Re: [dtn] working group last call on draft-ietf-dtn-bpbis
Stephen Farrell <stephen.farrell@cs.tcd.ie> Mon, 27 March 2017 21:23 UTC
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To: "Burleigh, Scott C (312B)" <scott.c.burleigh@jpl.nasa.gov>, Marc Blanchet <marc.blanchet@viagenie.ca>, dtn <dtn@ietf.org>
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From: Stephen Farrell <stephen.farrell@cs.tcd.ie>
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Subject: Re: [dtn] working group last call on draft-ietf-dtn-bpbis
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On 27/03/17 22:21, Burleigh, Scott C (312B) wrote: > Fair enough. I am happy to leave this up to the wisdom of the WG. As will I, after we've considered the examples given in the review (which we have yet to do). I don't think it'd be a good plan at all for the WG to conclude that all the prescriptive text is ok without considering at least the issues raised as examples. S. > > Scott > > -----Original Message----- > From: Stephen Farrell [mailto:stephen.farrell@cs.tcd.ie] > Sent: Monday, March 27, 2017 2:19 PM > To: Burleigh, Scott C (312B) <scott.c.burleigh@jpl.nasa.gov>; Marc Blanchet <marc.blanchet@viagenie.ca>; dtn <dtn@ietf.org> > Subject: Re: [dtn] working group last call on draft-ietf-dtn-bpbis > > > > On 27/03/17 22:15, Burleigh, Scott C (312B) wrote: >> Okay, if you believe that it is unnecessary to be able to test for the >> correct operation of a BP agent -- that is, an implementation of an >> Internet standards-track RFC -- then I think we may be at the root of >> the issue. Let's continue tomorrow. > > Sure. To clarify though: I don't believe one needs to be able to verify a fully correct implementation of the BP purely from outside the box. Mail MTAs for example don't have that property and I think email RFCs are fairly good standards. > > Cheers, > S. > >> >> Scott >> >> -----Original Message----- From: Stephen Farrell >> [mailto:stephen.farrell@cs.tcd.ie] Sent: Monday, March 27, 2017 1:37 >> PM To: Burleigh, Scott C (312B) <scott.c.burleigh@jpl.nasa.gov>; Marc >> Blanchet <marc.blanchet@viagenie.ca>; dtn <dtn@ietf.org> Subject: Re: >> [dtn] working group last call on draft-ietf-dtn-bpbis >> >> >> Hi Scott, >> >> On 27/03/17 21:27, Burleigh, Scott C (312B) wrote: >>> Hi, Stephen. I won't try to respond to all these points now, but I >>> do want to advance a little bit of an argument on your point (B). >>> >>> If we look at, say, RFC 5681, I think we see a great deal of firmly >>> prescriptive text that has nothing to do with what bits are >>> transmitted over the wire, and everything to do with how the TCP >>> state machine is supposed to behave. >> >> But 5681 is based on some decades of really widespread deployment. If >> the BP were in that position I think you'd have a good argument there, >> but it isn't. >> >>> I think this is true of virtually every MUST in the specification, >>> and I think that in the absence of this prescriptive language it >>> would be impossible to distinguish a correctly functioning router >>> from a broken one -- impossible to test a router for correct >>> operation. >> >> I don't believe that an ability to test such correctness from outside >> a router is really necessary nor desirable at this point in the >> evolution of the BP. >> >>> I think the prescriptive language in the BPbis specification is just >>> as necessary, for exactly the same reasons. >>> >>> I understand that you disagree, but I don't yet understand why. >> >> I guess I'll point at the examples I offered as to why. I look forward >> to seeing your (or others') responses to those examples. >> >> I do hope we agree that egregious/unnecessary MUST statements are a >> bad idea though. If so, the question becomes whether or not all these >> many MUSTs are needed or not. >> >> Cheers, S. >> >>> >>> Scott >>> >>> -----Original Message----- From: Stephen Farrell >>> [mailto:stephen.farrell@cs.tcd.ie] Sent: Monday, March 20, 2017 >>> 3:06 PM To: Burleigh, Scott C (312B) >>> <scott.c.burleigh@jpl.nasa.gov>; Marc Blanchet >>> <marc.blanchet@viagenie.ca>; dtn <dtn@ietf.org> Subject: Re: [dtn] >>> working group last call on draft-ietf-dtn-bpbis >>> >>> >>> Hi Scott, >>> >>> Belated responses below. I hope the quoting isn't too messed up to >>> follow. >>> >>> As a TL;DR, I'd say we might be best to debate point (B) below, that >>> the current text is overly prescriptive. I'm entirely happy that the >>> DoS-vector that would be the current reporting text won't make it to >>> the RFC, so am ok if we don't spend so much time on that. >>> >>> For the "too prescriptive" point, I think you and I Scott have had >>> that debate before, so I'd be most interested in other WG >>> participants telling me I'm just wrong that all those MUSTs are >>> needed for interop. (I mean using some of the examples below that >>> refer back to point (B) and not literally a sentence that means the >>> same as the sentence before this one:-) >>> >>> Cheers, S. >>> >>> On 