Re: [dtn-interest] more on the end-to-end principle

[Eric Travis <[e-mail]>]

Scott,

Great discussion.

I think we might be one step closer to mutual understanding (and hopefully
closure) of how to increase the general utility of the Bundle Protocol.

So while the ultimate responsibility for retransmitting data that are lost
> due to transmission failure assuredly remains with the source (the end),
> end-to-end retransmission may take so long that unacceptable delivery
> latency is introduced.  So we retransmit within the network to make
> performance acceptable.  We implement in the communication system an
> incomplete version of the function to enhance performance, while also
> providing simple mechanisms to support end-to-end retransmission at the
> application layer (at the ends).
>

As the failure mode of concern is corruption as data is locally copied
between bundle agent and convergence layer,  I would substitute "corrupted"
for "lost due to transmission failure", but the thought remains the same...

Given that the end-to-end path for a bundle is a sequence of one or more
*end-to-end* transfers between CL entities, and the bundle agents are the
"ends" of these transfers - might it not be prudent for to support
application layer retransmission (at the ends - bundle agent to bundle
agent) for these transfers too?

Regards,

Eric
[e-mail]



On Wed, May 7, 2014 at 12:44 PM, Burleigh, Scott C (312G) <
[e-mail]> wrote:

>  Hi, Patrick.  Without speculating on what might be the major unsolved
> problems in networking, I’ll comment briefly on the DTN protocols’
> alignment with the end-to-end principle.
>
> It has been occasionally asserted on this list that the design of the DTN
> protocols ignores the “end-to-end principle” that has served the Internet
> very well for several decades.  That erroneous assertion has been
> repeatedly refuted, without evident effect.  I’ll try one more time.
>
> On the contrary, the DTN design has borne the end-to-end argument in mind
> from the beginning and applies it literally, with considerable care.
> Salzer, Reed, and Clark, in “End-To-End Arguments In System Design” (ACM
> Transactions in Computer Systems 2(4), November 1984, pages 277-288), write:
>
> [Consider] …*a list of functions each of which might be implemented in
> any of several ways: by the communication subsystem, by its client, as a
> joint venture, or perhaps redundantly, each doing its own version. In
> reasoning about this choice, the requirements of the application provide
> the basis for a class of arguments, which go as follows:*
>
> *The function in question can completely and correctly be implemented only
> with the knowledge and help of the application standing at the end points
> of the communication system. Therefore, providing that questioned function
> as a feature of the communication system itself is not possible. (Sometimes
> an incomplete version of the function provided by the communication system
> may be useful as a performance enhancement.)*
>
> *We call this line of reasoning against low-level function implementation
> the "end-to-end argument."*
>
> In the case of delay-tolerant networking, there may never be
> contemporaneous end-to-end connectivity from the source to the
> destination.  So while the ultimate responsibility for retransmitting data
> that are lost due to transmission failure assuredly remains with the source
> (the end), end-to-end retransmission may take so long that unacceptable
> delivery latency is introduced.  So we retransmit within the network to
> make performance acceptable.  We implement in the communication system an
> incomplete version of the function to enhance performance, while also
> providing simple mechanisms to support end-to-end retransmission at the
> application layer (at the ends).
>
> Ultimate responsibility for protection of application data integrity
> likewise remains with the source and destination.  In DTN we provide a
> mechanism for end-to-end application data integrity protection, the Payload
> Integrity Block.  (One might argue that this mechanism is deficient, and
> that is certainly a valid topic for discussion.  But that claimed
> deficiency doesn’t demonstrate that the end-to-end principle was ignored.)
> But again, end-to-end application data integrity protection in DTN – while
> necessary – is not sufficient.  DTN communication links may be so limited
> in bandwidth that the propagation of corrupt or inauthentic data – e.g., a
> DOS attack – would have a significant impact on network performance, by
> wasting bandwidth needed for the transmission of authentic data; data
> integrity failures must be detected as early as possible so that corrupt
> data can be discarded immediately.   So again we implement within the
> communication system an incomplete version of the function to enhance
