Summary: Has a DISCUSS. Has enough positions to pass once DISCUSS positions are resolved.
[edited to fix a typo in the section number, but otherwise unchanged from the original position on the -19] This being a discuss ballot notwithstanding, the protocol mechanisms here seem pretty well thought-out; I'm just wanting changes to how they are described. There seems to be an internal inconsistency in Section 4.3, between "[t]he PCE SHOULD add the scheduled LSP into its scheduled LSP-DB and update its scheduled TED" and "[t]he stateful PCE is required to update its local scheduled LSP-DB and scheduled TED". (I think the "SHOULD" one is wrong, personally.) Let's also take a closer look at the precise interdependency between the B bit and PD bit -- Section 5.1 implies that the PD bit itself cannot be set in the absence of the B bit, referring forward to Section 5.2.2, but Section 5.2.2 seems to only say that you need both the B and PD bits set in order to send SCHED-PD-LSP-ATTRIBUTE. Bits being set as a prerequisite for sending the TLV is a subtly different condition than having the one bit itself depend on the other, with correspondingly different error handling. Section 6.6 refers to the "LSP-ERROR-CODE TLV (Section 7.3.3) which is not defined in this document, rather, the reference should be to § 7.3.3 of RFC 8231.
I'm pretty sympathetic to Alvaro's not-quite-Discuss, but also am not quite prepared to elevate it to Discuss level (and incur the responsibility to determine what changes are necessary to resolve it). I note several editorial comments and nits below, but those remarks are not comprehensive. Abstract so as to enable Labeled Switched Path (LSP) scheduling for path computation and LSP setup/deletion based on the actual network resource usage and the duration of a traffic service in a centralized network environment as stated in RFC 8413. Just looking at this text in isolation, it's not entirely clear if the event that is scheduled is the LSP activation, creation, calculation, or something else, and whether it is just the computed path that depends on the resource usage/traffic duration, or if other things like the frequency of scheduling or the existence of an LSP at all would be dependent on those. Presumably the rest of the document will clarify, but perhaps there is some wordsmithing possible here. Section 1 letting other services use it when this service is not using it. The requirement of scheduled LSP provision is mentioned in [RFC8231] and nit(?): I think s/provision/provisioning/ [RFC7399]. A solution for providing more efficient network resource usage for traffic engineering is desired. Also, for deterministic nit: I don't really follow the connection between these two sentences -- "a solution for [...] is desired" seems to be a general re-statement of the problem, whereas the previous discussion has been discussing, essentially, the benefits of the proposed solution. Section 2.1 Hmm, RFC 8231 says that it itself takes the definitions for "Active Stateful PCE", "Passive Stateful PCE", and several other terms from RFC 8051; we should probably short-circuit the reference chain(s). Scheduled TED: Traffic engineering database with the awareness of scheduled resources for TE. This database is generated by the PCE from the information in TED and scheduled LSP-DB and allows knowing, at any time, the amount of available resources (does not include failures in the future). I'd consider "the expected amount of available resources (discounting the possibility of failures in the future)". Section 4.1 The LSP scheduling allows PCEs and PCCs to provide scheduled LSP for customers' traffic services at its actual usage time, so as to improve the network resource efficient utilization. nit: s/resource efficient utilization/resource utilization efficiency/ In case of implementing PCC-initiated scheduled LSPs, before a PCC delegates a scheduled LSP, it MAY use the PCReq/PCRep messages to Just to check: there is some risk that the computed path might change between this query and when the LSP actually becomes active? learn the path for the scheduled LSP. A PCC MUST delegate a scheduled LSP with information of its scheduling parameters, including the starting time and the duration using PCRpt message. I suggest "When delegating a scheduled LSP, a PCC MUST include its scheduling parameters, including [...]", to be clear about what cases the "MUST" applies to. (It might