Use Cases for a Substrate Protocol for User Datagrams (SPUD)

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Last updated 2016-09-19 (latest revision 2016-03-18)
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This document identifies use cases for explicit cooperation between endpoints and middleboxes in the Internet under endpoint control. These use cases range from relatively low level applications (improving the ability for UDP-based protocols to traverse firewalls) through support for new transport services (in-flow prioritization for graceful in-network degradation of media streams). They are intended to provide background for deriving the requirements for a Substrate Protocol for User Datagrams (SPUD), as discussed at the IAB Stack Evolution in a Middlebox Internet (SEMI) workshop in January 2015 and the SPUD BoF session at IETF 92 in March 2015.


Mirja K├╝hlewind (
Brian Trammell (

(Note: The e-mail addresses provided for the authors of this Internet-Draft may no longer be valid.)