Re: Informational RFC to be: <draft-irtf-iccrg-welzl-congestion-control-open-research-08.txt>

The IESG <> Mon, 13 September 2010 22:46 UTC

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From: The IESG <>
Subject: Re: Informational RFC to be: <draft-irtf-iccrg-welzl-congestion-control-open-research-08.txt>
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The IESG has no problem with the publication of 'Open Research Issues in
Internet Congestion Control'
<draft-irtf-iccrg-welzl-congestion-control-open-research-08.txt> as an
Informational RFC.

The IESG would also like the IRSG to review the comments in
the datatracker
related to this document and determine whether or not they merit
incorporation into the document. Comments may exist in both the ballot
and the comment log.

A URL of this Internet Draft is:

The process for such documents is described at

Thank you,

The IESG Secretary

Technical Summary

   This document describes some of the open problems in Internet  
   congestion control that are known today. This includes several new  
   challenges that are becoming important as the network grows, as well  
   as some issues that have been known for many years. These challenges  
   are generally considered to be open research topics that may require  
   more study or application of innovative techniques before Internet- 
   scale solutions can be confidently engineered and deployed. 

Working Group Summary

   This document represents the work and the consensus of the ICCRG.


   Lars Eggert ( has reviewed this document for the IESG.

RFC Editor Note

(1) Replace beginning of Section 3.5.3 with:

  3.5.3 Inelastic Multi-domain Pseudowires

  Extending pseudo-wires across multiple domains poses specific issues.
  Pseudowires (PW) [RFC3985] may carry non-TCP data flows (e.g. TDM
  traffic or Constant Bit Rate (CBR) ATM traffic) over a multi-domain 
  IP network. Structure Agnostic TDM over Packet (SATOP) [RFC4553], 
  Circuit Emulation over Packet Switched Networks (CESoPSN), TDM over 
  IP, are not responsive to congestion control as discussed by
  [RFC2914] (see also [RFC5033]). The same observation applies to ATM 
  circuit emulating services (CES) interconnecting CBR equipment (e.g. 
  PBX) across a Packet Switched Network (PSN).

  Moreover, it is not possible to simply reduce the flow rate of a TDM
  PW or an ATM PW when facing packet loss. Providers can rate control 
  corresponding incoming traffic but they may not be able to detect 
  that PWs carry TDM or CBR ATM traffic (mechanisms for characterizing 
  the traffic temporal properties may not necessarily be supported). 

  This can be illustrated with the following example. 

(2) Add at the end of Section 3.8.4 Congestion Control in Multi-layered Networks

  Section 3.5.3 deals with Inelastic Multi-domain Pseudowires (PW), 
  where the characteristics of the Pseudowire itself determines the 
  characteristics of the traffic crossing the multi-domain PSN 
  (and this independently of the characteristics of the traffic 
  carried in the PW). A more complex situation arises when inelastic 
  traffic is carried as part of a Pseudowire (e.g. inelastic traffic 
  over Ethernet PW over PSN) whose edges do not have the means to 
  characterize the properties of the traffic encapsulated into the
  Ethernet frames. In this case, the problem explained in 
  Section 3.5.3 is not limited to multi-domain Pseudowires but more 
  generally induced by "Pseudowire carrying inelastic traffic" (over 
  a single- or multi-domain PSN). The problem becomes even more
  intricated when the Ethernet PW carries both inelastic and 
  elastic traffic. Addressing this issue further comforts our 
  observation that a general framework to efficiently deal with 
  congestion control problems in multi-layer networks is absolutely
  necessary but without harming its evolvability.