15/03/17 17:00, Burleigh, Scott C (312B) wrote: >>>> Hi. As Rick suggested, I'm posting my thoughts on Stephen's >>>> comments to the list in addition to noting them on Ed's spreadsheet >>>> - mainly transcribing them but amplifying in a few instances. >>>> In-line below. >>>> >>>> Scott >>>> >>>> -----Original Message----- From: dtn [mailto:dtn-bounces@ietf.org] >>>> On Behalf Of Stephen Farrell Sent: >>>> Monday, January 23, 2017 7:33 PM To: Marc Blanchet >>>> <marc.blanchet@viagenie.ca>; dtn <dtn@ietf.org> Subject: Re: >>>> [dtn] working group last call on draft-ietf-dtn-bpbis >>>> >>>> >>>> Hiya, >>>> >>>> I've done a review of bpbis-06 and have many comments. (Sorry:-) >>>> >>>> Overall I don't think this is ready, and some more discussion of >>>> some of the issues is needed. Since I've not followed the list as >>>> closely as I'd have liked I may have missed some such discussion in >>>> which case pointing me at the relevant bit(s) of the archive would >>>> be a fine response. >>>> >>>> I've tried to separate stuff into things that'd cause me to ballot >>>> DISCUSS in IESG evaluation (*), things that might not, and nitty >>>> things. I hope that helps, but don't take that categorisation too >>>> seriously:-) >>>> >>>> Cheers, S. >>>> >>>> (*) Note that I'll likely not still be on the IESG when this gets >>>> there (I escape in March) so the fact that I would ballot DISCUSS is >>>> not that relevant to what other ADs might do. >>>> >>>> >>>> Possibly major issues (DISCUSS like) >>>> ------------------------------------ >>>> >>>> (A) intro: The last bullet list of the things that are not specified >>>> here seems problematic for a PS and I think needs more >>>> discussion/work. I'm not sure if it's only the text that needs work, >>>> or if the missing specification is required now. Taking the bullets >>>> one at at time (numbers are in order of presentation): 1) This isn't >>>> clear enough, I'm not sure what's being omitted, 2) Omitting routing >>>> I think is fair, 3) It's also fair to omot RIB/FIB issues, 4) it's >>>> not ok to omit security mechanism definition, (making [BPSEC] >>>> normative and waiting on that in the RFC editor queue would fix >>>> this, and is IMO needed), 5) I'm not sure what's right here. I >>>> think it'd be good to have some list discussion about this, as it'll >>>> certainly come up in IETF LC and IESG review and having list traffic >>>> at which to point will help backup whatever conclusions are reached. >>>> In particular in 4.3, I don't think it's acceptable for the BIB and >>>> BCB to not have a normative reference. Similarly, the "TBD" for the >>>> other extension block types are not appropritate. (But those can >>>> likely be informative refs.) >>>> >>>> - I'm fine with bringing bpsec along at the same time as bp(bis) >>>> and tcpcl. >>> >>> Cool. I think that's the right choice. >>> >>>> >>>> (B) The spec is overly prescriptive in many places and ought be >>>> loosened up wherever possible. All we need is interop and not the >>>> kind of conformance at which this spec seems to aim (but maybe >>>> miss). For exmple the "retention constraint" stuff has absoluely no >>>> reason to be a MUST. As another, I think section 5.4 only needs a >>>> MUST in step 4 and all the rest are bogus and a bad plan. >>>> Also in 3.1, the text here is often far too prescritpive and I >>>> suspect based on only a couple of implementation strategies. >>>> There are many more examples. I think it'd be a good plan to do an >>>> editing pass to get rid of as many of the extraneous and unnecessary >>>> constraints that are here. Examples feature in other comments, but >>>> I've not tried to be exhaustive in spotting all instances of this. >>>> >>>> - I disagree. In general, I think this language needs to be >>>> normative in order to ensure coherent behavior among nodes of the >>>> network. >>> >>> Yep, I figured we'd not see eye to eye on the broader conformance >>> issue, in the same way that we've disagreed about that for about a >>> decade now:-) >>> >>> Nonetheless, I will continue to argue the point, and I note that you >>> didn't respond to the examples in the above. Those are only examples, >>> but I think some discussion of them may help us to see that the >>> current text is (or is not) overly prescriptive. >>> >>>> >>>> (C) Many of the flags relaed to reporting provide ways in which the >>>> BP, if it became widely deployed (even if not planned to be widely >>>> used), could be a significant (D)DoS accelerator. Has anyone figured >>>> out the scale factors involved, (e.g. if N bogus blocks say report >>>> if this can't be processed) whether those might be significant and >>>> if so what potential countermeasures might apply? Absent such an >>>> analysis, or fixing the problem, I'd argue it'd seem irresponsible >>>> to standardise the BP. I'd say for a PS, the minimum is that BPAs >>>> MUST default to not sending all these new bundles except when >>>> specifically