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IAB Workshop on Stack Evolution in a Middlebox Internet (semiws)

Team Name IAB Workshop on Stack Evolution in a Middlebox Internet
Acronym semiws
State Active
Additional resources RFC 7663: Report from the IAB Workshop on Stack Evolution in a Middlebox Internet

Group description

26-27 January 2015 – ETH Zürich, Switzerland

The Internet’s transport layer has ossified, squeezed between narrow interfaces (from BSD sockets to pseudo-transport over HTTPS) and increasing in-network modification of traffic by middleboxes that make assumptions about the protocols running through them. This ossification makes it difficult to innovate in the transport layer, through the deployment of new protocols or the extension of existing ones. At the same time, emerging applications require functionality that existing protocols can provide only inefficiently, if at all.

To begin to address this problem, the Internet Architecture Board (IAB), within the scope of its IP Stack Evolution Program, is organizing a workshop to discuss approaches to de-ossifying transport, especially with respect to interactions with middleboxes and new methods for implementing transport protocols. Recognizing that the end-to-end principle has long been compromised, we start with the fundamental question of matching paths through the Internet with certain characteristics to application and transport requirements. Which paths through the Internet are actually available to applications? Which transports can be used over these paths? How can applications cooperate with network elements to improve path establishment and discovery? Can common transport functionality and standardization help application developers to implement and deploy such approaches in today’s Internet? Could cooperative approaches give us a way to rebalance the Internet back toward its end-to-end roots?


For this workshop we would like to consider topics that speak to these questions, including the following:

  • Development and deployment of transport-like features in application-layer protocols
  • Methods for discovery of path characteristics and protocol availability along a path
  • Methods for middlebox detection and characterization of middlebox behavior and functionality
  • Methods for NAT and middlebox traversal in the establishment of end-to-end paths
  • Mechanisms for cooperative path-endpoint signaling, and lessons learned from existing approaches
  • Economic considerations and incentives for cooperation in middlebox deployment

We will explicitly focus on approaches that are incrementally deployable within the present Internet.

The outcome of the workshop will be architectural and engineering guidance on future work in the area, published as an IAB workshop report, based on discussion of proposed approaches; future work will be pursued within the IAB Stack Evolution Program. We will also explore possible areas for standardization, e.g. new protocols that separate signaling to and from on-path devices and common transport semantics from the rest of the transport protocol; and for general guidance, e.g. how transports as well as middleboxes can be designed and deployed to achieve these goals.

Position Papers of Attendees

See the Materials tab on this page.

  • Black, D.: UDP Encapsulation: Framework Considerations
  • Blanchet, M.: Implications of Blocking Outgoing Ports Except Ports 80 and 443
  • Briscoe, B.: Tunneling Through Inner Space
  • Calvert, K.: Refactoring Transport for the Next Century
  • Cheshire, S.: Restoring the Reputation of the Much-Maligned TCP
  • Ding, A. Y., Korhonen, J., Savolainen, T., Liu. Y., Kojo, M., Tarkoma, S. and Schulzrinne, H.: Reflections on Middlebox Detection Mechanism in IPv6 Transition
  • Edeline, K. and Donnet, B.: On a Middlebox Classification
  • Hardie, T.: Network Function Virtualization and Path Character
  • Huici, F., Raiciu, C. and Honda, M.: In-Network Processing, User-Level Stacks and the Future of Internet Evolution
  • Huitema, C.: The Secure Transport Tussle
  • Iyengar, J.: Oh End-to-End, Where Art Thou?
  • Nádas, S. and Loreto, S: Middleboxes in Cellular Networks
  • Nottingham, M. and Ponec, M.: UDP-based Application Layer Protocol Recipes to the Rescue
  • Perkins, C. and McQuistin, S.: Reinterpreting the Transport Protocol Stack to Embrace Ossification
  • Raiciu, C., Olteanu, V., and Stoenescu, R.: Good cop, Bad Cop: Forcing Middleboxes to Cooperate
  • Reddy, T., Patil, P., Wing, D. and Versteeg, B.: WebRTC UDP Firewall Traversal
  • Rescorla, E.: Notes on Security Models for Transport Evolution
  • Schmidt, P. and Enghardt, T.: Cross-Layer Coordination: Let’s Talk About Intentions
  • Welzl, M., Fairhurst, G., and Ros, D.: Ossification: a result of not even trying?
  • Williams, B.: IAB SEMI Position Paper

Workshop Slides

See the Materials tab on this page.

  • Welcome
  • Introductions
  • Technical Sessions: the bigger picture, the role and rule of middleboxes, and unbreaking transport
  • Working Sessions (day 2): SPUD, DTLS, and Action Items

Additional Reading

Submission Instructions

Attendance at the workshop is by invitation. Prospective participants are invited to submit short (i.e., about two pages) position papers outlining their views on one or more topics related to the scope of the workshop. Position papers will be published on the IAB website.

Travel Grants

The Internet Society will sponsor a very limited number of travel grants (including economy class airfare, hotel costs and incidental expenses) for invited attendees who have no other source of travel funding.


The workshop will take place at the ETH Zurich central campus main building, Rämistrasse 101, 8006 Zürich, Switzerland.

Public transport in Zurich is the recommend way to get around. The main building is located directly at the ETH-Universitätsspital tram stop on lines 6, 9, and 10, and at the top of the Polybahn funicular railway (middle right of

If cost is of any concerns, taxis are generally to be avoided in Zurich; a taxi from the airport into the city will cost about CHF 60.- to CHF 80.- one way, depending on traffic. Further parking in the city center is severely limited and quite expensive, as well, so it’s not recommended to rent a car, either.


There are no block reservations for the workshop; the following hotels (~CHF 150-250 a night) are close enough to the venue to walk:

Hotel Marta

Hotel Plattenhof

Hotel Sunnehus

Hotel Du Théâtre

  • Seilergraben 69
  • +41 44 267 26 70

Central Plaza Hotel

Technical Program Committee

  • Gorry Fairhurst, University of Aberdeen, UK
  • Matthew Ford, Internet Society, UK
  • Joe Hildebrand, Cisco, USA
  • Mirja Kühlewind, ETH Zurich, Switzerland
  • Eliot Lear, Cisco, Switzerland
  • Martin Stiemerling, University of Applied Science Darmstadt, Germany
  • Brian Trammell, ETH Zurich, Switzerland

Sponsored by the Internet Architecture Board, the Internet Society, and ETH Zürich. Mirja Kühlewind and Brian Trammell, General Chairs.