also be worth saying what a PCE should do if it receives a delegation request for a scheduled LSP that does not include the requisite parameters.) For a multiple PCE environment, a PCE MUST synchronize to other PCEs within the network, so as to keep their scheduling information synchronized. There are many ways that this could be achieved: one such mechanism is described in [I-D.litkowski-pce-state-sync]. Which way is used to achieve this is out of scope for this document. [...] I'd suggest restructuring how this paragraph is laid out (akin to Alvaro's comment). Specifically, it's an intrinsic fact that if you're in a multi-PCE environment, you have to have inter-PCE synchronization or the stat skew causes problems. That's not new with this document; what we are most interested in saying is that, in addition to the existing need to synchrnoize the TED and LSP-DB, when scheduled LSPs are in use you also have to synchronize the SLSP-DB and have each PCE reconstruct the Scheduled TED (or synchronize the Scheduled TED as well). The ways to perform such synchronization are hardly worth mentioning, except to the extent that existing mechanisms cannot handle sending the extra information. The scheduled LSP can also be initiated by PCE itself. In case of nit: missing article (perhaps "by a PCE itself"). scheduled LSP based on the local policy. For the former SCHED-LSP- ATTRIBUTE TLV (see Section 5.2.1) MUST be included in the message I suggest s/For the former/In the former case, the/ where as for the latter SCHED-LSP-ATTRIBUTE TLV SHOULD NOT be nits: s/where as/whereas/, s/SCHED-LSP-ATTRIBUTE/the SCHED-LSP-ATTRIBUTE/ included. Either way the synchronization to other PCEs should be done when the scheduled LSP is created. I recognize that the BCP 14 keywords are not being used, but earlier we said "shall synchronize" but here it's just "synchronization should be done"; it's probably worth making these consistent. In both modes, for activation of scheduled LSPs, the PCC could initiate the setup of scheduled LSP at the start time by itself or wait for the PCE to update the PCC to initiate the setup of LSP. I'm worried about the "could initiate [...] or wait". While it's true that either party could take the initiative, doesn't there need to be an agreement between them about which one it will be, to avoid the risk of the LSP not actually geting instantiated at the start time? Similarly on the scheduling usage expires, the PCC could initiate the nit: s/expires/expiry/ or s/expires/expiration/ (Same comment about "could" as above.) Section 4.2.2 When an LSP is configured with a scheduling interval such as "[Ta, Tb] repeats 10 times with a repeat cycle a week" (representing 11 scheduling intervals), a path satisfying the constraints for the LSP in every interval represented by the periodical scheduling interval is computed once. And then the LSP along the path is set up to carry traffic in each of the scheduling intervals. If there is no path satisfying the constraints for some of the intervals, the LSP will not be set up at all. This seems to say that the same path must be used for each recurrence of the scheduled event, precluding some optimizations that might be desired in the face of other (unscheduled or differently scheduled) load. Is that intended? Section 188.8.131.52 When an LSP is configured with elastic time interval "[Ta, Tb] within -P and Q", a path is computed such that the path satisfies the constraints for the LSP in the time period from (Ta+Xv) to (Tb+Xv) and |Xv| is the minimum value for Xv from -P to Q. That is, [Ta+Xv, To check my understanding, this mention of |Xv| is indicating that the PCE attempts to limit the deviation from the requested interval, using an absolute value metric to indicate distance from the requested value? It might be worth putting in a few more words to indicate that this optimization is being performed; just "is the minimum value" could be confusing. Section 184.108.40.206 During grace periods from (Ta-GB) to Ta and from Tb to (Tb+GA), the LSP is up to carry traffic (maybe in best effort). This point seems pretty key to having grace periods at all. In particular, if there is no difference between the traffic-handling properties for the grace period and the "main interval", then the grace period is more simply handled by the entity requesting the interval (i.e., "just ask for a larger interval"). The fact that we propose to give