configured to be so verbose. >>>> This also affects 5.1 and maybe elsewhere which says an agent MUST >>>> emit admin bundles if asked. In 5.6, step 2: again the SHOULD needs >>>> to be qualified in order to not have the BP be a fine DoS >>>> accelerator (given non-singletons). Step 3's SHOULD for this is even >>>> worse as a bad actor could include many such blocks. >>>> In 5.13 - I think that is too many custody signals. If one envisages >>>> DTNs with custodians located at links that are particularly subject >>>> to disruption, then those may be few in number and having all other >>>> nodes/routers emit custody signals for each bundle not taken into >>>> custody seems hugely inefficient and unnecessary. There may be more >>>> examples. FWIW, my guess is that if all the current reporting is >>>> kept, then the IESG will require some kind of applicability >>>> statement about the kind of network in which the BP can safely be >>>> deployed. For me, fixing the problem is a better approach than >>>> constraining it via an applicability statement. >>>> >>>> - I agree with making all status report generation "SHOULD" >>>> rather than "MUST". But if it is possible to generate status >>>> reports (and I think it has to be, for network troubleshooting >>>> purposes) then it is always possible for a badly engineered >>>> implementation to generate them more frequently than might be >>>> optimal in a given network. I'm unclear on how we can legislate >>>> against that. Strong language warning the implementer of the >>>> possible dangers would be fine with me; is that enough? >>>> Something like "Implementations MUST limit the generation of status >>>> reports so as to prevent excessive network traffic. >>>> Strategies for limiting status report generation are beyond the >>>> scope of this specification." >>> >>> I think that a SHOULD for emitting these is just wrong for the >>> Internet. If 10^8 BPAs were deployed (there are maybe that many web >>> sites) and each by default will emit these reports then that'd be >>> just crazy as they could be per-hop and could bounce around all over >>> the place. At that scale there'd also no doubt be reports generating >>> reports (due to gatewaying even if that was disallowed in the BP) and >>> one would get explosions of reports. I think the only defensible >>> position is for *all* of these to be specified as "MUST be off by >>> default" to be acceptable for a proposed standard. >>> >>> I would be ok if someone wanted to try characterise the kind of DTN >>> or node(s) in which it'd be ok to have these turned on. That could of >>> course be done in a separate document later. (Or outside the IETF if >>> it was e.g. really better a CCSDS thing.) >>> >>>> >>>> A bit less major (maybe not DISCUSS-worthy) >>>> ------------------------------------------- >>>> >>>> (1) 3.1's definition of a bundle correctly says that bundles are >>>> better when they include all the meta-data that might be useful. >>>> If considered naively, that conflicts with modern approaches to >>>> privacy where we want to ensure that meta-data is only seen by those >>>> (nodes) that need to see meta-data, as one form of data >>>> minimisation. OTOH, one could argue that such bundles will ensure >>>> that meta-data and payloads enjoy the same security services, which >>>> is a good thing. In any case, I think it'd be useful to have a >>>> discussion about the privacy aspects of the BP, esp the ways in >>>> which those may be different from other protocols. For example, >>>> would we expect report-to URIs to commonly allow re-identification >>>> of a person? I don't recall we've ever really discussed such issues. >>>> >>>> - I think having that discussion would be fine. I don't think >>>> that discussion has to happen in this specification, nor that it has >>>> to happen before this specification is published. >>> >>> Disagree. I think now is exactly the right time to do a privacy >>> analysis. Later will be too late, if the protocol gets deployed at >>> scale. Note that I'm not arguing that the result has to be a BP with >>> fully understood and perfect privacy features. >>> >>>> >>>> (2) 3.1, destination: I think this ought be clear that delivery to >>>> some node in the endpoint represents success, i.e. that the BP does >>>> not force successful delivery to all or failure as a binary choice. >>>> >>>> - The spec doesn't define "success" at all, and I don't know why >>>> it would need to. >>> >>> Sure, but I was more asking for clarity - I didn't find it to be that >>> well explained what kind of effort(s) are expected with endpoints >>> containing >1 node. >>> >>>> >>>> (3) What bad things would follow if 3.2 was deleted? It may be that >>>> I'm too familiar with DTN (and hence not a good judge if this >>>> section is useful or not) but I didn't find it useful. Also >>>> - is 3.2 normative? If not, I'm even happier to see it go. If it is, >>>> then I gotta wonder if it conflicts with other text later. >>>> And