Re: [dtn] working group last call on draft-ietf-dtn-bpbis

["Burleigh, Scott C (312B)" <[e-mail]>]

Fair enough.  I am happy to leave this up to the wisdom of the WG.

Scott

-----Original Message-----
From: Stephen Farrell [mailto:[e-mail]] 
Sent: Monday, March 27, 2017 2:19 PM
To: Burleigh, Scott C (312B) <[e-mail]>; Marc Blanchet <[e-mail]>; dtn <[e-mail]>
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:[e-mail]] Sent: Monday, March 27, 2017 1:37 
> PM To: Burleigh, Scott C (312B) <[e-mail]>; Marc 
> Blanchet <[e-mail]>; dtn <[e-mail]> 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:[e-mail]] Sent: Monday, March 20, 2017
>> 3:06 PM To: Burleigh, Scott C (312B)
>> <[e-mail]>; Marc Blanchet 
>> <[e-mail]>; dtn <[e-mail]> 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:[e-mail]] 
>>> On Behalf Of Stephen Farrell Sent:
>>> Monday, January 23, 2017 7:33 PM To: Marc Blanchet 
>>> <[e-mail]>; dtn <[e-mail]> 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.
>>> 
>>> 
>>> 
>> 
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