different traffic-handling behavior during the grace period should be emphasized, in order to justify the existence of the protocol element. In the absence of such justifying text, I would propose to remove the grace-period feature as needless complexity. Section 4.3 For PCE-Initiated Scheduled LSP, the stateful PCE can compute a path for the scheduled LSP per requests from network management systems automatically based on the network resource availability in the scheduled TED, send a PCInitiate message with the path information nit: s/, send/ and send/ back to the PCC. Based on the local policy, the PCInitiate message could be sent immediately to ask PCC to create a scheduled LSP (as nit: s/ask PCC/ask the PCC/ o Based on the configuration (and the C flag in scheduled TLVs), when it is time (i.e., at the start time) for the LSP to be set up, either the PCC triggers the LSP to be signaled or the delegated PCE sends a PCUpd message to the head end LSR providing the updated path to be signaled (with A flag set to indicate LSP activation). We haven't discussed the C flag yet, so a reader is left wondering "how do I know whether the PCC or PCE is going to take initiative?". We could reword, perhaps like "When it is time for the LSP to be set up (i.e., at the start time), based on the value of the C flag for the scheduled TLV, either the PCC [...]". Similar changes would be applicable in later sections as well. Section 4.4 Are there any special considerations for modifying a periodic scheduled LSP after some recurrences have already happened? What about for modifying any scheduled LSP that is currently active (whether before the chage, after the change, or both)? Section 5.1 After a PCEP session has been established, a PCC and a PCE indicates its ability to support LSP scheduling during the PCEP session establishment phase. For a multiple-PCE environment, the PCEs should also establish PCEP session and indicate its ability to support LSP scheduling among PCEP peers. The Open Object in the Open message Does a PCE need to refrain from advertising scheduling support to PCCs if its PCE peers do not all support scheduling? scheduling among PCEP peers. The Open Object in the Open message contains the STATEFUL-PCE-CAPABILITY TLV defined in [RFC8231]. Note that the STATEFUL-PCE-CAPABILITY TLV is defined in [RFC8231] and updated in [RFC8281] and [RFC8232]". In this document, we define a new flag bit B (SCHED-LSP-CAPABLITY) flag for the STATEFUL-PCE- CAPABILITY TLV to indicate the support of LSP scheduling and another flag bit PD (PD-LSP-CAPABLITY) to indicate the support of LSP periodical scheduling. I note that (e.g.) RFC 8623 does not seem to give mnemonic names for the individual bits, so our "bit B" and "bit PD" seem a bit out of place. Section 5.2 Only one of these TLV SHOULD be present in the LSP object. In case more than one scheduling TLV is found, the first instance is processed and others ignored. It seems that this wording "more than one scheduling TLV" might apply to some hypothetical future TLV type for a different variation of scheduled LSPs. If that would be undesirable, we could reword to mention the two TLV types by name. Section 5.2.1 Please note that this formulation (number of seconds since a fixed time) is invariant to leap seconds, but that conversions from current UTC time to it might need to account for leap seconds. (Or if you want to ignore leap seconds, say that.) C (1 bit): Set to 1 to indicate the PCC is responsible to setup and remove the scheduled LSP based on the Start-Time and duration. I suggest noting that the PCE holds these responsibilities when the bit is set to zero. Start-Time (32 bits): This value in seconds, indicates when the scheduled LSP is used to carry traffic and the corresponding LSP must be setup and activated. Value of 0 MUST NOT be used in Start-Time. Note that the transmission delay SHOULD be considered when R=1 and the value of Start-Time is small. I don't understand why start-time of 0 is disallowed (for at least the R=0 case) -- that would disallow requesting a start time that happens to land on the time when the time counter wraps around, for no reason. The Start-Time indicates a time at or before which the scheduled LSP must be set up. The value of the Start-Time represents the number of seconds since the epoch when R bit is set to 0. When R bit is set to 1, it represents the number of seconds from the current time. In