Network Operations and Internet Security @ UChicago

SDX: Software Defined Internet Exchange


We are developing an SDN exchange point (SDX), which aims to enable more expressive policies than conventional hop-by-hop, destination-based forwarding. Deploying software defined networking (SDN) at Internet exchange points (IXPs) offers new hope for solving long standing problems in interdomain routing. SDN allows direct expression of more flexible policies, and IXPs are central rendezvous points that are in the midst of a rebirth, making them a natural place to start.  At the SDX, ISPs can apply many diverse actions on packets based on multiple header fields, and distant networks can exercise “remote control” over packet handling. This flexibility enables applications such as inbound traffic engineering, redirection of traffic to middleboxes, wide-area server load balancing, and blocking of unwanted traffic. Supporting these applications requires effective ways to combine the policies of multiple ISPs.

We have developed an SDX controller that provides each ISP the abstraction of its own virtual switch and sequentially composes the policies of different ISPs into a single set of rules in the physical switches. It comprises a set of participant applications running on a runtime system built on top of Pyretic, as shown in figure below. The SDX runtime abstracts the details of the IXP from the participant ASes, who write applications based on their own view of the logical topology. The SDX runtime also composes distinct AS policies using sequential (“>>”) and parallel (“+”) composition operators; it also ensures that participants’ policies do not interfere or conflict with one another. The SDX controller can incorporate auxiliary information such as resource public key infrastructure (RPKI) records, route server information, and so forth to enable routing decisions that are based on a richer set of information than today’s BGP-based routing.


  • SDX: A Software Defined Internet Exchange
    Arpit Gupta (Georgia Institute of Technology), Laurent Vanbever (Princeton University), Muhammad Shahbaz (Georgia Institute of Technology), Sean P. Donovan (Georgia Institute of Technology), Brandon Schlinker (University of Southern California), Nick Feamster (Georgia Institute of Technology), Jennifer Rexford (Princeton University), Scott Shenker (UC Berkeley), Russ Clark (Georgia Institute of Technology), Ethan Katz-Bassett (University of Southern California)
    ACM SIGCOMM, Chicago, IL. August 2014.
  • SDX: A Software Defined Internet Exchange
    Nick Feamster (Georgia Tech), Jennifer Rexford (Princeton University), Scott Shenker (UC Berkeley), Dave Levin (University of Maryland), Russ Clark (Georgia Tech), Ron Hutchins, Josh Bailey (Google)
    Open Network Summit, Santa Clara, CA.  April 2013.


Other Resources


Nick Feamster presented the initial design for a software-defined Internet exchange (SDX) at the Open Network Summit in San Jose, CA.  The talk presents a vision for an SDN-based Internet exchange point and describes the initial deployment of SDX at ColoATL in Atlanta, GA.

A video of the talk is available from the ONS archives (registration required; see Research Track Part 2 on the “Tuesday” link).



Please contact us at: sdx AT gtnoise DOT net

One thought on “SDX: Software Defined Internet Exchange

  1. Pingback: “SDX: A Software Defined Internet Exchange Point” to Appear at SIGCOMM 2014 | GT Noise

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