Hi, Thanks for this document. Here are my AD review comments for draft-ietf-opsawg-ipfix-srv6-srh-07. There is an obvious disclaimer here that I'm not an IPFIX expert, and I appreciate that one of the authors is ;-).
Moderate level comments: (1) p 4, sec 3. IPFIX Information Elements srhIPv6Section Exposes the SRH and its TLVs as specified in Section 2 of [RFC8754] as series of n octets in IPFIX. It isn't clear to me exactly what this is? Does this cover the whole SRH, or just the "SRH TLVs" section? From looking at the examples, I think that this exposes the whole SRH, in which case, I think that the description could be clearer. Please can you also update the description in the IANA section. (2) p 12, sec 5.11. srhSegmentIPv6EndpointBehavior ElementID: TBD11 Description: The 16-bit SRv6 Endpoint behavior. Assigned values and their meanings are provided in the "SRV6 Endpoint Behavior" IANA registry [IANA-IPFIX]. Is this linking to the right reference? It looks like this should be the SRv6 IANA registry rather than the IPFIX registry. Minor level comments: (3) p 4, sec 3. IPFIX Information Elements srhSegmentIPv6BasicList Ordered basicList [RFC6313] of zero or more 128-bit IPv6 addresses in the SRH that represents the SRv6 segment list. As specified in Section 2 of [RFC8754], the Segment List is encoded starting from the last segment of the SR Policy. That is, the first element of the Segment List (Segment List[0]) contains the last segment of the SR Policy, the second element contains the penultimate segment of the SR Policy, and so on. In terms of naming, I note that the "IPv6" seems to turn up in difference places in the IEs defined in this draft. It might be awkward to change, but wouldn't the names be more consistent (e.g., with RFC8754), if they put IPv6 all in the same place? I was going to suggest putting them at the start (e.g., ipv6srh...), but looking at https://www.iana.org/assignments/ipfix/ipfix.xhtml, it looks like the "IPv6" is often put at the end of the name. E.g., srhSegmentIPv6BasicList -> srhSegmentBasicListIPv6, etc. Note, I'm happy to defer to Benoit's judgement as an IPFIX expert here ... (4) p 4, sec 3. IPFIX Information Elements srhSegmentIPv6LocatorLength The number of significant bits. Together with srhSegmentIPv6 it enables the calculation of the SRv6 Locator. I suggest "The number of significant bits" is reworded to something like: "The IPv6 location length specified as the number of significant bits." If you update this, then please can you make a similar clarification for the IANA entry description. (5) p 9, sec 5.6. srhSegmentIPv6ListSection Description: The SRH Segment List as defined in section 2 of [RFC8754] as series of n octets. Am I right to assume that the length of the array must be a multiple of 16? Is that worth specifying at all? (6) p 26, sec Appendix A. IPFIX Encoding Examples Figure 8: Data Set Encoding Format for SRH Section Note, I don't really know IPFIX well enough to validate the examples, hence I'm trusting the authors that they are correct. Nit level comments: (7) p 2, sec 1. Introduction These IEs are used to export SRv6 active segment and its control plane protocol, the SRv6 segment list, the next SRv6 node and its type, and then numbers of SRv6 segments left. "then numbers" -> "the numbers"? (8) p 4, sec 3. IPFIX Information Elements srhSegmentIPv6ListSection Exposes the SRH Segment List as defined in Section 2 of [RFC8754] as series of n octets in IPFIX. I suggest "series of n octets" -> "sesies of octets", here and below. (9) p 12, sec 6.1. SRv6 Segment List The srhSegmentIPv6BasicList encodes the SRv6 segment list with a basicList, specified in the IPFIX Structured Data [RFC6313]. This encoding offers the advantage to the data collection that the different IPv6 addresses are already structured as a list, without the need of post processing. However, this method requires some extra processing on the exporter, to realize the BasicList data mapping. Should it be "to the data collector" or is "to the data collection" correct? (10) p 12, sec 6.1. SRv6 Segment List The srhSegmentIPv6ListSection, on the other hand, encodes the list of IPv6 addresses as an octetArray. This doesn't impose any data flow manipulation on the exporter, facilitating the immediate export. However, the data collection MUST be able to decode the IPv6 addresses according the SR specifications. Compared to the srhSegmentIPv6BasicList, the srhSegmentIPv6ListSection flow records length is slightly reduced. 'according the' -> 'according to the' Regards, Rob _______________________________________________ OPSAWG mailing list OPSAWG@ietf.org https://www.ietf.org/mailman/listinfo/opsawg