Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6ops-cpe-slaac-renum-05: (with DISCUSS and COMMENT)
Fernando Gont <fgont@si6networks.com> Thu, 22 October 2020 15:20 UTC
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To: Erik Kline <ek.ietf@gmail.com>, Ted Lemon <mellon@fugue.com>
Cc: The IESG <iesg@ietf.org>, V6Ops Chairs <v6ops-chairs@ietf.org>, v6ops list <v6ops@ietf.org>, draft-ietf-v6ops-cpe-slaac-renum@ietf.org
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From: Fernando Gont <fgont@si6networks.com>
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Date: Thu, 22 Oct 2020 12:19:10 -0300
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Subject: Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6ops-cpe-slaac-renum-05: (with DISCUSS and COMMENT)
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On 22/10/20 11:28, Erik Kline wrote: > I agree. I just think then the text about "the lesser of two lifetime > values" doesn't quite read correctly nor give the impression that this > applies to things like ULA prefixes. I think it's probably pretty > easy to fix with minimal text. My shot at it: At the end of this: CE routers SHOULD set the Router Lifetime to ND_PREFERRED_LIMIT. CE routers SHOULD also set the PIO Preferred Lifetime to the lesser of the remaining preferred lifetime (see Section 3.1) and ND_PREFERRED_LIMIT, and the PIO Valid Lifetime to the lesser of the remaining valid lifetime and ND_VALID_LIMIT. Add: "If a ULA prefix is locally generated as specified in [RFC4193] and advertised on the LAN-side via PIO options, the corresponding PIO Preferred Lifetime and Valid Lifetime SHOULD be set to ND_PREFERRED_LIMIT and ND_VALID_LIMIT, respectively." At the end of: CE Routers providing stateful address configuration via DHCPv6 SHOULD set the DHCPv6 IA Address Option preferred-lifetime to the lesser of the remaining preferred lifetime and ND_PREFERRED_LIMIT, and the valid-lifetime of the same option to the lesser of the remaining valid lifetime and ND_VALID_LIMIT. Add: "If a ULA prefix is locally generated as specified in [RFC4193] and employed for stateful address configuration via DHCPv6, the corresponding DHCPv6 IA Address Option preferred-lifetime and valid-lifetime SHOULD be set to ND_PREFERRED_LIMIT and ND_VALID_LIMIT, respectively. Finally, for the DHCPv6-PD case, at the end of: CE Routers providing DHCPv6-PD on the LAN-side SHOULD set the DHCPv6 IA Prefix Option preferred-lifetime to the lesser of the remaining preferred lifetime and ND_PREFERRED_LIMIT, and the valid-lifetime of the same option to the lesser of the remaining valid lifetime and ND_VALID_LIMIT. Add: "If a ULA prefix is locally generated as specified in [RFC4193] and the CE Router provides DHCPv6-PD on the LAN-side, it SHOULD set the DHCPv6 IA Prefix Option preferred-lifetime to ND_PREFERRED_LIMIT, and the valid-lifetime of the same option to ND_VALID_LIMIT." Thoughts? P.S.: Bottom-line is that this is only special for ULA prefixes that are *locally* generated, since in that case there's only one lifetime involved (no "lifetimes" from the upstream). Thanks, Fernando > > On Thu, Oct 22, 2020 at 7:11 AM Ted Lemon <mellon@fugue.com> wrote: >> >> I think it’s reasonable to assume that in some situations a ULA will be generated and not remembered, or that the /48 will be remembered but the subnetting will not be. E.g. this could happen in an HNCP-delegated network pretty easily. The set of behaviors we are seeing in existing border routers fairly constrained with respect to what is theoretically possible and even reasonable. So I don’t think there’s a good reason to suggest different treatment for ULAs. >> >>> On Oct 22, 2020, at 01:37, Erik Kline via Datatracker <noreply@ietf.org> wrote: >>> >>> Erik Kline has entered the following ballot position for >>> draft-ietf-v6ops-cpe-slaac-renum-05: 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-v6ops-cpe-slaac-renum/ >>> >>> >>> >>> ---------------------------------------------------------------------- >>> DISCUSS: >>> ---------------------------------------------------------------------- >>> >>> [ section 3.2 ] >>> >>> * I absolutely agree in principle at these other lifetimes should be updated >>> to the shorter of the two applicable lifetimes, but I'm worried that this >>> text is not sufficiently precise. Specifically, this recommendation only >>> applies to options that depend in any way on the change in the delegated >>> prefix, yes? Perhaps just this qualifier is sufficient? >>> >>> For example, none of these comparative lifetime recommendations apply to >>> a stable ULA for a router that meets requirements ULA-[1..5] and chooses >>> to advertise a ULA /48 RIO and maybe even a ULA DNS server, I think. >>> >>> That being said, should this document also be saying that the ULA-derived >>> options SHOULD prefer the ND_{P,V}_LIMIT lifetime values, in case a reboot >>> causes a new ULA to be generated (i.e. the one supposedly in stable storage >>> is lost or otherwise unrecoverable)? >>> >>> >>> ---------------------------------------------------------------------- >>> COMMENT: >>> ---------------------------------------------------------------------- >>> >>> [[ comments ]] >>> >>> [ section 3.1 ] >>> >>> * With respect to the second bullet: the lifetimes need to be dynamically >>> *updateable*, not necessarily updated if, for example, the ND_{P,V}_LIMIT >>> values are always lower than the remaining PD lifetimes. In this situation, >>> the requirement is still that the lifetimes can be updated, but to the >>> casual observer of the steady state the RA contents might appear static >>> (e.g., while the PD'd prefix is continuously renewed). >>> >>> Maybe there's no text required here, but I didn't want a reader to be left >>> with the impression that no two RAs could be identical >>> >>> >>> [[ nits ]] >>> >>> [ section 3.3 ] >>> >>> * In the 2nd bullet's 2nd bullet (this might be easier if these lists were >>> numbered), it might be good to clarify that "the *deprecated* prefix can >>> simply be advertised..." >>> >>> >>> >>> _______________________________________________ >>> v6ops mailing list >>> v6ops@ietf.org >>> https://www.ietf.org/mailman/listinfo/v6ops > -- Fernando Gont SI6 Networks e-mail: fgont@si6networks.com PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
- [v6ops] Erik Kline's Discuss on draft-ietf-v6ops-… Erik Kline via Datatracker
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Ted Lemon
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Erik Kline
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Fernando Gont
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Fernando Gont
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Fernando Gont
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Fernando Gont
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Erik Kline
- Re: [v6ops] Erik Kline's Discuss on draft-ietf-v6… Fernando Gont