Re: [Anima] WGLC on draft-ietf-anima-stable-connectivity-03 - Respond by July 28, 2017

Toerless Eckert <tte@cs.fau.de> Tue, 19 September 2017 18:53 UTC

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Date: Tue, 19 Sep 2017 20:53:23 +0200
From: Toerless Eckert <tte@cs.fau.de>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
Cc: Anima WG <anima@ietf.org>
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References: <5D36713D8A4E7348A7E10DF7437A4B927CDFE66F@NKGEML515-MBX.china.huawei.com> <136a3ebd-dedb-9e2b-86be-a7d5fd12ad9b@gmail.com> <20170803010809.GA12136@faui40p.informatik.uni-erlangen.de> <a12a758e-9edc-14c0-a4e5-a051b83c9e97@gmail.com> <20170914211845.GA30086@faui40p.informatik.uni-erlangen.de> <475b3f59-5cda-0d35-aee7-cedf204d9f5f@gmail.com> <20170918053847.GA31832@faui40p.informatik.uni-erlangen.de> <761b1200-10ac-7dd1-267b-c0890c9cfd27@gmail.com>
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Subject: Re: [Anima] WGLC on draft-ietf-anima-stable-connectivity-03 - Respond by July 28, 2017
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Thanks, Brian!

Sheng: i think/hop i am trough all outstanding issues with stable-connectivity. Please
decide what to do next to move to next stage, eg: another WG last call or pass to
IETF/IESG.

