Thanks for working on this. Looks go to me. Looking forward to actually
do the work in a w-g!
Mirja
On 27.08.2014 00:27, Aaron Falk wrote:
See charter rev below. Change highlights:
- reverted to earlier 2nd doc description
- added back 3rd doc milestone
- minor cleanup
I'm only attaching the diff to the last rev because it's rather a pain
to generate the other one.
--aaron
Transport Services (taps)
Most Internet applications make use of the Transport Services provided
by TCP (a reliable, in-order stream protocol) or UDP (an unreliable
datagram protocol). We use the term "Transport Service" to mean an
end-to-end facility provided by the transport layer that can only be
correctly provided with information from the application. This
information may be provided at design time, compile time, or run time
and may include guidance from the application on whether the facility in
question is required or simply a preference by the application. Four
examples of Transport Services are reliable delivery, no guarantee of
order preservation, content privacy to in-path devices, and minimal latency.
Transport protocols such as SCTP, DCCP, WebSockets, MPTCP, and UDP-Lite
and the LEDBAT congestion control mechanism extend the set of available
Transport Services beyond those provided to applications by TCP and UDP.
For example, SCTP provides potentially faster (than TCP) reliable
delivery for applications because it can accept blocks of data out of
order, and LEDBAT provides low-priority "scavenger" communication.
However, application programmers face difficulty when they use protocols
other than TCP or UDP. Most network stacks ship with only TCP and UDP as
transport protocols. Many firewalls only pass TCP and UDP and some only
support HTTP over TCP. As a result, using other transport protocols or
building a new protocol over raw sockets risks having an application not
work in many environments. Applications, therefore, must always be able
to fall back to TCP or UDP, or even HTTP in many cases, and once the
application programmer has committed to making an application work on
TCP or UDP or HTTP, there is little incentive to try other transport
protocols before falling back. 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 HTTP or implementing their own customized "transport services"
over UDP. When application developers re-implement transport features
already available elsewhere they open the door to problems that simply
using TCP would have avoided and ensure that the applications can't
benefit from other transport protocols as they become available.
Because even TCP and UDP are not guaranteed to work in all environments
today, some programmers simply give up on using TCP or UDP directly,
relying instead on "HTTP as a Substrate". BCP 56 identified many issues
with this strategy, but assuming that if "any protocol is available on a
given network path and on the hosts that will be communicating, that
protocol will be HTTP" is a reasonable strategy for today's Internet.
The IESG has agreed with this viewpoint enough to publish the WebSocket
protocol on the standards track.
The goal of the TAPS working group is to help application and network
stack programmers by describing an (abstract) interface for applications
to make use of Transport Services. The Working Group deliverables
emphasize defining Transport Services that are important to applications
followed by experimental mechanisms to a) determine if the protocols to
provide the requested services are available on the end points and
supported along the path in the network and b) fall back, i.e., select
alternate, possibly less-preferred, protocols when desired protocols are
not available. The Working Group will not define a richer set of
Transport Services for applications, although the TAPS deliverables
could inform proposals for future chartered work on Transport Services.
The Working Group will:
1) Define a set of Transport Services, prioritizing those provided by
existing IETF protocols and congestion control mechanisms. As a starting
point, the working group will consider services used between two endpoints.
2) Specify the subset of those Transport Services, as identified in item
1, that end systems supporting TAPS will provide, and give guidance on
choosing among available mechanisms and protocols. Note that not all the
capabilities of IETF Transport protocols need to be exposed as Transport
Services.
3) Specify experimental support mechanisms to provide the Transport
Services identified in work item 2. This document will explain how to
select and engage an appropriate protocol and how to discover which
protocols are available for a given connection. Further, it will provide
a basis for incremental deployment. Work on this document will begin
when the TAPS Transport Services have been specified.
The following topics are out of scope for this Working Group:
- Signaling-based Quality-of-Service (QoS) mechanisms
- Definition of new encapsulations and tunneling mechanisms
- Extension, modification, or creation of transport protocols
- Language-specific APIs
TAPS is not chartered to perform detailed analysis of the security
aspects of transport protocols, but TAPS is being chartered almost
simultaneously with TCPINC, which is developing the TCP extensions to
provide unauthenticated encryption and integrity protection of TCP
streams, and TAPS will work with TCPINC to ensure that TAPS will be able
to accommodate the protocol extensions that TCPINC defines.
Milestones:
M9: Submit an Informational document to the IESG defining a set of
services provided by IETF transport protocols and congestion control
mechanisms.
M15: Submit an Informational document to the IESG recommending a minimal
set of Transport Services that end systems should support.
M18: Submit an Experimental document to the IESG specifying one or more
methods to provide applications with the Transport Services identified
by the WG.
M18: Recharter or close.
_______________________________________________
Taps mailing list
Taps@ietf.org
https://www.ietf.org/mailman/listinfo/taps
--
------------------------------------------
Dipl.-Ing. Mirja Kühlewind
Communication Systems Group
Institute TIK, ETH Zürich
Gloriastrasse 35, 8092 Zürich, Switzerland
Room ETZ G93
phone: +41 44 63 26932
email: mirja.kuehlew...@tik.ee.ethz.ch
------------------------------------------
_______________________________________________
Taps mailing list
Taps@ietf.org
https://www.ietf.org/mailman/listinfo/taps