I see there are a few 2119 MUSTs in there so I guess you do mean >>>> it to be normative or did they sneak in in by accident whilst >>>> editing? (As can happen.) If not deleting this section, I'd argue to >>>> find all the bits of text in it that are needed and move them all >>>> elsewhere and then delete the section. >>>> >>>> - I think 3.2 is essential to the specification. I'm fine with >>>> moving the 2119 language to another section, if that helps. >>> >>> Again, I don't think we'll agree here, as with point (B) above:-) >>> >>> I note that you've not given an argument for including 3.2 though >>> other than stating that it's essential, and I did ask what'd be lost >>> if it were deleted so that seems not highly responsive. >>> >>>> >>>> (4) 3.2: The idea that the EID fully determines the MRG seems just >>>> wrong to me. While that might be a nice theory, I figure it's way >>>> more likely that the routing scheme determines how many copies of a >>>> bundle are rx'd at how many instances of the destination EID. What'd >>>> be bad about losing that concept and letting (the determinants of) >>>> the MRG be unspecified here? >>>> >>>> - I think that would make the behavior of nodes so indeterminate >>>> that it can't be tested. >>> >>> I don't get that. Given that we're not defining routing here, aren't >>> we in that position already? We can't for example tell if a node >>> emitting 10 copies of a bundle at different times, to different next >>> hops, on different interfaces etc. is good or bad or not. >>> >>>> >>>> (5) 3.2, "Custody of a bundle MAY be taken only if the destination >>>> of the bundle is a singleton endpoint." That's plain wrong. Not all >>>> custodians can know about the desitnation being a singleton or not. >>>> And before you say it, I don't believe in the flag in 4.1.3 that >>>> allows an origin to specify this - I've never seen a real example of >>>> when that's useful - the only nearby case I recall was where the >>>> developer (me:-) knew we wanted distibution to all nodes in a >>>> multi-member endpoint but with best effort in terms of getting to >>>> them all and with custody and less frequent application layer >>>> re-tx's to ensure we got to as many as possible. This also affects >>>> 5.2. >>>> >>>> - "Singleton" doesn't say how many nodes are in the endpoint. It >>>> says what the maximum number of nodes in the endpoint is. The >>>> source node should know this. >>> >>> Huh? How can a source know that in general? I maintain my >>> position:-) >>> >>>> >>>> (6) 3.3, I'm not sure this is useful either. What'd break if it were >>>> deleted? (But then I never liked those bits of DTNRG's work >>>> either;-) >>>> >>>> - Sure, don't care. >>> >>> (I'll skip over stuff where there's little or nothing more to say, >>> like this one:-) >>> >>>> >>>> (7) Including some examples and an RFC 7942 implementation status >>>> section would be a good thing, if easily done. That would help >>>> progression and increase confidence in the correctness of the spec. >>>> >>>> - I don't think this is really necessary, but I don't mind >>>> adding an implementation status section. >>>> >>>> (8) 4.1.6: Was sub-second timing discussed by the WG? I'm not >>>> terribly pushed on that myself, but it'd be a shame to do an interop >>>> breaking change in the BP without discussing that topic. >>>> A reason to think about this is that there may be inter-VM (or >>>> intra-data-centre) reasons to consider the BP with sub-second timing >>>> as interesting. It'd be a shame to make that impossible just to make >>>> it slightly simpler to represent time. >>>> >>>> - It was discussed by the WG, and I believe we concluded that >>>> sub-second time representation wasn't needed here. >>> >>> That makes me a bit sad. If anyone else would like sub-second timing >>> maybe now'd not be too late if we ask nicely? >>> >>>> >>>> (9) 4.2.2, creation time rules: I don't see why it'd be a problem if >>>> node-id=X, creation-time=0,counter=0,lifetime=2s is used in two >>>> bundles emitted 3 seconds apart. Why does that justify a MUST NOT in >>>> the spec? >>>> >>>> - I agree with Ed on this. There may be purposes for which a >>>> log of bundles may be needed; that's impossible if bundles are not >>>> uniquely identified. >>> >>> (I'm not sure I saw Ed's argument, I guess it was not on the list, >>> sorry if I missed it.) >>> >>> I'd be a bit concerned that the MUST NOT is too hard to nodes without >>> good clocks and will just be ignored across reboots. If other code >>> elsewhere (e.g. log analysis) depended on a fiction from here that'd >>> not be great. >>> >>>> >>>> (10) 4.2.2: The "30 seconds" rule also seems wrong to me, as is the >>>> "MUST NEVER" (not a 2119 term btw) for re-use of the seq no, which >>>> is unrealistic. As an example of that last: what do you expect to >>>> happen with a node that usually knows the wall clock time, but, at >>>> this moment, knows that it does not? E.g. previous logs have some >>>> real dates, but current clock is 1970-01-01 or whatever. I think >>>> this is fixable but the current language is too prescriptive. Best >>>> might be to weaken the language here and to see what implementations >>>> do in the real world. >>>> >>>> - Sure. >>>> >>>> (11) 4.3.1: Is the SHALL here right? I would have thought a SHOULD >>>> is better to allow for legacy interop with 5050 via gateways, in >>>> which case there may be no node ID. That might be better off handled >>>> in some generic fashion though, and not piecemeal with each mention >>>> of node ID. >>>> >>>> - There are node IDs in 5050 also, >>> >>> Well, sorta but not really. IIRC implementations and deployments >>> mostly did include the moral-equivalent but didn't have to. >>> >>>> they're just not called by that term. I think SHALL is correct >>>> here. >>> >>> But fair enough, if nobody else cared, I'd fold on this one. >>> >>>> >>>> (12) 4.3.2: I don't believe it is correct to drop a bundle due to >>>> the lack of a previous node block, which is what sems to be implied >>>> here. Not all routing schemes need this and so it ought not be a >>>> MUST. Maybe a SHOULD is enough, but even if you say "MUST insert >>>> this" then I would like to argue that "receivers can decide to not >>>> care" be stated explicitly e.g. by saying that bundles MUST NOT be >>>> rejected solely due to the lack of this EB. >>>> >>>> - I think this will be a source of headaches eventually, but >>>> sure, we can relax this. >>>> >>>> (13) I'm not sure if you have all the right "watch out for the null >>>> EID node ID" text needed. (I didn't go back over everything, but >>>> it'd seem wrong e.g. in an current custodian AR. >>>> >>>> - I don't think there's an issue here, but sure, let's re-read >>>> with this in mind. >>>> >>>> (14) 5.4: "The bundle protocol agent MUST determine which node(s) to >>>> forward the bundle to." That's ungrammatical and close to BS - what >>>> if I want to multicast or broadcast the bundle or use some other >>>> opportunistic CLA? Or a sneakernet where nobody knows who'll be next >>>> hop. >>>> >>>> - Of course the BPA must determine which node(s) to forward the >>>> bundle to. What else is going to make that determination? >>>> Nothing in the spec says it has to make that determination right >>>> now; maybe it sets the bundle aside for a while until a data mule >>>> comes along - and then it determines that this data mule is one of >>>> the nodes to forward the bundle to. The text is correct. >>> >>> Disagree. A BPA might decide to send the bundle on an interface >>> that's broadcast in nature and not care who turns out to be the next >>> hop that e.g. accepts custody. I think the text reflects a quite >>> narrow conception of a CLA. >>> >>>> >>>> (15) 5.4: The text about the flow label should be deleted as it says >>>> nothing. If includng this, then the flow label spec may need to be a >>>> normative ref (arguably). >>>> >>>> - Okay. >>>> >>>> (16) 5.4 - I think this is badly misleading. There will be many >>>> cases where a bundle cannot be forwarded now but may be forwarded >>>> later. Am I wrong in reading this section as precluding that? >>>> >>>> - You are wrong in reading this section as precluding deferred >>>> transmission. >>> >>> Maybe it needs rewording then. (Happy to look over it with you >>> later.) >>> >>>> >>>> (17) 5.6, step 4 says one MUST handle "custody transfer redundancy" >>>> but that term seems undefined. >>>> >>>> - Sure, let's add a clause saying "this condition is termed >>>> 'custody transfer redundancy'". >>>> >>>> (18) 5.6 (step 5) points back to 5.3 which points to 5.7 or 5.4. >>>> I don't think such GOTOs are a good idea really. I suggest removing >>>> lots of this and adding in some informative (i.e. >>>> non-normative) pseudo code (or real code) as an appendix. >>>> >>>> - I disagree. >>> >>> See point (B) above I guess:-) >>> >>>> >>>> (19) I think some rules related to custody and fragmentation may be >>>> missing. For example, if bundle A is multicast and reaches two nodes >>>> on different paths who take custody (custodians C1/C2) and who both >>>> fragment but differently (into F11/F12 and F21/F22 resp) with >>>> eventually a custody ack for F21 reaching C1. Assume F21 is longer >>>> than F11, what is C1 to do with F11 when a custody timer expires? >>>> Ought it re-transmit or consider that the custody ack for F21 >>>> matched F11 sufficiently well? I'm not sure what'd be right here, >>>> if such cases can happen. I'd be fine with the spec admitting that >>>> some such corner cases exist, or maybe it's easy enough to figure >>>> out, not sure. >>>> >>>> - I don't think there is a problem. Custody transfer is >>>> undefined if the destination endpoint is not singleton. >>> >>> I wasn't referring to the destination here, C1/C2 are just routers on >>> paths to that destination. So I do think there's a problem, sorry. >>> >>>> >>>> (20) 5.10.1, I've always wondered why custody timer expiry is >>>> covered here, and not really considered a part of DTN routing. It >>>> seems to me to make more sense to couple custody timing and routing. >>>> If that resonated with folks, I think the change would be to make >>>> the timer-related text here into an illustrative example and to say >>>> that such things are better considered together with routing and/or >>>> by chunks of code that are somewhat more topology/disruption-aware >>>> of the situation in the particular DTN. >>>> >>>> - Custodial retransmission really has nothing to do with >>>> routing. >>> >>> I guess we disagree again there. I'd say with almost all routing >>> schemes (CGR and similar being an exception) figuring out the best >>> way to handle these timers will be intimately related to routing. >>> See also point (B) above:-) >>> >>>> >>>> (21) section 9 seems woefully incomplete - why is it ok to say "will >>>> be required" at WGLC? Surely the WG should at least have discussed >>>> the set of registries needed and the registration rules for those? >>>> E.g. do we sill want CCSDS to be able to add entries to some of >>>> those registries as we did with 5050? And has the WG considered how >>>> do all the things in this draft relate to the set of IANA registries >>>> related to the BP? [1,2] (In the case of [3], section 4.1.5.1 really >>>> probably does need to say something.) >>>> >>>> - Sure, let's review what other registries are needed here. >>>> >>>> [1] https://www.iana.org/assignments/bundle/bundle.xhtml [2] >>>> https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml#uri-s >>>> c >>>> >>>> > h >>>> >>>> >> emes-1 >>>> >>>> Seemingly more minor or nitty things >>>> ------------------------------------ >>>> >>>> - abstract: "This Internet Draft" is no longer appropriate language. >>>> >>>> - Sure. >>>> >>>> - abstract: I think this ought capture the fact that this version is >>>> not interoperable with 5050. That's not a bad thing, but worth >>>> noting here. >>>> >>>> - Worth saying, but not in the Abstract. >>>> >>>> - intro: I don't think the "sales" language is needed or appropriate >>>> in the first couple of paras. It should be entirely ok to say "we've >>>> learned stuff and fixed stuff." >>>> >>>> - Sure, whatever. >>>> >>>> - intro: "Custodial forwarding" is too terse at this point but also >>>> hard to explain briefly, is really a mechanism and not a >>>> capabililty, and maybe not such a highlight, so I'd delete that >>>> bullet >>>> >>>> - I disagree. Let's turn it into a sentence and keep it. >>>> >>>> - intro: "[TUT]" is quite outdated and using dtnrg.org for the >>>> reference isn't wise (particularly at the moment when we're seeing >>>> SERVFAIL from the relevant NS;-) >>>> >>>> - Sure. >>>> >>>> - intro: this is a bit self-serving, but maybe a reference to the >>>> architectural retrospective [3] that Kevin and I wrote might be >>>> useful here, though I've not checked if it touches on enough of the >>>> issues behind the differences between 5050 and this. >>>> >>>> - I don't think this is needed. >>>> >>>> [3] https://ieeexplore.ieee.org/document/4530739 >>>> >>>> - Figure 1: I wonder if it'd be worth pointing out that the BP does >>>> not have to run over a layer 4 that runs over a layer 3 etc. >>>> The figure and this text does give that impression that a "proper" >>>> transport is needed, which isn't the case. (Tactically, I'm not sure >>>> if the text as-is, or something more correct, would make getting a >>>> new RFC easier or harder - I guess it'll depend on the reader;-) >>>> >>>> - No, the spec already says "BP uses underlying "native" >>>> transport and/or network protocols". >>>> >>>> - Figure 2: Few if any of the applications I've used with the BP had >>>> an administrative element. That's maybe down to the experimental >>>> nature of the work we've done but I don't think it's correct to >>>> imply that all applications using the BP need to be able to handle >>>> admin records, if that's what you're implying. >>>> (I'm not sure.) I'd say indicating that that's an optional thing >>>> would be right. >>>> >>>> - I disagree. The application agent -- not the application -- >>>> is the thing that has an administrative element. We could say that >>>> a given BPA's application agent might lack an administrative >>>> element, in which case the node could not take custody of a bundle. >>>> I don't see much advantage in that, but I don't mind saying it. >>>> >>>> - 3.1, singleton: not sure if it's clear enough that all endpoints >>>> are sets, so this may puzzle folks. Maybe add e.g. >>>> "remember that endpoints are sets," not sure. >>>> >>>> - Let's assume that people reading this specification are able to >>>> read. >>>> >>>> - 3.1, forwarding: the text is odd - "sustained effort" is not >>>> mandatory, and what "that node" is meant here? >>>> >>>> - Nothing says how long "sustained" is, but okay, we could >>>> delete the word. But I have no idea how to make this sentence any >>>> clearer. There is exactly