What is Transit Portal

Transit Portal (TP) (aka BGP-Mux) is a system that enables safe, secure, and tightly controlled access for researchers and educators to the Internet routing system. The system is in part funded by grants from NSF and GENI.

The project, from Georgia Institute of Technology and University of Southern California, fosters Internet research and innovation. Traditionally, the barriers to conduct Internet routing experiments hindered progress. To experiment with novel routing ideas or to understand aspects of the current routing ecosystem, researchers need the ability to actively participate in this ecosystem by emulating an autonomous system (AS). The Transit Portal testbed is the first system to solve this problem once for all qualified researchers. The testbed can multiplex multiple simultaneous research experiments, each of which independently makes routing decisions and sends and receives traffic. The Transit Portal has enabled research that appeared at top academic and industrial conferences. Without this testbed, none of this research would have been evaluated on the actual Internet, blunting its impact.

Now, the generous hosting of the project by AMS-IX allows the testbed to peer with hundreds of ASs, greatly expanding the Transit Portal's connectivity and enabling new classes of research that could not be done previously. This peering also serves as a model for future expansion of the testbed. By giving researchers around the world an easy but safe way to conduct BGP-based experiments, the Transit Portal testbed, in cooperation with AMS-IX, will inspire transformational research on Internet routing.


The long-term goal of the TP system is to enable on-demand, safe, and controlled access to the Internet routing ecosystem for researchers and educators:

  • TP for researchers. Today, it's hard for researchers to conduct wide-area routing experiments. To perform a routing experiment, a research institution has to obtain Internet numbered resources and establish relations with upstream networks. TP eliminates these obstacles and provides for researchers controlled on-demand access to Internet routing ecosystem.
  • TP for educators. Educators can use the TP infrastructure in teaching students the Internet routing architecture. The students can obtain access to live monitoring BGP sessions to multiple ISPs.

The TP system can be used for multiple Internet routing studies concurrently. Presently, the TP system is used by LIFEGUARD, a system for automatic failure localization and remediation. The system monitors Internet paths and locates failures using ping and traceroute, combined with novel tools. If it detects a data-plane failure on routes to the testbed and the Internet routing system is not responding to the failure, LIFEGUARD uses TP and AS-PATH stuffing to see if it is possible to re-route the traffic.

Result Publication

The core results of the experiments using TP must be published in publicly accessible documents. Detailed data produced by experiments, such as ping and traceroute command outputs, must be shared with researchers in accredited higher education institutions.

Experimentation Practices and Conditions

Internet routing system supports connectivity between millions of people. The TP system must ensure that experiments produce no noticeable impact on the Internet. The TP system will apply the following rules to all experiments:

  • Prefix origination. The TP system will announce only the prefixes directly under the TP system control. This ensures that only the Internet traffic to the prefix owned by TP is affected. The announcement of any other prefix is mitigated by filtering at both the TP nodes and all the direct upstream networks of the TP system.
  • Autonomous System origination. The TP system will announce BGP messages with AS-PATH that starts only with the AS number that is in directly under the TP system control. This rule ensures that BGP monitoring systems are minimally affected.
  • Update rate. The TP system will limit the rate of BGP messages, such that each BGP peer of the system will receive at most 10 announcements per hour for each TP prefix.
  • Opt-out policy. Where possible, an experiment must offer to remote networks an opt-out option. For instance, if the experiment is measuring reachability to networks in the Internet, such networks should be given an opt-out policy. The opt-out must be offered in the Internet operator forums, such as NANOG mailing list.

Technical Coordination
Experiments must be coordinated with operator community using NANOG mailing list. The TP system is operated by researchers at Georgia Institute of Technology, University of Southern California, and Universidade Federal de Minas Gerais. In a very unlikely event of TP sending BGP announcements that are not consistent with the policies described above, please email the team immediately, at bgpmux-noc (at gtnoise.net).