Re: [tcmtf] TCMTF-Feedback about a possible BoF in London

Tina TSOU <> Thu, 09 January 2014 00:50 UTC

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From: Tina TSOU <>
To: Jose Saldana <>
Thread-Topic: [tcmtf] TCMTF-Feedback about a possible BoF in London
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Date: Thu, 9 Jan 2014 00:49:41 +0000
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Cc: "" <>, Luigi Iannone <>, "Black, David" <>, "" <>, Martin Stiemerling <>
Subject: Re: [tcmtf] TCMTF-Feedback about a possible BoF in London
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Dear all,
I'm in favor of having a BoF in London, as the following problem statement seems valid and needs protocol work in IETF.
In addition to VoIP, in the last years we are witnessing the raise of new real-time services e.g. videoconferencing, telemedicine, video vigilance, online gaming, etc.

Due to the need of interactivity, many of these services use small packets (some tens of bytes), since they have to send frequent updates between the extremes of the communication. Their small data payloads incur significant overhead, and it becomes even higher when IPv6 is used, since the basic IPv6 header is twice the size of the IPv4 one.

In the moments or places where network capacity gets scarce, allocating more bandwidth is a possible solution, but it implies a recurring cost. However, the inclusion of a pair of boxes able to optimize the traffic (reducing bandwidth and packets per second) when/where required is a one-time investment. We can do these three things:

a) header compression algorithms (e.g. ROHC) can be used for reducing the overhead of each flow;
b) at the same time, tunneling can be used in order to allow the header-compressed packets to travel end-to-end
c) compressed packets belonging to different flows can be multiplexed together, in order to share the tunnel overhead.

These emerging real-time services which use bare UDP instead of UDP/RTP have become popular. In addition, a significant effort has been devoted to the deployment of new header compression methods with improved robustness (ROHC). So there is a need of widening the scope of RFC4170 in order to consider these new header compression methods, and also UDP in addition to UDP/RTP.

As a result, the next objectives can be achieved:

* Significant bandwidth reductions (as an example, bandwidth savings of 55% can be obtained for VoIP if IPv4 is used, and 65% using IPv6. For certain online games, 33% of the bandwidth can be saved for IPv4, and 55% when using IPv6).

* A reduction of the amount of packets per second managed by the network. A reduction factor of 10 or 20 can easily be achieved. This can be translated into smaller processing delays and energy savings in intermediate routers.

Thank you,

On Jan 8, 2014, at 4:11 PM, "Jose Saldana" <<>> wrote:

Hi all.

First of all, thanks to David and Luigi for their valuable comments.

I will wait for a while in order to include David’s comments (perhaps some other people has more suggestions).

These are the improvements of version 10 with respect to v9 (

- I have shortened paragraph 1.
- I have shortened and merged paragraphs 2 and 3.
- I have moved paragraph 4 to the third place, in order to set clearer what we want: replacing RFC4170 with a widened proposal. As David suggested, I have also shortened the text and it is now more straightforward.
- I have clearly stated which protocols will be used on each layer. The negotiation mechanism is still necessary, since different options are considered e.g. for header compression. The one to be used will depend on the scenario and the processing capacity of the two optimizers.
- I have significantly shortened the description of the scenarios.
- I have removed paragraph 6, which included the savings figures.
- I have included the replacement of RFC4170 in the first milestone.



De: Black, David []
Enviado el: sábado, 04 de enero de 2014 4:05
Para: Jose Saldana;<>;<>
CC: Martin Stiemerling; Black, David
Asunto: RE: TCMTF-Feedback about a possible BoF in London

A second BoF has the explicit goal of forming a WG, as a third BoF
is not permitted.  In that regard, the new charter seems long and
somewhat lacking in focus.  Two key things I look for in a proposed
charter are what problem (or problems) the proposed WG is looking to
solve and an initial approach to the problem or problems.

In the new draft charter, the problem statement appears to be in
paragraph 4 with paragraph 1 providing important background.  The
focus of the work appears to be on extending TCRTP (RFC 4170) to
UDP and to include new compression protocols.  In contrast, I have
a hard time discerning the initial approach from the new draft charter.

In light of this, there are a few things that I wish the new
draft charter had definitive proposals for:

      a) Whether to replace RFC 4170 vs. write a new RFC (could be
            UDP-only or UDP + RTP/UDP) as a complement to RFC 4170.
      b) Whether to use ECRTP, ROHCv2 (RFC 5225) and/or IPHC (RFC 2507 ?).
            Non-use of ECRTP would be a major change to 4170, and I
wonder about IPHC, as opposed to the ROHCv2 profiles.
      c) Analogies to b) for the Mux and Tunnel layers of the stack.

Overall, it looks like the first task of the WG is to select the protocol
stack to standardize - I have misgivings about that, and would prefer to
see a concrete proposal in a crisp charter that ran along the following
lines, naming the protocols to be used:

1) RFC 4170 does X, and needs the following changes/additions: X, Y, Z.
2) The WG will replace RFC 4170 with a new RFC that contains: A, B, C.

A specific proposal or proposals for the protocol stack or stacks
would also narrow the scope of item 9 in the charter on the negotiation
mechanism.  I also don’t see a goal/milestone listed for an extension to
or replacement for RFC 4170.

I’d prefer to see a much shorter more focused draft charter.  There’s a
bunch of background material that does not seem crucial to the charter,
starting w/paragraphs 2 and 3.


From: tsv-area [] On Behalf Of Jose Saldana
Sent: Friday, December 20, 2013 4:26 AM
Cc: Martin Stiemerling
Subject: TCMTF-Feedback about a possible BoF in London

Hi all,

After the feedback received in the BoF in Berlin, we have updated the TCM-TF charter and the two drafts. We have tried to solve all the problems raised during the session.

Our plan is to request a new BoF in London next March, so we would like to know your opinion about these two questions:

1.  Is the new, reduced scope of TCM-TF suitable to form a working group?

2. We would like to kindly ask people who think that a TCM-TF Working group should be formed, to come forward and send an e-mail to the<>  mailing list stating it.

This feedback will allow us to get a better idea of the convenience of a BoF.

The new charter is here:
This is the old one (presented in Berlin):

In these links you can see the differences between the new versions of the drafts and the old ones:

The main improvements are:

- TCP optimization has been removed
- The classification of the scenarios has been refined and improved. Some of them have been removed
- A section about energy consumption has been added to the main draft
- A reference to the potential problem of the MTU and packet loss has been added
- The problem of the added delays is studied in detail in the second draft

- The improvements of the charter are summarized here:

Best regards,