Cheers
    Toerless

On Tue, Sep 19, 2017 at 08:11:56AM +1200, Brian E Carpenter wrote:
> This is embarassing. For some reason I completely missed the announcement
> of draft-ietf-anima-stable-connectivity-05, until today.
> 
> I have now looked at the -05 and -06 versions and I'm happy with the result.
> 
> Regards
>    Brian
> 
> On 18/09/2017 17:38, Toerless Eckert wrote:
> > Thanks, Brian:
> > 
> > The "OLD" paragraph you list was from -04. After your review i had already
> > changed this in -05 to
> > 
> > NEW:
> > 
> >    To connect IPv4 only management plane devices/applications with the
> >    ACP, some form of IP/ICMP translation of packets IPv4<->IPv6 is
> >    necessary.  The basic mechanisms for this are defined in SIIT
> >    ([RFC7915]).  There are multiple solutions using this mechanisms.  To
> >    understand the possible solutions, we consider the requirements:
> > ....
> > 
> > http://tools.ietf.org/tools/rfcdiff/rfcdiff.pyht?url1=https://tools.ietf.org/id/draft-ietf-anima-stable-connectivity-04.txt&url2=https://tools.ietf.org/id/draft-ietf-anima-stable-connectivity-05.txt
> > 
> > I also did spend a good amount of time because of your -04 review and prior
> > request by mohammed to detail in the following parapgraphs the possible
> > options in more detail.  That text leverages the 'SIIT' term and
> > discusses the EAM solutions (RFC7757 is best).
> > 
> > Given how this is an informational OPS document,
> > i think it is helpfull to elaborate on the understood details of
> > requirements and how known current solutions fit them.
> > 
> >  The fact that none of the
> > currently defined NAT solutions provides for the most simple possible
> > configuration (aka: minimum number of prefix EAM's to configure) is
> > also IMHO a perfectly valid outcome for an OPS document.
> > 
> > It could mean that users will simply accept the need for longer mnaual
> > NAT config (long list of 1:1 mappings) or vendors implement a proprietary
> > EAM (explicit address mapping) CLI to make it simpler. Or users will
> > move faster to IPv6 on the NOC ;-)
> > 
> > So, for the time being, i just commited -06 with the second fix.
> > 
> > Let me know what you folks think about WG last call status of
> > the stable connectivity draft.
> > 
> > Cheers
> >     Toerless
> > 
> > On Fri, Sep 15, 2017 at 11:05:51AM +1200, Brian E Carpenter wrote:
> >> To cut a long story short, here's a friendly suggestion. The goal is to avoid
> >> comments during IETF/IESG review that the NAT text is too vague:
> >>
> >> OLD
> >>    To bridge an IPv4 only management plane with the ACP, IPv4 to IPv6
> >>    NAT can be used.  This NAT setup could for example be done in Rt1r1
> >>    in above picture to also support IPv4 only NMS hots connected to
> >>    NOClan.
> >>
> >> NEW
> >>    To bridge an IPv4-only management plane with the ACP, IPv4 to IPv6
> >>    translation [RFC 6145] could be used. This could for example be done in Rt1r1
> >>    in the above picture to also support IPv4-only NMS hosts connected to
> >>    NOClan. Details of the address mapping to be used would depend on
> >>    the exact scenario and are not specified here.
> >>
> >> And yes, I like this:
> >>
> >>> i'd suggest to replace the "split-horizon" sentence with:
> >>>
> >>> Operators may therefore need to use a private DNS setup for the ACP ULA
> >>> addresses. This is the same setup that would be necessary for using
> >>> RFC1918 addresses in DNS. See for example [RFC1918] section 5, last
> >>> paragraph. In [RFC6950] section 4, these setups are discussed in more detail.
> >>
> >> Regards
> >>    Brian
> >>
> >> On 15/09/2017 09:18, Toerless Eckert wrote:
> >>>
> >>> Hi Brian, 
> >>>
> >>> Sorry, for the delay. I have not sen further feedback on stable-connectivity-05
> >>> bside this mail of yours. See answers below, let me know if you want me to rev
> >>> with the one possible textual improvement or if we think -05 is good enough.
> >>>
> >>> Cheers
> >>>     Toerless
> >>>
> >>> On Fri, Aug 04, 2017 at 11:31:37AM +1200, Brian E Carpenter wrote:
> >>>> I'm just coming back on a couple of points. Generally -05 is almost there...
> >>>>
> >>>>> See the rewritten SIIT section. IMHO, there can be no simpler "network" based
> >>>>> address translation. Where network based means that the translation happens
> >>>>> in some device he network operator needs to provision. Like the ACP edge device.
> >>>>> Or even an additional address translation device.
> >>>>>
> >>>>> So, the only IMHO easier option is when the OS of the NMS host would internally
> >>>>> have IPv4/IPv6 translation so the device/VM looks to the outside like full IPv6.
> >>>>
> >>>> Yes, that is exactly the effect of 464XLAT in the end-system (not in the
> >>>> router).
> >>>
> >>> I found rfc6877 a confusing read, but from what i figure, it's not exactly what
> >>> i was thinking of: with rfc6877, you still need the server side to have a reachable/mappable
> >>> IPv4 address, and that is something any device in the ACP does not have naturally.
> >>> (aka: NOC server as client connecting to ACP device, ACP device is server).
> >>>
> >>> If i already need to set up some other form of NAT to give an ACP device an outside IPv4
> >>> address, then 464XLAT does not buy me any simplifications.
> >>>
> >>> I was rather thinking of taking the NAT network function that i was describing
> >>> and simply embody them in a set of linux NAT rules configured on on the NOC linux
> >>> system that runs the IPv4-only NMS application. Aka: Not a novel NAT scheme,
> >>> but just a way to avoid having to deal with the problem in the network (adding a NAT
> >>> device you would otherwise not need):
> >>>
> >>> Its a NMS host problme, deal with it in the NMS host. If you can not change the app,
> >>> let the OS do the NAT. Of course, this would not work for the poor customer who bought
> >>> a black-blox NMS soution which may run windows, or where you can not configure the
> >>> linux. Then again, nowadays, most NOC components should be software in VMs, and
> >>> for those, you should certainly be able to do the NAT in the vswitch of the server.
> >>>
> >>> In any case: my interest in expanding the NAT section further is quite limited.
> >>> The whole goal of the NAT section was to explain that you need 1:1 address mapping
> >>> and that you can hack this up in likely most available routers with NAT support,
> >>> but do not consider this to be a good long term solution but use it as a stopgap
> >>> to upgrade your NOC software to IPv6.
> >>>
> >>> No idea why IETF draft/RFC doesn't allow me to write such a simple paragraph ;-))
> >>>
> >>> So, let me know if you feel strongly anything that should be added/modified to the
> >>> NAT section.
> >>>
> >>>>> Alas, i didn't have the time to investigate these options. And most likely if at
> >>>>> all you could only make those work for linux.
> >>>>
> >>>> Linux or Windows, yes. In a vendor's router o/s, who knows? But maybe they
> >>>> will all support IPv6 anyway?
> >>>
> >>> Lets hope so, yes.
> >>>
> >>>>> So, for now i just remove the note and clarified the last sentence a bit.
> >>>>>
> >>>>> If there is anything specific to be said bout why 464XLAT might be better
> >>>>> longer term, let me know and i can add it. For now it looks like yet another
> >>>>> network device configured option to me, but i have not tried to understand it
> >>>>> all the way.
> >>>>
> >>>> I think you'd need one of the 464XLAT authors to have a look at the scenario,
> >>>> because I don't claim to understand it all.
> >>>
> >>> Well, the analysis i made above (server must support IPv4 as stated in the RFC)
> >>> makes me discount it as a more beneficial option to mention.
> >>>
> >>>>>>>    Using current registration options implies that there will not be
> >>>>>>>    reverse DNS mapping for ACP addresses.
> >>>>>>
> >>>>>> Really? I assume we're talking about two-faced DNS, and afaik nothing
> >>>>>> stops an operator providing reverse mapping in the private DNS.
> >>>>>> That seems to be implied by the following paragraphs, so the text
> >>>>>> seems inconsistent anyway.
> >>>>>
> >>>>> I know it under the name "split-horizon DNS". Is there any reference ?
> >>>>
> >>>> The DNS community in the IETF hates split DNS so much that
> >>>> not much has been written about it. I did find these:
> >>>> https://tools.ietf.org/html/rfc6950#section-4
> >>>> https://tools.ietf.org/html/rfc7157#section-6.3
> >>>> https://tools.ietf.org/html/draft-richardson-homenet-secret-gardens
> >>>
> >>> RFC1918 actually explains it succinctly without giving it a name.
> >>> RFC4193 only tells you what you shouldn't do with DNS. How helpfull ;-)
> >>>
> >>> So, let me know if you think it's worth creating another stable-connectivity rev,
> >>> i'd suggest to replace the "split-horizon" sentence with:
> >>>
> >>> Operators may therefore need to use a private DNS setup for the ACP ULA
> >>> addresses. This is the same setup that would be necessary for using
> >>> RFC1918 addresses in DNS. See for example [RFC1918] section 5, last
> >>> paragraph. In [RFC6950] section 4, these setups are discussed in more detail.
> >>>
> >>> Cheers
> >>>     Toerless
> >>>
> >>>> Regards,
> >>>>     Brian
> >>>
> >>
> >> _______________________________________________
> >> Anima mailing list
> >> Anima@ietf.org
> >> https://www.ietf.org/mailman/listinfo/anima
> > 

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