Hi Donald, Copying Martin for the 802.1Q normative reference question.
Please see inline. > -----Original Message----- > From: Donald Eastlake <d3e...@gmail.com> > Sent: 08 April 2021 22:08 > To: Rob Wilton (rwilton) <rwil...@cisco.com> > Cc: The IESG <i...@ietf.org>; draft-ietf-bess-evpn-oam-req-fr...@ietf.org; > bess-cha...@ietf.org; BESS <bess@ietf.org>; Matthew Bocci > <matthew.bo...@nokia.com> > Subject: Re: Robert Wilton's No Objection on draft-ietf-bess-evpn-oam-req- > frmwk-08: (with COMMENT) > > Hi Rob, > > On Thu, Apr 8, 2021 at 9:36 AM Robert Wilton via Datatracker > <nore...@ietf.org> wrote: > > > > Robert Wilton has entered the following ballot position for > > draft-ietf-bess-evpn-oam-req-frmwk-08: No Objection > > > >... > > > > ---------------------------------------------------------------------- > > COMMENT: > > ---------------------------------------------------------------------- > > > > Hi, > > > > Thanks for this document. > > > > It's a bit unclear to me whether the descriptions/definitions of > MIP/MEP/MA/MD > > are coming from CFM or RFC 6136. Section 1.1 suggests that they are > coming > > from CFM (but without a normative reference to 802.1Q), but the > terminology > > implies that they are being taken from RFC 6136. > > Although I have tweaked them a bit, the descriptions/definitions were > in the draft when I took up the pen along with the reference to RFC > 6136. So I don't know where they came from. Surely the important thing > is their accuracy. [RW] I guess I feel that subsequent parts of the document assume a more detailed understanding of what MIPS/MEPS are than is described in the terminology. This is fine, and I don't think that further text in the terminology is required, but it was unclear to me, that if a reader wanted to better understand what is meant by these terms whether they should be looking at RFC 6136 or 802.1Q, and I was hoping that the document could clarify/choose a definitive source reference. My impression, given how they are used, is that a reference to 802.1Q for CFM is probably most useful. > > > Certainly, there seem to be places in this document where more meaning > of > > these terms seems to be expected than what is provided in the > terminology > > section. Section 2.6 refers to CCMs, but I think that a reader would > only > > understand what these are if they have read CFM. Hence, I think that > this > > document would probably benefit from having a normative reference to > 802.1Q > > rather than informative. > > I have no problem with adding more references to 802.1Q but would > moving 802.1Q from Informational to Normative require a new Last Call > since it is not an IETF Standards Track document? [RW] Yes, I think that would be required. But I've not raised this as a discuss level concern so will defer to the responsible AD here. > > > Minor comments: > > > > 2.1 OAM Layering > > > > "and shows which devices have visibility into what OAM layer(s)." > > > > Perhaps indicate by the 'o' symbol. Otherwise the fact that the Link OAM > is the > > end point of the physical links, whereas the other OAM endpoints are may > cause > > confusion. > > I'm not sure exactly what you are saying. The ends of the Link OAM > correspond to the ports. The other types of OAM generally run between > the central control planes of the nodes. [RW] > Do you want me to add > something to the text about the 'o' symbols? ("and, as indicated by > where the "o"s line up, shows which devices have visibility into what > OAM layer(s).") Or what? [RW] Yes, this is what I was suggesting, but it is at the authors' discretion. > > > Figure 2: > > While I tried to give some hints in the details of this Figure, in > some of your comments below I think you are trying to read way too > much into fine details of this very high level diagram. [RW] Perhaps. I'm happy to leave it to the authors' discretion as to whether to change this but have given further comments below. > > > - Would it be helpful to move the 'o' marks to the end of the PE > devices, to > > line up with the Link OAM end points? > > > > - Is "Service CFM" the right term here? Does this mean "Service OAM - > CFM"? > > Probably should be "CFM (Service OAM)" and the PE "o" marks for it > should be moved to line up with the CE facing edge of the PE since > those ports are what are involved. Network OAM, such as BFD, logically > runs between central control planes of the PEs so having the "o" > centrally under the PE seems best to me. [RW] The reason that I suggested moving these (for figure 2 only, not figure 1) is because I interpret figure 2 as specifically talking about Ethernet EVPNs, using CFM and Link OAM. Figure 3 and the associated text also gives a description of the appropriate demarcation point for CE facing MIPS and MEPS and describes is as being much more closely aligned to ports (i.e., towards the PE forwarding mechanism) then a single central control plane location. Hence, I think that if I was drawing this diagram, with symbols to indicate the demarcation points, then I would probably have drawn it slightly differently, with the o symbols in slightly different places. Probably along with a short explanation on why it is different to figure 1, tying it to section 2.2. But as above, I'm happy to leave it to the authors to decide whether what I propose would make the document clearer. > > > - Probably helpful to add an informative reference to 802.3 Link OAM, > which is > > in figure 2. > > OK, that can be made into a reference. > > > 2.2 EVPN Service OAM > > > > - I'm not sure how clear "towards the device" is when the point is > already > > within the device. > > How about "towards the core of the device"? A port is one the edge of > a device so I think that saying it is "within the device" has a > slightly wrong connotation. [RW] I agree that "towards the core of the devices" is clearer. > > If you have two devices with 4 ports as follows: > P1-Dev1-P2----------P3-Dev2-P4 > CFM permits you to run tests between P1 and P2 or between P3 and P4 > that test the continuity through and switching fabric of the devices > without using a link. Of course, you can also run tests from P1 to P3 > or P2 to P3 or P1 to P4 or whatever. (Not all implementations of CFM > actually do all this. Some implement the MEPs/MIPs as virtual MEPs/MPs > in the ports that are actually implemented in the central control > plane of the device.) [RW] Yes. Hence why I was suggesting that moving the 'o' symbols on figure 2 may be clearer. > > > - The up and down arrows for the MEPS ("^" and "V") seem to potentially > make > > Figure 3 more confusing. Also "down" should be changed to "Down" in the > last > > CE. > > OK on the case change. So, on the ASCII art arrow heads, you think I > should just delete them? [RW] That would be my recommendation, but happy to leave it to the authors' discretion. > > > Nits: > > > > I'm not sure why the PE nodes are numbered by CE nodes are not. > > Since these numbers are never used in the text, I'm inclined to eliminate > them. [RW] Thanks, Rob > > Thanks, > Donald > =============================== > Donald E. Eastlake 3rd +1-508-333-2270 (cell) > 2386 Panoramic Circle, Apopka, FL 32703 USA > d3e...@gmail.com > > > Regards, > > Rob _______________________________________________ BESS mailing list BESS@ietf.org https://www.ietf.org/mailman/listinfo/bess