> performance: the hop-by-hop Bundle Authentication Block, for early
> detection of data corruption.
>
> Salzer, Reed, and Clark were themselves similarly pragmatic about
> application of the argument they had defined:
>
> *Frequently, the performance tradeoff is quite complex. Consider again the
> careful file transfer on an unreliable network. The usual technique for
> increasing packet reliability is some sort of per-packet error check with a
> retry protocol. This mechanism can be  implemented either in the
> communication subsystem or in the careful file transfer application. For
> example, the receiver in the careful file transfer can periodically compute
> the checksum of the portion of the file thus far received and transmit this
> back to the sender. The sender can then restart by retransmitting any
> portion that arrived in error.*
>
> *The end-to-end argument does not tell us where to put the early checks,
> since either layer can do this performance-enhancement job. Placing the
> early retry protocol in the file transfer application simplifies the
> communication system, but may increase overall cost, since the
> communication system is shared by other applications and each application
> must now provide its own reliability enhancement. Placing the early retry
> protocol in the  communication system may be more efficient, since it may
> be performed inside the network on a hop-by-hop basis, reducing the delay
> involved in correcting a failure. At the same time, there may be some
> application that finds the cost of the enhancement is not worth the result
> but it now has no choice in the matter. A great deal of information about
> system implementation is needed to make this choice intelligently.*
>
> The end-to-end argument was never intended to be dogma; it was intended to
> improve the engineering of networks.  The DTN architecture fully honors
> that intent, and always has.
>
> Scott
>
>
>
>
>
> *From:* dtn-interest [mailto:[e-mail]] *On Behalf Of
> *Gelard Patrick
> *Sent:* Wednesday, May 07, 2014 1:29 AM
> *To:* [e-mail]
> *Subject:* Re: [dtn-interest] DTN BoF Proposal for IETF90
>
>
>
> Dear all,
>
>
>
> >> Rediscovering the ramifications of the end-to-end principle cannot
> really be considered research at this point
>
> Is it a rediscovering of end-to-end principle variant or the need of new
> definition of end-to-end concept to take in account new Delay and
>  Disruption constraint ?
>
>
>
> Is that Delay-  and  Disruption-Tolerant  Networking can continue to be
> base on the principle of « Intelligence is at the end » : Network
> architecture must be as simple as possible – don’t bring in infrastructure
> specific optimizations for any particular purpose ? A "dumb" network with
> "smart" terminals ?
>
>
>
> Modern physic try to build « A theory of everything » to take in account
> major unsolved problems in physics<http://en.wikipedia.org/wiki/Unsolved_problems_in_physics>.
> What are the major unsolved problem in Networking ?
>
>
>
> Bests regard
>
> Patrick
>
> end-to-end principle http://en.wikipedia.org/wiki/End-to-end_principle
>
>
>
>
>
> *De :* dtn-interest [mailto:[e-mail]<[e-mail]>]
> *De la part de* [e-mail]
> *Envoyé :* mercredi 7 mai 2014 05:56
> *À :* [e-mail]; [e-mail]
> *Objet :* Re: [dtn-interest] DTN BoF Proposal for IETF90
>
>
>
> "Although DTN has clearly research issues to be addressed"
>
>
>
> I wouldn't describe these as research issues, but as basic engineering
> issues. Rediscovering the ramifications of the end-to-end principle cannot
> really be considered research at this point.
>
>
>
> "optimizing DTN for terrestrial or space environment only may cancel the
> original concept of interoperability of diverse environments."
>
>
>
> We have previously asked whether interoperability of diverse environments
> is warranted and worthwhile:
>
> Lloyd Wood, Peter Holliday, Daniel Floreani and Wesley M. Eddy,
>
> 'Sharing the dream: The consensual networking hallucination offered
>
> by the Bundle Protocol', peer-reviewed conference paper, Workshop on
>
> the Emergence of Delay-/Disruption-Tolerant Networks (E-DTN),
>
> part of the International Conference on Ultra Modern Telecommunication
>
> (ICUMT), St. Petersburg, Russia, 14 October 2009.  2 pages.
>
> http://dx.doi.org/10.1109/ICUMT.2009.5345655
>
>
> http://personal.ee.surrey.ac.uk/Personal/L.Wood/publications/index.html#e-dtn-position
>
> figure 1 is particularly helpful in thinking about this dichotomy of
> environments.
>
> Lloyd Wood
> http://about.me/lloydwood
>    ------------------------------
>
> *From:* dtn-interest <[e-mail]> on behalf of
> Vassilios Tsaoussidis <[e-mail]>
> *Sent:* Wednesday, 7 May 2014 11:47 AM
> *To:* [e-mail]
> *Subject:* Re: [dtn-interest] DTN BoF Proposal for IETF90
>
>
>
> I am also in favor of Fred's proposal. Although DTN has clearly research
