Note: This ballot was opened for revision 06 and is now closed.
I don't think the use of 2119 keywords adds value to this draft. The uses that I found seem more statement of fact than normative assertions. (That is, they describe the state of the world rather than give instructions or grant permission.) I suggest removing the capitalization and the 2119 reference, and just let the words have their plain English meanings.
Thank you for writing this, I think it is a useful document -- however, it does have a number of nits which would be nice to address (if you make any other edits). Nits: Section 1. Introduction O: "flow identification.The key" P: "flow identification. The key" R: missing space O: performance monitoring of MPLS flows when MPL is used for the encapsulation of user data packets. P: performance monitoring of MPLS flows when MPLS is used for the encapsulation of user data packets. R: Typo for MPLS? O: Indeed it is important that any flow identification technique be invisible to them and that no remnant of the identification of measurement process leaked into their network. P: Indeed it is important that any flow identification technique be invisible to them and that no remnant of the identification of measurement process leaks into their network. R: Tense / readability. Section 3. Loss Measurement Considerations O: Modern networks, if not oversubscribed, potentially drop relatively P: Modern networks, if not oversubscribed, generally drop relatively C: "potentially" makes it sound like this might happen. If a network isn't oversubscribed it usually won't drop packets. Section 4. Delay Measurement Considerations O: Most of the existing delay measurement methods are active measurement that depend on the extra injected test packet to evaluate C: I think that this should be "active measurements" or "active methods". I'm also confused by the singular of "packet". O: Also, for injected test packets, these may not be co-routed with the data traffic due to ECMP, or various link aggregation technologies all of which distribute flows across a number of paths at the network, or data-link and hence at the physical layer. C: This sentence is a run on / really confusing. I know what you are trying to say, but this doesn't communicate it well. Perhaps "Due to ECMP (or link aggregation techniques) injected test packets may traverse other links than the data traffic."? Still not great, but I think easier to parse. Section 5. Units of identification O: In particular note that there may be a need to impose identify at several different layers of the MPLS label stack. P: "identity" (or perhaps "identification"?) O: Such fine grained resolution may be possible by deep packet inspection, but this may not always be possible, or it may be desired to minimize processing costs by doing this only in entry to the network, and adding a suitable identifier to the packet for reference by other network elements. C: This feels like a run on. Also I *think* it is "fine-grained" and "on entry to the network" (nits) O: This allows for the case of instrumenting multiple LSPs operate between the same pair of nodes. P: This allows for the case of instrumenting multiple LSPs operating between the same pair of nodes. C: Readability.
I'm uncertain about the archival value of this document in the RFC series as the document seems to be written rather for wg-internal consumption only; however, I will not object to its publication. One additional minor comment in section 5: CURRENT: "An example of such a fine grained case might be traffic from a specific application, or from a specific application from a specific source, particularly if matters related to service level agreement or application performance were being investigated." Besides the duplication nit, I would like to suggest the following small change: PROPOSED: "An example of such a fine grained case might be traffic belonging to a certain service or from a specific source, particularly if matters related to service level agreement or application performance were being investigated." I'd say "service" is less specific than "application" and includes such things like e.g. a video service that is offered by the ISP.