I am the assigned Gen-ART reviewer for this draft. For background on Gen-ART, please see the FAQ at < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>. Please resolve these comments along with any other Last Call comments you may receive. Document: draft-ietf-ccamp-flexi-grid-fwk-05 Reviewer: David Black Review Date: August 2, 2015 IESG Telechat date: August 6, 2015 Summary: This draft is on the right track, but has open issues described in the review. This draft requires significant GMPLS expertise to fully understand, but is generally well written and clear. It describes the use of a GMPLS control plane with flexible optical networks that can vary optical frequency assignment on a per-link basis along an optical path. All of the issues that I found are minor, and some of them may be mostly reflections of my lack of GMPLS expertise. Major issues: None Minor issues: [1] 3.2.5 - the last bullet item is not completely clear to me. What does it mean for two slot compositions to be the same? Is this saying that the same set of effective frequency slots need to be present end-to-end for the media channel? I suspect not, but I don't understand what is intended. [2] p.21 last sentence in 1st para: Regardless of the actual encoding, the LSP setup message specifies a minimum frequency slot width that needs to be fulfilled in order to successful establish the requsted LSP. Should "minimum frequency slot width" be "minimum effective frequency slot width"? I think it's possible for the effective frequency slot width to be smaller than all of the individual slot widths involved in the absence of frequency shifters/converters. [3] p.21 - RSA acronym is unfortunate, due to collision w/widespread usage of that acronym for a security algorithm. I strongly suggest changing to another acronym (e.g., R+SA). [4] 4.8.4 - The information model is informal or abstract (can't generate anything from it), even though RBNF was used - this should be noted. [5] 5.5 - I'm surprised that the first requirement (neighbor discovery support) is a MAY. I wonder about its operational consequences, and at the very least suggest expanding Section 8 to discuss them. The text in 5.5 should be expanded to add some explanation of how things work when there's no neighbor discovery support. Nits/editorial comments: Section: 3.2.1 - Editorial suggestion: Changing "+" -> "+/-" in the formula for nominal central frequency and re-defining n as a non-negative integer would be slightly clearer. p.6 - please state that slot width is +/- wrt nominal central frequency. p.8 - Fig 4 could use a bit more explanation - the two frequency slots occur at different points along the path. Nit: First nominal central frequency 'X' in Fig 5 needs to move 2 chars left. Section 4 - TE link term shows up w/o acronym expansion or definition. Please define it before use. Sections 4.2 and 4.3 - this may be my unfamiliarity, but it would have helped to have some sort of heads-up at the start of the figures that the top (non-GMPLS) portion of the figures prior to Figure 12 are entirely in the optical domain. Perhaps explaining what the two planes are (and how they're realized/implemented) in Figure 8 would help. Last paragraph on p.16: "trnaponders" -> "transponders". Also, I saw "transceivers" earlier - if that's the same concept, only one term should be used. p.19 - Even after expanding acronyms, I don't understand this sentence: If two OTSis must be switched to different ports, it is better to carry them by different FSC channels, and the media layer switch is enough in this scenario. A sentence or two explaining what an "FSC channel" is earlier in that paragraph would help. p.21, 1st para: messages, and a specific frequency slot can be requeste on any s/requeste/requested p.21: In GMPLS the requested effective frequency slot is represented to the TSpec present in the Path message, and the effective frequency slot is mapped to the FlowSpec carried in the Resv message. I believe those are RSVP-TE messages - that should be stated. p. 22: d. n can change, but m needs to remain the same along the path. This ensures that the effective frequency slot remains valid, but allows the frequency slot to be moved within the spectrum from hop to hop. In full generality, that may require the ability to shift or convert a frequency slot, which is a concept that doesn't appear to occur in the draft prior to this point. Figures 15 and 16 need their variables (e.g., m_a, FSb) somehow labelled or explained After Figure 16, the switch to the EFS acronym is a surprise, given the extensive prior usage of the spelled-out term. This paragraph contains all uses of the EFS acronym - I suggest removing that acronym and spelling out the term. Section 4.6: I don't understand why this sentence is in the middle of the paragraph - it doesn't seem to describe an example of different slot width granularities: Consider a node with an application where the nominal central frequency granularity is 12.5 GHz and where slot widths are multiples of 25 GHz. I'd suggest removing it. 5.1.1. What is L-band? This is the first time it's mentioned. idnits 2.13.02 didn't find anything that needs attention. Thanks, --David ---------------------------------------------------- David L. Black, Distinguished Engineer EMC Corporation, 176 South St., Hopkinton, MA  01748 +1 (508) 293-7953             FAX: +1 (508) 293-7786 david.black at emc.com        Mobile: +1 (978) 394-7754 ----------------------------------------------------