> issues to be addressed, the level of maturity of BP along with the
> community's clear direction towards internet for everywhere, everything and
> everyone calls for IETF standardization actions. I am also in favor of
> forming a single group - to which I intend to participate; dichotomies
> typically cause more problems than they solve. Also, optimizing DTN for
> terrestrial or space environment only may cancel the original concept of
> interoperability of diverse environments.
>
>
>
> Vassilis Tsaoussidis
>
>
>
>
>
> Στις 2014-05-07 03:18, ccaini έγραψε:
>
> Dear Fred,
>
>       if the vitality of a research group is denoted by the number of mail
>
> exchanges on the group mailing list, I would say that your proposal has
>
> really brought new life to it!
>
> I am grateful for this.
>
> In my opinion, it was high time that somebody proposed to move DTN BP from
>
> pure research to engineering standardization also for non Interplanetary
>
> applications.
>
> I say this not because I think that BP is perfect and there is no need to
>
> further research, or just to include some of the features that at present
>
> are lacking in future RFCs (e.g. I am in favor of end-to-end CRC check,
>
> which is one of Wood's favorite arguments, with good reasons), but because
>
> without true applications in mind, without the active participation  of big
>
> companies, like Boeing, the DTN appealing outside of Interplanetary
>
> applications seems to me destined to slowly fade out.
>
> I suppose that the prospect of having a DTN standardized protocol
>
> supported by a big company can help in sustaining and rising the interest
>
> of Industry on DTN, which is essential to develop applications that are not
>
> just mere demos; applications that can show all the potential of the DTN
>
> concept and that can make the difference with present ones. This would also
>
> help in keeping alive and possibly reinvigorating DTN more open research
>
> too.
>
> Of course, IETF standardizations should be coordinated with CCSDS
>
> standardization for space applications, in order to maintain a unique DTN
>
> umbrella for both (i.e. some form of close interoperability).
>
>   Yours,
>
>     Carlo Caini
>
>
>
> (University of Bologna)
>
>
>
>
>
>
>
>
>
>
>
> On Tue, 6 May 2014 15:30:00 +0000, "Mehta, Devanshu - 0665 - MITLL"
>
> <[e-mail]> wrote:
>
>  In fact, a "blank sheet" dtnrg may reinvigorate some of the more silent
> members of the group. Devanshu ----- Original Message ----- From: Burleigh,
> Scott C (312G) [mailto:[e-mail]] Sent: Monday, May
> 05, 2014 08:00 PM Eastern Standard Time To: Marc Blanchet <
> [e-mail]> Cc: [e-mail] <
> [e-mail]> Subject: Re: [dtn-interest] DTN BoF Proposal for
> IETF90 Marc, certainly you are correct that taking both paths concurrently
>
> would
>
>  amount to twice as much work, more or less. But we are all individuals,
> all free agents (modulo the interests of our funding sources, for those
>
> of
>
>  us whose participation is funded). It's not as if there is a common
>
> pool
>
>  of people bandwidth that we can direct to work on one project or
>
> another:
>
>  those of us who are interested in one of these projects will work on it,
> and those who are not probably won't. I don't think excluding one of
>
> them
>
>  would much improve the effort that gets devoted to the other; rather, I
> think including both could accomplish more in total. Scott -----Original
> Message----- From: Marc Blanchet [mailto:[e-mail]] Sent:
> Monday, May 05, 2014 1:17 PM To: Burleigh, Scott C (312G) Cc:
> [e-mail] Subject: Re: [dtn-interest] DTN BoF Proposal for
> IETF90 Le 2014-05-05 à 12:52, Burleigh, Scott C (312G) <
> [e-mail]> a écrit :
>
> How about doing both? My understanding of Boeing's interest is that they
> are looking for standards to support fairly near-term commercialization of
> the RFC 5050-based technology that we've all gotten a good deal of
> experience with over the past few years. In that context, "fix 5050/BP"
> seems
>
> like
>
>  a good fit for the proposed working group. At the same time, taking up
> the last decade's worth of insight and knowledge and starting over again
> from a blank sheet of paper seems
>
>  like
>
>  exactly the right sort of thing for the DTN Research Group to take on.
>
> on "paper", I agree. But I have concerns on people bandwidth to work in
> two working groups. Even the current one has not met for quite some
>
> time.
>
>  So instead of starting 2, we may want to try to just (re-)start one...
> Marc.
>
> Scott -----Original Message----- From: dtn-interest [mailto:
> [e-mail]] On Behalf Of Kevin Fall Sent: Monday, May
> 05, 2014 12:03 PM To: Templin, Fred L Cc: [e-mail] Subject:
> Re: [dtn-interest] DTN BoF Proposal for IETF90 I can see a couple of ways
> you might go forward. If you start off as a "fix 5050/BP" you will
