Transport Services
charter-ietf-taps-00-00

Conjointly, transport protocols such as SCTP, DCCP, MPTCP,
UDP-Lite and the LEDBAT congestion control mechanism extend
the set of transport services that are available to
applications, beyond those provided by TCP and UDP. For
example, SCTP provides potentially faster reliable delivery
for applications that can accept blocks of data out of order,
and LEDBAT provides low-priority "scavenger" communication.

For an application programmer, it is hard to use protocols
other than TCP or UDP: most network stacks only support TCP
and UDP, many firewalls only pass TCP and UDP, and requiring
other transport protocols risks having an application not
work in many environments. Applications, therefore, must
always be able to fall back to TCP or UDP. Further, different
protocols can provide the same services in different ways.
Layering decisions must be made (for example, whether a
protocol is used natively or tunneled through UDP).

Because of these complications, programmers often resort
to either using TCP or implementing their own customized
solution over UDP. That can result in applications
re-implementing features already available elsewhere,
and chances of benefiting from other transport protocols
are lost.

There are many ways in which this problem could be addressed;
while it may not yet be clear what the best way forward could
be, any approach to provide a richer set of transport services
to applications will have to begin with the identification of
the services that current transport protocols provide.

The Working Group will:

• Identify services provided by existing IETF transport protocols
  and congestion control mechanisms. The resulting document will
  provide guidance on making a choice among available mechanisms
  and protocols to obtain a certain transport service.

• Specify a subset of those services identified in item 1, which
  end systems supporting TAPS need to provide and provide guidance
  on choosing among available mechanisms and protocols to obtain
  a given transport service.

• Specify experimental mechanisms to deliver a transport service.
  This will explain how to select and engage a protocol, and how
  to discover the availability of protocols on an interface (both
  end system and path support), in order to provide a basis for
  incremental deployment.

The Working Group will coordinate closely with other Working
Groups and IRTF Research Groups.

The following topics are out of scope of this Working Group:

• Quality-of-Service (QoS) and tunneling mechanisms and services

• Definition of new encapsulations and tunneling mechanisms

Milestones:
M7: Submit summary of the services provided by IETF transport
protocols and congestion control mechanisms to IESG.
M13: Submit end system transport services to IESG.
M14: Submit specification of how the transport services can be
provided to IESG.