one possible antecedent for "that node". >>>> >>>> - 4: The first two SHALL statements are odd in that there's no way >>>> in which one could implement this spec and not conform to those I >>>> think. In cases like that it's fine to avoid 2119 language. Not a >>>> big deal though, as the current IESG don't get anal about that, >>>> though some ADs in the past have done;-) >>>> >>>> - I think those statements are needed and are not obvious. >>>> >>>> - 4: last item MUST be break stop code. Is a decoder supposed to >>>> barf a bundle if this is not true? More generally, same question >>>> applies for all MUSTs stated only in terms of what the encoding must >>>> match. >>>> >>>> - Let's add a general statement, somewhere, to the effect that >>>> the bundle protocol agent MAY discard any malformed bundle it >>>> receives. >>>> >>>> - 4.1.1: why >1 CRC type? That seems bogus. None or strong seems >>>> better to me. (And I'd go for a crypto hash for strong.) I assume >>>> the WG discussed this and found that there are real use-cases for >>>> each of those specified. While those don't need to be in the spec, >>>> can someone tell me what they are as I'm not at all sure, e.g. why a >>>> 16 bit CRC is useful as an option. >>>> >>>> - The WG discussed this and settled on these options. See email >>>> list traffic starting on 18 January 2016. >>>> >>>> - 4.1.3: "enables anonymous bundle transmission" - that's >>>> overstated, chances are that something in the CLA will be >>>> identifying, or allow re-identification, so I think what you want to >>>> say is that omitting the source EID helps with, but does not ensure, >>>> nymity. >>>> >>>> - "Anonymous" doesn't mean you can't figure out who did it. >>>> "Anonymous" means the identity of whoever did it was not attached to >>>> it. The text is correct as written. >>> >>> Disagree. The term anonymous has a meaning which is not that. >>> >>>> >>>> - 4.1.5.1: RFC3986 is the correct reference here, so the spec text >>>> is correct as-is. It may however be worth taking a look at the >>>> whatwg web page that has sometimes claimed to supercede 3986 for the >>>> browser-related things in which whatwg have an interest. >>>> That's just in case there're some useful error handling >>>> considerations on the whatwg web page, (on the day you look at >>>> it;-). It's also the case that since BP EIDs are URIs, it's possible >>>> that strings that comply with today's or yesterday's whatwg web page >>>> may end up in the BP, so it'd be good to know if any of those (that >>>> are not valid according to 3986) might cause a problem with the CBOR >>>> encoding. >>>> >>>> - If the text is correct, let's leave it. If someone discovers >>>> that it is in error for one or more of the reasons proposed, then >>>> let's fix it. >>>> >>>> - 4.1.5.2: Danger, metaphysics! "Every node MUST be a member of at >>>> least one singleton endpoint." This entire section is over-thought. >>>> I think all you need to say is that nodes the emit bundles need to >>>> have an EID they can use as a source EID for as long as necessary. >>>> >>>> - I disagree. The section is exactly enough-thought. >>> >>> See point (B) above:-) And "exactly"? :-) >>> >>>> >>>> - 4.2.1: this entire section is duplicative. That's a bad idea. >>>> >>>> - If the text that it duplicates can be identified then we should >>>> remove the duplication. >>>> >>>> - 4.2.2: 2nd para is badly written - that'd encourage coders to use >>>> the values 8,9,10 and 11 in ways that might be unwise. >>>> >>>> - The text says nothing about using any values in any manner, for >>>> good or ill. It only says how many elements are in the array. >>>> >>>> - 4.2.2: wrt "anonymous" see earlier comment >>>> >>>> - Correct as written, as noted above. >>>> >>>> - 4.2.2: description of creation time is duplicative, except the >>>> earlier text didn't cover relative time. >>>> >>>> - This section is not duplicative, it is expansive. >>>> >>>> - 4.3.3: Is "Bundle Age Block" a good name? BAB used to mean another >>>> type of block, so that could confuse maybe. (That said, I forget how >>>> long we're had this name.) >>>> >>>> - There are no longer any Bundle Authentication Blocks. "Bundle >>>> Age Block" is a good name. >>>> >>>> - 4.3.4: Do you need to say that the hop limit MUST NOT be changed, >>>> once a hop count EB is added. Also, can any node add one of these, >>>> if one was not prevsiously present? >>>> >>>> - I agree, this needs to be clarified. >>>> >>>> - 5: It's not necessary to say that new RFCs can supercede this. >>>> That's just standard IEFF process. >>>> >>>> - I don't see what harm this does. For someone who is not >>>> steeped in standard IETF process, but wants to read the >>>> specification anyway, maybe it would be useful information. >>>> >>>> - 5.2: mentions "dispatch pending" as if I should know what that is >>>> - is all the retention constraint stuff sufficiently explained I >>>> wonder? (Personally I don't think you need to mandate