addition, it contains an non zero grace-before and grace-after if I suggest s/it/the SCHED-LSP-ATTRIBUTE TLV/; it's easy to misread the "it" as referring to the "Start-Time" from the previous paragraph. grace periods are configured. It includes an non zero elastic range Are the Grace-Before/Grace-After fields set to zero when grace periods are not configured? lower bound and upper bound if there is an elastic range configured. (Likewise for elastic-range.) Section 5.2.2 Opt: (4 bits) Indicates options to repeat. A new registry "Opt" under SCHED-PD-LSP-ATTRIBUTE is created. When a PCE receives a TLV with a Opt value not defined, it does not compute any path for the LSP. It generates a PCEP Error (PCErr) with a PCEP-ERROR object having Error-type = 4 (Not supported object) and Error- value = 4 (Unsupported parameter). Have we thought about what kind of negotiation might be needed in the case where a new Opt value is defined? Though the possibility currently seems unlikely, this error message does not seem sufficient to indicate which Opt value is problematic. NR: (12 bits) The number of repeats. In each of repeats, LSP carries traffic. Maybe say that NR==0 is equivalent to using SCHED-LSP-ATTRIBUTE (to avoid questions of 0- vs. 1-indexing)? Section 6.x We mention in several places "the scheduled TLVs" for the LSP object, but this seems misleading, since at most one scheduled TLV should be present in a given object. Perhaps "a scheduled TLV" would be better? Section 6.2 Perhaps it's worth noting that in the PCE-initiated case there is the option to avoid using the scheduled LSP TLVs (and, to some extent, PCUpd at all), since the PCE can just not tell the PCC about the scheduled path until its start-time occurs. Section 6.4 request the path computation based on scheduled TED and LSP-DB. A PCC MAY use PCReq message to obtain the scheduled path before delegating the LSP. [if my previous comment about "subject to change" results in text changes, similar changes would apply here] Section 6.5 Just to check: the scheduled TLV should still be included in the response even for a negative response? (Also, same comment about "obtain the scheduled path before delegating".) Section 8 Since we deal with scheduled events, we should remind implementations to do something reasonable when their current time jumps. Jumps can be forward or backward, and might cross boundaries for when LSPs should be (in)active. The presence of a significant time correction may be indicative of other (configuration) issues, and falling back to a conservative stance (keep LSPs active?) might be appropriate. Similarly, some discussion of how things break when there is clock skew between PCC and PCE might be useful (we already have a requirement for clock synchronization in discussion of the R flag). on the network. Thus, such deployment should employ suitable PCEP security mechanisms like TCP Authentication Option (TCP-AO) [RFC5925] or [RFC8253]. The procedure based on Transport Layer Security (TLS) in [RFC8253] is considered a security enhancement and thus is much better suited for the sensitive information. PCCs may also need to nit: TCP-AO would be considered a "security enhancement" as well (compared to a baseline of unprotected TCP). Perhaps the intent is to say that the TLS procedure from RFC 8253 additionally provides confidentiality protection to the conveyed data? nit: "such deployments" plural. Section 9.1 When configuring the parameters about time, a user SHOULD consider leap-years and leap-seconds. I know I mentioned leap seconds earlier as well, but this feels like a cop-out. We can tell the reader in much more detail how leap years and seconds will affect their calculations, which in aggregate will be much more efficient than making each reader think it through for themself. Section 9.2 nit(?) "view the capability" (singular) sounds like it's just seeing whether the scheduled LSP functionality is enabled or not, a boolean value. If the intent is to say that the specific (e.g., per-tunnel) state should be visible, then this should be reworded accordingly. Section 9.4 Is there something to say about checking that LSPs are activated/disabled at the appropriate times for scheduled and periodic events? Section 9.5 Are there any requirements on PCE-to-PCE synchronization protocols that now need to carry the SLSP-DB? Section 10.1.1 Is there anything to say about why the two reserved values are reserved?
