Re: [tcmtf] Improved version of the tmctf Draft charter (v6)

[FERNANDO PASCUAL BLANCO <[e-mail]>]

Hi Jose,

        I like all your changes, they all enrich the WG description.

        Nevertheless I wanted to mention, after read carefully the text, that
when we talk about layers, we always use the three terms (tunneling,
multiplexing and compression) and I think it is ok.
        When we talk about the elements in charge of apply the TCMTF protocol we
have call them multiplexers and demultiplexers, and that may be a little
confusing, given that they use the name of the middle protocol layer, but
I understand that we have not found a better name (I include myself here)
and maybe multiplexing is the most representative layer, so it could be ok.
        But in paragraph 8 we talk about multiplexing flows and the impact of
multiplexing in protocol dynamics, and I think that may be confusing,
given that using "multiplexing" we are referring to apply the whole TCMTF
protocol or not and not only to apply the multiplexing layer or not. I´m
just saying that this term here may be confusing and someone could get a
bad interpretation from the text. I see three option: a) we pre-define the
term "multiplexing" as the application of the TCMTF protocol itself, b) we
invent the verb "to TCMTF" and use the participle "TCMTFed" when something
is passed trough our protocol stack or c) (and maybe the most convenient
we use the long form "the TCMTF protocol can be applied to that flow" or
"the impact of TCMTF protocol on protocol dynamics". My suggestion is to
use option c).

        What do you think?

        Thank you for your great effort!

Best,

Fernando Pascual Blanco
Telefónica Global Resources
Network Automation and Dynamization
TECHNOLOGY PEOPLE GROUP
F [phone]
M [phone]
[e-mail]




On 13/06/13 10:43, "Jose Saldana" <[e-mail]> wrote:

