresses in the Internet that can be directly geolocated). We visualize our geolocation results on a web-based address-space browser.

Citation: Zi Hu and John Heidemann and Yuri Pradkin. Towards Geolocation of Millions of IP Addresses. In Proceedings of the ACM Internet Measurement Conference, p. to appear. Boston, MA, USA, ACM. 2012. <http://www.isi.edu/~johnh/PAPERS/Hu12a.html>

 

Categories
Publications Technical Report

New Tech Report “Towards Geolocation of Millions of IP Addresses”

We just published a new technical report “Towards Geolocation of Millions of IP Addresses”, available at ftp://ftp.isi.edu/isi-pubs/tr-680.pdf.

From the abstract:

Previous measurement-based IP geolocation algorithms have focused on accuracy, studying a few targets with increasingly sophisticated algorithms taking measurements from tens of vantage points (VPs). In this paper, we study how to scale up existing measurement-based geolocation algorithms like Shortest Ping and CBG to cover the whole Internet. We show that with many vantage points, VP proximity to the target is the most important factor affecting accuracy. This observation suggests our new algorithm that selects the best few VPs for each target from many candidates. This approach addresses the main bottleneck to geolocation scalability: minimizing traffic into each target (and also out of each VP) while maintaining accuracy. Using this approach we have currently geolocated about 24% of the allocated, unicast, IPv4 address-space (about 55% of the addresses in the Internet that can be directly geolocated).