all this stuff >>>> and you cannot tell if an implementation has done it or not so I'd >>>> not bother trying to be so prescriptive.) >>>> >>>> - All of the retention constraint stuff is explained in detail. >>>> I think it's necessary in order to ensure coherent behavior among >>>> the nodes of the network. >>> >>> See point (B) above:-) >>> >>>> >>>> - 5.4: "at the last possible moment... MUST..." that's a bit silly >>>> as it seems to require BP code inside a NIC which is not how this'll >>>> usually be implemented. >>>> >>>> - I don't understand the objection. "Last possible moment" is >>>> very clearly in the scope of the operation of the CLA, which is BP >>>> code. If that happens to be embedded in a NIC, fine, but that's not >>>> relevant. >>>> >>>> - 5.5: I'm not convinced that the MUSTs here are right for all DTNs. >>>> I reckon that 5.5 could just as well say "MAY delete" and the BP >>>> would be fine. That might also provide some additional flexibility >>>> for some rounting schemes. That said, I won't press on this - if >>>> this doesn't resonate with folks now, and later turns out to be >>>> useful, I don't think we'd have such a hard time modifying BPAs >>>> where needed. >>>> >>>> - Here again I think the normative language is necessary in >>>> order to ensure coherent behavior among the nodes of the network. >>> >>> See point (B) above. >>> >>>> >>>> - 5.6: Again, this is overly prescriptive. >>>> >>>> - I disagree, again because the normative language is necessary >>>> in order to ensure coherent behavior among the nodes of the network. >>>> >>> >>> See point (B) above. >>> >>>> - 5.6, step 4: I wonder if an implementer will get all this >>>> right. >>>> >>>> - It has been implemented. The implementation works fine. >>> >>> Yeah, but you've been doing this for ages, it's a new implementer >>> we need to consider, starting from the RFC. >>> >>>> >>>> - 5.9: Badly implemented, re-assembly can create a memory >>>> consumption DoS vector, perhaps esp. if attempted on a >>>> non-destination node. It'd be better to warn about that. And >>>> maybe change from MAY for in-path reassembly to SHOULD NOT. >>>> >>>> - I am doubtful that this specification should be a compendium of >>>> implementation tips. >>> >>> s/MAY/SHOULD NOT/ is way more than a tip >>> >>>> >>>> - 5.11: does this mean that a custodian MUST ignore a custody >>>> signal destined for some other custodian? >>>> >>>> - This text does not imply that the receiving node must ignore a >>>> custody signal destined for another custodian. It means exactly >>>> what it says, and no more. >>>> >>>> - Figure 6: I don't get when reason codes 5 to 8 would really be >>>> used. Are they in fact needed? (They seem a bit implementation >>>> specific to me, but I've not gone looking.) >>>> >>>> - DTNRG thought these codes would be needed. Let's get more >>>> deployment experience before deciding that they are not. >>>> >>>> - section 8: First sentence is bogus. >>>> >>>> - Not bogus, but not necessary. Sure, let's delete it. >>>> >>>> - section 8: [SECO] isn't a good reference. It's outdated and I >>>> doubt will be picked up. >>>> >>>> - Okay. >>>> >>>> >>>> >>> >>> _______________________________________________ dtn mailing list >>> dtn@ietf.org https://www.ietf.org/mailman/listinfo/dtn >>> >> >> _______________________________________________ dtn mailing list >> dtn@ietf.org https://www.ietf.org/mailman/listinfo/dtn >> >> > > _______________________________________________ > dtn mailing list > dtn@ietf.org > https://www.ietf.org/mailman/listinfo/dtn > >
- [dtn] working group last call on draft-ietf-dtn-b… Marc Blanchet
- Re: [dtn] working group last call on draft-ietf-d… Marc Blanchet
- Re: [dtn] working group last call on draft-ietf-d… Templin, Fred L
- Re: [dtn] working group last call on draft-ietf-d… Burleigh, Scott C (312B)
- Re: [dtn] working group last call on draft-ietf-d… Brian Sipos
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Templin, Fred L
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Spencer Dawkins at IETF
- Re: [dtn] working group last call on draft-ietf-d… I-Viswanathan, Kapaleeswaran
- Re: [dtn] working group last call on draft-ietf-d… Birrane, Edward J.
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Rick Taylor
- Re: [dtn] working group last call on draft-ietf-d… Templin, Fred L
- Re: [dtn] working group last call on draft-ietf-d… Rick Taylor
- Re: [dtn] working group last call on draft-ietf-d… Lucas Kahlert
- Re: [dtn] working group last call on draft-ietf-d… Burleigh, Scott C (312B)
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Carsten Bormann
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Burleigh, Scott C (312B)
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Burleigh, Scott C (312B)
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell
- Re: [dtn] working group last call on draft-ietf-d… Burleigh, Scott C (312B)
- Re: [dtn] working group last call on draft-ietf-d… Stephen Farrell