[v6ops] AD Review of draft-ietf-v6ops-slaac-renum
Warren Kumari <warren@kumari.net> Mon, 10 August 2020 17:18 UTC
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From: Warren Kumari <warren@kumari.net>
Date: Mon, 10 Aug 2020 13:17:42 -0400
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To: draft-ietf-v6ops-slaac-renum.all@ietf.org, IPv6 Operations <v6ops@ietf.org>
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Subject: [v6ops] AD Review of draft-ietf-v6ops-slaac-renum
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Hi there authors! Thank you for this document - it is clear, useful, and addresses a real issue... Unfortunately there were discussions at the plenary (and then further discussions in the IESG) on polishing the readability, etc of documents before sending them for IETF LC / balloting, and so I've been extra "picky" on typos, grammar, etc. I also ran it though some automated grammer checking tools, so apologies for all the nits. Addressing these should make the document easier to read, and so result in better / faster review.... If I'd been a bit cleverer, I would have just asked for the source document so that there is less copying and pasting... Thanks again for the document, and apologies again for all of the nits... Questions / comments: 1: "In scenarios where the CPE router crashes and reboots, the CPE may be leased (via DHCPv6-PD) a different prefix from the one previously leased, and therefore advertise (via SLAAC) the new prefix on the LAN side." I understand what this sentence is trying to say, but it took a few readings - I kept reading it that the CPE device itself may be leased, and then getting confused. I'm not quite sure how to fix it, but does: "In scenarios where the CPE router crashes and reboots, the CPE may be obtain (via DHCPv6-PD) a different prefix from the one previously leased, and therefore advertise (via SLAAC) the new prefix on the LAN side." work? 2: "If such a push results in changing the /64 subnet configured on a particular network..." - I suggest dropping the "/64" - it doesn't add anything to the sentence is is likely to just attract controversy / questions. Abstract: O: This document documents this problem, and discusses operational workarounds that may help to improve network robustness. P: This document documents this issue and discusses operational workarounds that may help to improve network robustness. Intro: O: However, there are a number of scenarios that may lead to P: However, there several scenarios that may lead to O: ... nodes on the local network will continue using stale prefixes for an unacceptably long period of time, thus... P: ... nodes on the local network will continue using stale prefixes for an unacceptably long time, thus... O: Hosts will normally configure addresses for the new prefix, P: Hosts will typically configure addresses for the new prefix, O: In particular there has been evidence that some 802.1x P: In particular, there has been evidence that some 802.1x O: Automated device config management system performs periodical config push to network devices... P: Automated device config management system perform periodic config pushes to network devices... O: If such a push results in changing the /64 subnet configured on a particular network, hosts attached to that network would not get notified about the subnet change and their addresses from the "old" prefix will not deprecated. P: If such a push results in changing the /64 subnet configured on a particular network, hosts attached to that network would not get notified about the subnet change and their addresses from the "old" prefix will not be deprecated. C: Missing "be" O: Lacking any explicit signaling to "deprecate" the previously-advertised prefixes P: Lacking any explicit signaling to deprecate the previously-advertised prefixes C: Unclear why deprecate is in quotes. O: hosts may continue to employ the previously-configured addresses which P: hosts may continue to employ the previously-configured addresses, which O: -- whether because of egress-filtering by the CPE or ISP, or because responses to such packets be discarded or routed elsewhere. P: -- whether because of egress-filtering by the CPE or ISP, or because responses to such packets are discarded or routed elsewhere. C: or "packets being discarded or routed elsewhere." O: ... retained and also actively employed for new communications instances for unacceptably long period of time.. P: ... retained and also actively employed for new communications instances for an unacceptably long period of time ... O: However, for robustness reasons it is also paramount P: However, for robustness reasons, it is paramount O: flash-renumbering events occur and the network is unable to explicitly notify hosts about such condition. P: flash-renumbering events occur and the network is unable to explicitly notify hosts about such conditions. C: plural. O: Section 2 analysis this problem in more detail. P: Section 2 analyzes this problem in more detail. O: Section 4 describes possible future work to better mitigate the aforementioned problem P: Section 4 describes possible future work to mitigate the aforementioned problem Section 2: O: As noted in Section 1, the problem discussed in this document exacerbated by a number of different parameters and behaviours. P: As noted in Section 1, the problem*s* discussed in this document are exacerbated by a number of different parameters and behaviours. C: I don't really like "parameters" here - perhaps "default parameters" or just drop it? O: Each of the following sections analyze each of them in detail. P: The following sections analyze each of them in detail. C: "The authors of this document understand that, for a number of reasons (such as the ones stated above), IPv6 deployments may employ dynamic prefixes " - as it is now a WG / IETF document, I think that you should remove the "The authors" bit (unless you *really* want to keep it) Section 2.2: O: One common example for the use of timers is when implementing reliability mechanisms where a packet is transmitted, and unless a response is received, a retransmission timer will go off to trigger retransmission of the original packet. P: One use of timers is when implementing mechanisms where a packet is transmitted, and, unless a response is received, a timer will fire to trigger retransmission of the original packet. O: For obvious reasons, the whole point of using timers is that in problematic scenarios, they will go off, and trigger some recovery action. P: For obvious reasons, the whole point of using timers in this way is that, in problematic scenarios, they trigger some recovery action. O: However, under problematic circumstances such as where the corresponding network P: However, under problematic circumstances, such as where the corresponding network O: The Preferred Lifetime of an address can be reduced to any value to avoid the use of a stale prefix to be employed for new communications. P: The Preferred Lifetime of an address can be reduced to any value to avoid using a stale prefix for new communications or The Preferred Lifetime of an address can be reduced to any value to avoid the use of a stale prefix for new communications. Section 2.4: O: Whenever prefix information has changed, a SLAAC router should not only advertise the new information, but should also advertise the stale information with appropriate lifetime values (both "Preferred Lifetime" and "Valid Lifetime" set to 0), such that there is explicit signaling to SLAAC hosts to remove the stale information (including configured addresses and routes). P: Whenever prefix information has changed, a SLAAC router should not only advertise the new information, but should also advertise the stale information with appropriate lifetime values (both "Preferred Lifetime" and "Valid Lifetime" set to 0), in order to provide explicit signaling to SLAAC hosts to remove the stale information (including configured addresses and routes). C: Even better would be to split this into separate sentences... Thank you again! W -- I don't think the execution is relevant when it was obviously a bad idea in the first place. This is like putting rabid weasels in your pants, and later expressing regret at having chosen those particular rabid weasels and that pair of pants. ---maf
- [v6ops] AD Review of draft-ietf-v6ops-slaac-renum Warren Kumari
- Re: [v6ops] AD Review of draft-ietf-v6ops-slaac-r… Fernando Gont
- Re: [v6ops] AD Review of draft-ietf-v6ops-slaac-r… Warren Kumari
- Re: [v6ops] AD Review of draft-ietf-v6ops-slaac-r… Owen DeLong