> encounter disagreement as to what are problems
>
> and
>
>  what are not. This is evident from the various exchanges over the
>
>  years.
>
>  Alternatively, you can start somewhat higher level with the notion that
> the area of challenged/DTN/DIL networks is to be addressed with a standard
> protocol (set), that there is now sufficient insight and knowledge thanks
> to DTNRG, and the field is open. There may be
>
>  different
>
>  design goals potentially (e.g., some web compatibility or whatnot)
>
>  which
>
>  was/were not a particular driving goal for DTNRG or BP. - Kevin On Mon,
> May 5, 2014 at 11:02 AM, Templin, Fred L <[e-mail]>
> wrote:
>
> Hi Lloyd, I have to say that I mostly agree with Stephen. IMHO, "Bundle of
> Problems" is a very useful document and still applies today, but I see it
> as an actionable problem statement and not an end-of-the-road
> pronouncement. I believe most of the BoP problems can be addressed in an
> RFC5050(bis) and we would tackle this in the initial working group
>
>  work
>
>   items. Thanks - Fred [e-mail]
>
> -----Original Message----- From: dtn-interest [mailto:
> [e-mail]] On Behalf Of [e-mail] Sent:
> Monday, May 05, 2014 12:13 AM To: [e-mail];
> [e-mail] Subject: Re: [dtn-interest] DTN BoF Proposal for
> IETF90 Stephen, I would discourage others from using or building on
> RFC5050, based on our experience in testing the Bundle Protocol in space
> [1], analysing the protocol's failings [2], and a variety of previously
> suggested fixes and drafts in this RG that never went anywhere, which
> aren't published. That's our engineering judgement on RFC5050 as it stands,
> and many long-time readers will be familiar with our arguments. But, as far
> as discussing the proposed WG and a modified RFC5050bis goes: Any protocol
> is simply an artefact that is an outcome of a process by people. It's
> reasonable to have doubts about the same pool of people producing anything
> better in a similar process. If there's a new crowd from Boeing et al with
> relevant expertise and funding/resources/time, that may help. (Or not,
> depending on the learning curve.) Will the putative IETF WG be as wholly
> focused on, say, security? I don't see how having a set of milestones
> magically fixes things that years in this research group, with discussion
> between the interested, did not. I don't see how an RG with failing output
> and limited adoption can be transformed into a WG with successful output
> and widespread (even terrestrial?) adoption, and I have never seen that
> done. (RGs have transformed and mutated into other RGs, with rather varying
> success.) How can a WG with the mandate 'fix the bundle protocol' succeed?
> Is it just being set up to fail? Should it therefore not be set up at all?
> [1] Will Ivancic, Wesley M. Eddy, Dave Stewart, Lloyd Wood, James Northam
> and Chris Jackson, 'Experience with delay-tolerant networking from orbit',
> peer-reviewed journal paper, International Journal of Satellite
> Communications and Networking, special issue for best papers of the Fourth
> Advanced Satellite Mobile Systems Conference (ASMS 2008), vol. 28, issues
> 5-6, pp. 335-351, September-December 2010.
> http://dx.doi.org/10.1002/sat.966
> http://personal.ee.surrey.ac.uk/Personal/L.Wood/publications/ijscn-a s
> ms-bundle-paper-submitted.pdf [2] Lloyd Wood, Wesley M. Eddy and Peter
> Holliday, 'A Bundle of Problems', peer-reviewed conference paper, IEEE
> Aerospace Conference, Big Sky, Montana, March 2009. 16 pages.
> http://dx.doi.org/10.1109/AERO.2009.4839384
> http://personal.ee.surrey.ac.uk/Personal/L.Wood/publications/wood-ie e
> e-aerospace-2009-bundle- problems.pdf Lloyd Wood
> http://sat-net.com/L.Wood/dtn that was a Star Wars reference, btw. May
> the 4th: may the force... ________________________________________ From:
> Stephen Farrell <[e-mail]> Sent: Monday, 5 May 2014 1:46
> AM To: Wood L Dr (Electronic Eng); [e-mail] Subject: Re:
> [dtn-interest] DTN BoF Proposal for IETF90 Lloyd, On 04/05/14 09:19,
> [e-mail]:
>
> I have a bad feeling about this.
>
> FWIW, my impression is that you'd have a bad feeling about anything
> related to rfc5050 regardless. IMO, it'd be quite reasonable for people to
> disregard quite a bit of what you say on that basis, i.e. that you appear
> to be interested in being destructively critical. That's a pity, since
> there are things to be improved/fixed for which you have argued, and with
> which others agree. Its even more a pity as it somewhat poisons the
> discussion, so I'd ask that if you can, please you try to put aside your
> distaste for rfc5050 and your annoyance at dtnrg history and try
> constructively discuss the proposed IETF wg. S.
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doubts, while the stupid ones are full of confidence.*

*
- Charles Bukowski*