[ippm] Warren Kumari's Discuss on draft-ietf-ippm-route-09: (with DISCUSS and COMMENT)
Warren Kumari via Datatracker <noreply@ietf.org> Tue, 11 August 2020 16:10 UTC
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Date: Tue, 11 Aug 2020 09:10:05 -0700
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Subject: [ippm] Warren Kumari's Discuss on draft-ietf-ippm-route-09: (with DISCUSS and COMMENT)
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Warren Kumari has entered the following ballot position for draft-ietf-ippm-route-09: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-ippm-route/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- I have 2 DISCUSS points. I think that both should be easy to address... 1: "While most of the routers perform load balancing on flows using Equal Cost Multiple Path (ECMP), a few still divide the workload through packet-based techniques. The former scenario is defined according to [RFC2991], while the latter generates a round-robin scheme to deliver every new outgoing packet. ECMP uses a hashing function to ensure that every packet of a flow is delivered by the same path, and this avoids increasing the packet delay variation and possibly producing overwhelming packet reordering in TCP flows." Round-robin / "per packet" is a form ECMP, and RFC2991 doesn't "define" just the former, it explains both, and recommends the flow based / hashed approach. RFC 2991 describes a number of approaches (e.g Modulo-N Hash, Hash-Threshold, Highest Random Weight (HRW)) and makes some good suggestions, but the text as written isn't correct. 2: "In IPv6, it is sufficient to be routed identically if the IP source and destination addresses and the FlowLabel are constant, see [RFC6437]." Many routers currently ignore the FlowLabel and use other header info, like port-numbers. The sentence might(?) be true in an idealized network, but in the real world isn't. Some additional text should solve this... ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- Questions / Comments: 1: "Although primarily intended for hosts communicating on the Internet with IP, the definitions and metrics are constructed to be applicable to other network domains, if desired." This above says "with IP", but then the rest implies it works with other things too - I suggest dropping the "with IP" part, unless this does work with other protocols? 2: " Also, to specify a framework for active methods of measurement which use the techniques described in [PT] at a minimum, and a framework for hybrid active-passive methods of measurement, such as the Hybrid Type I method [RFC7799] described in [I-D.ietf-ippm-ioam-data](intended only for single administrative domains), which do not rely on ICMP and provide a protocol for explicit interrogation of nodes on a path." This is a really long / hard to read sentence - can you split it into multiple? I had to read it multiple time and am still having a hard time with the nested clauses. Perhaps: "This also specifies a framework for active methods of measurement which uses the techniques described in [PT], as well as a framework for hybrid active-passive methods of measurement(such as the Hybrid Type I method [RFC7799])." 3: " Node Identity The unique address for Nodes communicating within the network domain. For Nodes communicating on the Internet with IP, it is the globally routable IP address(es) which the Node uses when communicating with other Nodes under normal or error conditions. " I'm not sure I understand -- this says the "unique address" and also "IP address(es)" - it cannot be both singular/unique and multiple. This definition needs clarification or a pointer to later in the document. 4: "Cooperating Node Nodes that MUST respond to direct queries for their Node identity as part of a previously agreed and established interrogation protocol. " I don't think that the "MUST" works here -- I think s/MUST/do/ (or s/MUST//). 5: " Hop A Hop MUST contain a Node Identity, and MAY contain arrival and/ or departure interface identification, round trip delay, and an arrival timestamp." - this definition also doesn't really seem to define something, and I think needs to be rewritten or dropped. 6: "Routing Class A route that treats equally a class C of different types of packets (unrelated to address classes of the past)". I think that it is really unfortunate that the term "class C" was chosen for this - I understand that there is a clarification, and don't really expect you to change it, but it needlessly makes the document harder to read for people who naturally associate Class A, B, C, D with classful addresses. I recognize that this terminology comes from RFC2330, but it is till confusing. An additional clarification that this term is being used because of history would probably help. 7: "Next define a *singleton* definition for a Hop on the path, with sufficient indexes to identify all Hops identified in a measurement interval." I'm not sure that "singleton" is a well understood term outside of software engineering, and that you need to better explain it (esp because you have felt it important enough to emphasize). Perhaps "data structure to uniquely identify a hop" or similar? 8: " o If a pair of discovered Nodes identify two different addresses, then they will appear to be different Nodes. o If a pair of discovered Nodes identify two different IP addresses, and the IP addresses resolve to the same Node name (in the DNS), then they will appear to be the same Nodes." Please either include "IP" in both or neither of the above, otherwise it sounds like it is a differentiating factor. 9: " UDP and TCP are used when a particular characteristic needs to be verified, such as filtering or traffic shaping on specific ports (i.e., services). " TCP traceroute is also used when ICMP responses are not received - while "such as filtering" *could* cover this, it would require squinting... 10: "Furthermore, either Paris-traceroute or Scamper is capable of unveiling the many available paths between a source and destination (which are visible to this method)." Visible to *which* method? The one described in this doc? The methods implemented in Paris-traceroute/Scamper? Nits: 1: "1.1. Issues with Earlier Work to define Route" It seems that this is missing a word after "Route" - perhaps metric? Also, I understand the Title Case, but please either drop it, or uppercase D in define. 2: "Paris-traceroute allows its users to measure RTD in every hop of the path for a particular flow." s/measure RTD/measure the RTD/ 3: You seem to be using multiple ways of adding emphasis (*something*, --from the Observation Point --, etc). This is confusing / doesn't follow existing style.
- [ippm] Warren Kumari's Discuss on draft-ietf-ippm… Warren Kumari via Datatracker
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- Re: [ippm] Warren Kumari's Discuss on draft-ietf-… MORTON, ALFRED C (AL)