>These are the main changes included in the draft charter v6 (ordered by
>paragraphs):
>
>1. I have moved the sentence about the overhead to the end of the
>paragraph,
>in order to say that ³For both the delay-sensitive and delay-insensitive
>applications, their small data payloads incur significant overhead²
>
>2. I have put the scenarios in bullets, and I have improved some of the
>descriptions a bit.
>
>6. I have changed the name of the document: instead of ³document A² it is
>now ³TCMTF ­ reference model².
>
>7. Now we are talking about another document ³TCMTF ­ negotiation
>protocol².
>In addition, I have put the two signaling functionalities in bullets.
>
>7. As discussed in the list, we would talk about ³setup/release a TCMTF
>session².
>
>8. I have changed the name of the document, from ³document B² to ³TCMTF
>recommendations²
>
>8. According to Gorry¹s suggestion, I have added this sentence: ³The
>eventual impact of multiplexing on protocol dynamics (e.g. when
>multiplexing
>TCP flows) will also have to be addressed.²
>
>Jose
>
>
>> -----Mensaje original-----
>> De: [e-mail] [mailto:[e-mail]] En nombre de
>> Jose Saldana
>> Enviado el: jueves, 13 de junio de 2013 10:38
>> Para: [e-mail]; [e-mail]
>> Asunto: [tcmtf] Improved version of the tmctf Draft charter (v6)
>>
>> This is the new proposal, adapted to the new distribution of the
>documents.
>> I explain the changes in another e-mail.
>> It is also here, in a formatted version:
>> http://diec.unizar.es/~jsaldana/personal/ietf/tcmtf_charter_draft.pdf
>>
>>
>> TCMTF charter draft v6
>>
>> Description of Working Group
>>
>> 1. In the last years we are witnessing the raise of new real-time
>>services
>that
>> use the Internet for the delivery of interactive multimedia
>> applications: VoIP, 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. In addition, some
>> other services also send small packets, but they are not delay-sensitive
>(e.g.,
>> instant messaging, m2m packets sending collected data in sensor networks
>> using wireless or satellite scenarios). For both the delay-sensitive and
>delay-
>> insensitive applications, 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.
>>
>> 2. The efficiency cannot be increased by the inclusion of a higher
>>number
>of
>> samples in a single packet, since this would harm the delay requirements
>of
>> the service. But there exist some scenarios in which a number of flows
>share
>> the same path. In this case, packets belonging to different flows can be
>> grouped together, adding a small multiplexing delay as a counterpart of
>> bandwidth saving. This delay will have to be maintained under some
>> threshold in order to grant the delay requirements. Some examples of the
>> scenarios where grouping packets is possible are:
>>
>> - aggregation networks of a network operator;
>> - an end-to-end tunnel between appliances located in two different
>>offices
>> of the same company;
>> - the access connection of an Internet Café including a high number of
>> VoIP/gaming flows;
>> - an agreement between two network operators could allow them to
>> compress a number of flows they are exchanging between a pair of
>>Internet
>> Routers;
>> - a satellite connection used for collecting the data of a high number
>>of
>> sensors.
>>
>> 3. VoIP using RTP is a clear example of a real-time service using small
>packets
>> with high overhead. In order to improve efficiency, RFC4170 (TCRTP)
>defined
>> a method for grouping packets when a number of flows share a path,
>> considering three different layers: header compression by means of
>>ECRTP;
>> multiplexing by means of PPPMux; tunneling by means of L2TPv3.
>>
>> 4. However, in the last years, emerging real-time services which do not
>use
>> UDP/RTP have become popular: some of them use UDP or even TCP. In
>> addition, new header compression methods have been defined (ROHC). So
>> there is a need of widening the scope of RFC4170 in order to consider
>>not
>> only UDP/RTP but also other protocols. The same structure of three
>>layers
>> will be considered:
>>
>> - Header compression: Taking into account that real-time applications
>>use
>> different headers (RTP/UDP, UDP or even TCP), different protocols can be
>> used: no compression, ECRTP, IPHC and ROHC.
>> - Multiplexing: If a number of flows share a path between an origin and
>>a
>> destination, a multiplexer can build a bigger packet in which a number
>>of
>> payloads share a common header. A demultiplexer is then necessary at the
>> end of the common path, so as to rebuild the packets as they were
>originally
>> sent. PPPMux will be the main option. Other ones are not discarded.
>> - Tunneling will be used to send the multiplexed packets end-to-end. The
>> options in this layer are L2TP, GRE and MPLS.
>>
>> 5. So the first objective of this group is to specify the protocol stack
>for
>> tunneling, compressing and multiplexing traffic flows (TCMTF). Since
>> standard protocols are being used at each layer, the signaling methods
>>of
>> those protocols will be used. Interactions with the Working Groups and
>Areas
>> in which these protocols are developed can be expected. However, the
>> development of new compressing, multiplexing or tunneling protocols is
>>not
>> an objective of this Working Group. In addition, since the current RFC
>4170
>> would be considered as one of the options, this RFC could be obsoleted.
>>
>> 6. As a first objective, a document (TCMTF - reference model) will
>>define
>the
>> different options which can be used at each layer. Specific problems
>caused
>> by the interaction between layers will have to be issued, and suitable
>> extensions may have to be added to the involved protocols.
>>
>> 7. If a pair multiplexer/de-multiplexer want to establish a TCMTF
>>session,
>> they have first to use a mechanism to negotiate which concrete option
>would
>> they use in each layer: header compression, multiplexing and tunneling.
>This
>> will depend on the protocols that each extreme implements at each level,
>> and in the scenario. So another document (TCMTF - negotiation protocol)
>will
>> include:
>>
>> - a mechanism to setup/release a TCMTF session between a multiplexer and
>> a de-multiplexer, also including:
>> - a negotiation mechanism to decide the options to use at each layer
>(header
>> compression, multiplexing and tunneling) between multiplexer and de-
>> multiplexer,
>>
>> 8. As a counterpart of the bandwidth saving, TCMTF may add some delay
>>and
>> jitter. This is not a problem for the services which are not sensitive
>>to
>delay.
>> However, regarding delay-sensitive services, the Working Group will also
>> develop a document (TCMTF - recommendations) with useful
>> recommendations in order to decide which packet flows can or can not be
>> multiplexed and how. The document will present a list of available
>>traffic
>> classification methods which can be used for identification of the
>>service
>or
>> application to which a particular flow belongs, as well as
>>recommendations
>of
>> the maximum delay and jitter to be added depending of the identified
>> service or application. The eventual impact of multiplexing on protocol
>> dynamics (e.g., when multiplexing TCP flows) will also have to be
>addressed.
>>
>> 9. If other interesting features are identified, the group would
>re-charter and
>> include them, e.g., a mechanism for a multiplexer to discover a de-
>> multiplexer, and vice versa; a mechanism to select an optimal
>>multiplexer
>> and a de-multiplexer when there are more than one muxer/de-muxer for a
>> flow; dynamically applying TCMTF: a higher entity in charge of deciding
>when
>> and where, applying or not TCMTF, and what kind of TCMTF, and what
>> multiplexing period. Additional methods for estimating delay would also
>>be
>> required.
>>
>> 10. In addition, specific uses of TCMTF, such as in wireless and
>>satellite
>> scenarios, could be considered, and it will be studied whether
>modifications
>> or extensions are required on the protocol.
>>
>> 11. Interactions with other Working Groups can be expected, since TCMTF
>> uses already defined protocols for compression, multiplexing and
>>tunneling
>> (ROHC, PPPMux, MPLS, GRE, L2TP).
>>
>> Goals and Milestones
>>
>> Specification of TCMTF  reference model.
>>
>> Specification of TCMTF negotiation protocol.
>>
>> Specification of TCMTF recommendations of using existing traffic
>> classification methods, maximum delay and jitter to add, depending on
>>the
>> service.
>>
>>
>> Current version of Document (TCMTF - reference model):
>> https://datatracker.ietf.org/doc/draft-saldana-tsvwg-tcmtf/
>>
>> Current version of Document (TCMTF - recommendations):
>> http://datatracker.ietf.org/doc/draft-suznjevic-tsvwg-mtd-tcmtf/
>>
>>
>> Best regards,
>>
>> Jose
>>
>>
>> _______________________________________________
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>> https://www.ietf.org/mailman/listinfo/tcmtf
>
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