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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>An alert of the Congestion Exposure (CONEX) Bof in </span></font>Hiroshima
- currently scheduled for Tues 15.20 – 18.10. </p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Best wishes,</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Philip Eardley & Leslie Daigle (BoF Chairs)</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Congestion Exposure (CONEX)</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>(was re-ECN)</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Description</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Congestion Exposure (ConEx) is a proposed new IETF activity to enable
congestion to be exposed along the forwarding path of the Internet. By
revealing expected congestion in the IP header of every packet, congestion
exposure provides a generic network capability which allows greater freedom
over how capacity is shared. Such information could be used for many purposes,
including congestion policing, accountability and inter-domain SLAs. It may
also open new approaches to QoS and traffic engineering.</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>The Internet is, in essence, about pooling resources. The ability to
share capacity has been paramount to its success and has traditionally been
managed through the voluntary use of </span></font>TCP congestion control.
However, TCP alone is unable to prevent bandwidth intensive applications, such
as peer-to-peer or streaming video, from causing enough congestion to severely
limit the user-experience of many other end-hosts. This has led ISPs to deploy
ad-hoc solutions such as volume accounting, rate policing and deep packet
inspection in an attempt to distribute capacity differently. The consequences
of such practices are increasingly leading to calls for government regulations
and stifling innovation at the transport and application layer (see for
example, the problem statement I-D (ref below) and RFC5594).</p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>We believe these problems stem from the lack of a network-layer system
for accountability -- among all parties -- for sending traffic which causes
congestion. We propose a metric where IP packets carry information about the
expected rest-of-path congestion, so that any network node may estimate how
much congestion it is likely to cause by forwarding traffic. A network operator
can then count the volume of congestion about to be caused by an aggregate of
traffic as easily as it can count the volume of bytes entering its network
today. Once ISPs can see rest-of-path congestion, they can actively discourage
users from causing large volumes of congestion, discourage other networks from
allowing their users to cause congestion, and more meaningfully differentiate
between the qualities of services offered from potential connectivity partners.
Meanwhile end-hosts may be freed from rate restrictions where their traffic
causes little congestion.</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>The purpose of the BoF is to explore the support for and viability of
pursuing an IETF activity to define a basic protocol to expose the expected
rest-of-path congestion in the IP header. Any such protocol should work with
minimal changes to the existing network, in particular it should work with
unmodified routers. There is already one existing proposal that builds on ECN
to provide rest-of-path congestion information in every IP header and other
proposals may come forward.</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>If supported, an eventual WG would focus on the development of that
protocol as its main work item. Additional work items could include detailing
the motivations for congestion exposure, a threat analysis of the subsequent
protocol, providing feedback on experimental trials and describing deployment
considerations. Importantly, the proposed WG would encourage experimentation
but not deliberate on how congestion exposure should be used: our concern would
be how flexibly the resulting protocol can support differing needs at run-time,
rather than dictating a particular usage at design time.</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Related Internet-Drafts include: </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a
href="http://www.ietf.org/id/draft-moncaster-congestion-exposure-problem-01.txt">http://www.ietf.org/id/draft-moncaster-congestion-exposure-problem-01.txt</a>
</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="http://www.ietf.org/id/draft-briscoe-tsvwg-re-ecn-tcp-08.txt">http://www.ietf.org/id/draft-briscoe-tsvwg-re-ecn-tcp-08.txt</a>
</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a
href="http://www.ietf.org/id/draft-briscoe-tsvwg-re-ecn-tcp-motivation-01.txt">http://www.ietf.org/id/draft-briscoe-tsvwg-re-ecn-tcp-motivation-01.txt</a>
</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Other useful reference material: </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="http://www.bobbriscoe.net/projects/refb/FairerFasterWP.pdf">http://www.bobbriscoe.net/projects/refb/FairerFasterWP.pdf</a>
</span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Mailing list for discussion: </span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><a href="mailto:re-ecn@ietf.org">re-ecn@ietf.org</a> </span></font></p>
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