I concur with Alvaro Retana’s point (2) and (3), that since time synchronization is key to functionality clarified normative guidance is needed. I support Ben Kaduk's DISCUSS position. ** Section 2.1. Thank you for providing a mapping of terms to references. ** Consider using normative language in the following places: -- Section 5.2.1. Per “The Start-Time indicates a time at or before which the schedule LSP must be set up”, should this be a normative MUST? -- Section 8. Per “Thus, such deployment should employ suitable PCEP security mechanisms …”, why not a normative SHOULD? ** Editorial Nits: -- Section 1. Typo. s/can not/cannot/ -- Section 5.2.1. Typo. s/an non zero/a non zero/g
[ section 1 ] * "the service really being used" -> "the service is really being used"? [ section 4.1 ] * "SHALL check ... and computes" -> "... and compute" * "on the scheduling usage expires" -> "on scheduled usage expiration"? [ section 4.2.2 ] * If there is no possible path do you want some text, maybe even just a lowercase should, about "should report to an administrator" or something? [ section 4.3 ] * In the first of the 4 bullet points at the end of this section, should the "required" and "shall" be capitalized? [ section 4.5 ] * "In other case," -> "In all other cases," or just "Otherwise,"? [ section 5.1 ] * Perhaps there's a way to strengthen the "PD requires B" text by saying what an endpoint should do if it sees PD without B? [ section 5.2.1 & 5.2.2 ] * R bit. WRT to R=0 and the wraparound, it would seem to me that in this case the receiver really needs to check if start-time is less than the current time, and if so treat that as wrap-around (2106) + start-time number of seconds. Otherwise, I think you'll need to be more precise about what it means to be "near" the wrap-around. Even still, if times are not sync'd carefully and the start-time is not a moderate amount of time in the future there remains a chance that an endpoint could receive a start-time it perceives as "in the past". What should an endpoint in this circumstance? Yet another alternative is to take a flag bit to indicate that start-time is after the wrap-around, and say that by 2242 CE some other solution should be found. :-) * Duration: Is a value of 1 just as nonsensical as 0? What about a value of 0 if grace-before and grace-after are non-zero? I may not understand the grace and elastic uses properly, but it seems to me that the thing to forbid is an "effective duration" of 0 (i.e. factoring in grace or elastic values). * Grace and Elastic fields: If it cannot provide both simultaneously why have both fields? What just have a "lower" and "upper" pair of fields and choose a new flag value to indicate whether the fields are grace values or elastic values?
Section 2.1: * "Passive Stateful PCE" is listed in the imported terminology, but not used elsewhere in the document. Sections 5.2.1 & 5.2.2: * I had the same questions Erik did about the R-bit. Section 7: The text here is unchanged since version -09 of this document, which recorded no known implementations, and was posted almost a year ago. Is that still the case now? Section 10.1.1: This section defines a new registry but doesn't explicitly describe the fields of that registry like Section 10.1.2 does. It's nice to be explicit about these things, in my opinion.
I think that this document still needs work before publication. I consider the first 3 points below to be close to DISCUSS-worthy. (1) In general, it feels like an editorial pass is needed to tighten up the language used as specification in this document. There are several places where the language feels loose -- as an example (from §4.4): In PCC-Initiated case, the PCC can send a PCRpt message for the scheduled LSP with updated parameters as well as scheduled information included in the SCHED-LSP-ATTRIBUTE TLV (see Section 5.2.1) or SCHED-PD-LSP-ATTRIBUTE TLV (see Section 5.2.2) carried in the LSP Object. The PCE would take the updated resources and schedule into considerations and update the new path for the scheduled LSP to the PCC as well as synchronize to other PCEs in the network. In case path cannot be set based on new requirements, the previous LSP will not be impacted and the same should be conveyed by the use of empty ERO in the PCEP messages. "the PCC can send" Does it have to? If the information is not sent, then the PCE will not be able to calculate the path, so something stronger than "can" seems to be needed. "PCE would take" Does this mean that it is optional? I can imagine how the PCE may have local policies affecting the action...but I shouldn't have to imagine anything. "should be conveyed" Again, do you have to? Are there cases when it is ok not to do it? Not everything needs rfc2119 key words, but in some cases they would help. In this case, I can see a couple of variations possible. rfc2119> ...the PCC MUST send...the PCE SHOULD take...MUST be conveyed... non-rfc2119> ...the PCC sends...the PCE takes...is conveyed... (2) §4.1: "a PCE MUST synchronize to other PCEs within the network...Which way is used to achieve this is out of scope for this document." If the synchronization mechanism is out of scope, how can an implementation be compliant with this specification? IOW, if there's nothing to normatively refer to, then normative language shouldn't be used, or a mechanism should be mandated. In either case, because synchronization between the PCEs seems important for this specification, I would like to also see a discussion about the specific effects on LSP scheduling instead of the generic pointer to rfc7399. §4.3 says that the "stateful PCE...shall send a PCRpt message with the scheduled LSP to other PCEs...to achieve...synchronization." Even though normative language is not used, the intent seems to specifically point at using PCRpt messages for synchronization... Besides the confusing use of language, rfc8231 defines PCRpt as a "message sent by a PCC to a PCE to report the current state of an LSP", but I didn't see where the use if defined between PCEs -- maybe I missed it. §6.1 does reinforce that the "Path Computation State Report (PCRpt) is a PCEP message sent by a PCC to a PCE to report the status of one or more LSPs as per [RFC8231]....This message is also used to synchronize the scheduled LSPs to other PCE as described in [RFC8231]". But this last point is what I can't find in rfc8231. (3) This whole document is about scheduling LSPs, which would seem to require time synchronization. However, I found only one mention: "It is necessary to synchronize the clocks of the PCEs and PCCs when relative time is used." Should this sentence use normative language? Is there a recommended way to achieve time synchronization? This seems to be an important manageability consideration that impacts network operations. (4) rfc8413 should be a Normative reference because it "provides a framework that describes and discusses the problem, and defines an appropriate architecture for the scheduled reservation of TE resources", which is the basis for the extensions defined in this document. (5) §2.1: Some of the terminology terms have 2 references -- that caught my attention. For example, the definition of TED points at both rfc5440 and rfc8231. rfc5440 has a definition, but rfc8231 points at rfc4655. Luckily, the definitions in rfc5440 and rfc4655 are the same...but the added indirection through rfc8231 is unnecessary. Please revalidate the references and include only one. (6) §2.1: "Duration: This value indicates the time duration..." Please don't use "duration" to define "duration". Maybe s/time duration/length of time (7) §4.1: "A PCC MUST delegate a scheduled LSP with information of its scheduling parameters, including the starting time and the duration using PCRpt message." This sentence seems to refer to the use of the new TLVs defined later in the test. Please include a forward reference to make it easier for the reader to figure out how this action would be done. (8) §4.3: "The PCE SHOULD add the scheduled LSP into its scheduled LSP-DB and update its scheduled TED." When is it ok for the PCE not to add this information? IOW, why is MUST not used? If the information is not added, what is the effect on the required synchronization? Later in this section: "The stateful PCE is required to update its local scheduled LSP-DB and scheduled TED with the scheduled LSP." Even though normative language is not used here, the intent of requiring an update to the databases seems different than above and results in confusion. (9) §4.3: "the PCC knows that it is a scheduled path" How? I'm sure that it is through the contents of the messages. Please be specific. (10) §5.1: "After a PCEP session has been established, a PCC and a PCE indicates its ability to support LSP scheduling during the PCEP session establishment phase." Is it after or during? (11) §5.1: "...the STATEFUL-PCE-CAPABILITY TLV defined in [RFC8231]. Note that the STATEFUL-PCE-CAPABILITY TLV is defined in [RFC8231]..." Redundant. (12) §5.1: "we define a new flag bit B (SCHED-LSP-CAPABLITY) flag...B (LSP-SCHEDULING-CAPABILITY..." The names don't match. (13) §5.1: "Setting PD bit requires setting B bit as specified in 5.2.2." That is not specified in §5.2.2. However, it brings up the question about the interpretation of only receiving the PD bit set -- I'm assuming that it should be ignored unless the B but is also set, right? If so, please specify it! (14) §5.2: "this LSP is requesting scheduled parameters" The request is by the PCC, not the LSP... (15) §5.2: "scheduled LSP attribute TLV" Even though it may be obvious, the SCHED-LSP-ATTRIBUTE TLV is not called "scheduled LSP attribute TLV" anywhere in the document. (16) §5.2: "For periodical LSPs, the SCHED-PD-LSP-ATTRIBUTE TLV can be used in LSP Object for each periodic scheduled LSP carried in the PCEP messages." Don't you *have* to use it? Otherwise, how would the periodic nature be known? (17) §5.2: "Only one of these TLV SHOULD be present in the LSP object. In case more than one scheduling TLV is found, the first instance is processed and others ignored." This section talks about both the SCHED-LSP-ATTRIBUTE and the SCHED-PD-LSP-ATTRIBUTE TLVs -- the sentence sounds as if only one of them (either one) should be present. Please rephrase -- it may be better to define this behavior for each TLV independently (in §5.2.*). (18) §5.2.1: "This TLV MUST NOT be included unless both PCEP peers have set the B..." What should the receiver do if the TLV is received when both peers didn't set the B bit? (19) §5.2.1: "Just before the wraparound, if the time at which the LSP is to be activated is after the wraparound..." I don't know how that is possible. (20) §5.2.1: "...non-zero grace period or elastic range, but it MUST NOT provide both for an LSP." What should a receiver do if both sets are non-zero? (21) §5.2.2: "This TLV MUST NOT be included unless both PCEP peers have set the B...and PD..." What should the receiver do if the TLV is received but both bits were not set? (22) §5.2.2: "A new registry "Opt" under SCHED-PD-LSP-ATTRIBUTE is created." The registry is not part of the definition of the field...this sentence is not needed here. (23) §5.2.2: "Opt value not defined" I think you may mean an unknown value (or maybe unsupported). (24) Nits: s/following terminologies are re-used/following terminology is re-used s/computes a path/compute a path/g s/by PCE itself/by a|the PCE itself s/setup of LSP/setup of an LSP s/ask PCC/ask the PCC s/In PCC-Initiated case/In the PCC-Initiated case/g s/In PCE-Initiated case/In the PCE-Initiated case/g s/establish PCEP session/establish a PCEP session s/Setting PD bit requires setting B bit/Setting the PD bit requires setting the B bit s/presence of SCHED-LSP-ATTRIBUTE/presence of the SCHED-LSP-ATTRIBUTE s/in LSP Object/in the LSP Object/g s/one of these TLV/one of these TLVs s/B (LSP-SCHEDULING-CAPABILITY bit)/B (LSP-SCHEDULING-CAPABILITY) bit/g s/Following flags/The following flags s/remains same as/remain the same as in the s/Options =/Opt = s/In each of repeats, /During each repetition §6.1: s/described in [RFC8231]/described in [RFC8231].
Thank you for the work put into this document. Please find below one non-blocking COMMENTs. I hope that this helps to improve the document, Regards, -éric == COMMENTS == -- Section 220.127.116.11 -- May be am I failing to understand this part of the sentence "|X| is the minimum value from 0 to max(P, Q)" as it is not the same as "where -P <= X <= Q" or does the "|X|" not represent the absolute value of X ? == NITS == -- Section 18.104.22.168 -- Please use "are" rather than "is" in "Note that both Ta and Tb is shifted by the same 'X'"
I found that document somewhat hard to read and support Alvaro's comment that this document would benefit from an editorial pass. However, it is worth noting that I don't have much knowledge/experience of PCE. A few comments: Top level comment - should this draft be marked as "Experimental" if it unclear whether it will be implemented? 22.214.171.124. Elastic Time LSP Scheduling It wasn't quite clear to me how an end client would make use of elastic time scheduling. Is there some signalling mechanism to inform the client at the point in time that the tunnel has actually been set up, or otherwise how do they know when to make use of it? This might be worth clarifying in this section unless it is covered elsewhere. 126.96.36.199. Grace Periods I'm not really convinced that grace periods are worth it. I.e. the PCC client could trivially do the calculation and request the exact duration that they wanted which would slightly simplify the protocol messages. Is there any further justification as to why grace periods are requried? 5.2. LSP Object I'm not entirely convinced that it is that useful/necessary to have both messages. I would have probably just defined SCHED-PD-LSP-ATTRIBUTE TLV and treated the non repeating case as degenerate case (i.e. opt = "no-repeats", repeat-time-length = 0). 5.2.2. SCHED-PD-LSP-ATTRIBUTE TLV It isn't clear to me whether a client can make a request for it to repeat forever (until cancelled), and if so, how that would be indicated. Did you consider other encodings of the "Opt" and "Repeat-time-length" fields: - I would have added "seconds", "minute", "hours" to the "Opt" field and removed "Options = 5: repeat every Repeat-time-length". - I would then always combine the "Opt" field with the "Repeat-time-length" field, e.g. so that you could express repeat every 12 hours as: (opt="hours", repeat-time-length=12), or every 30 minutes as (opt="minutes", repeat-time-length=30), etc. Hopefully these comment help to improve this document. Regards, Rob