Re: Network merge [Re: RFC6724-bis?]

Brian E Carpenter <brian.e.carpenter@gmail.com> Tue, 27 September 2022 01:53 UTC

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Message-ID: <3aed4f01-7873-9e65-e5e7-233c1f2512cd@gmail.com>
Date: Tue, 27 Sep 2022 14:53:13 +1300
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Subject: Re: Network merge [Re: RFC6724-bis?]
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To: Mark Smith <markzzzsmith@gmail.com>
Cc: 6man WG <ipv6@ietf.org>
References: <66892DC8-6DA4-4DC8-85B0-E1E1647CD9F7@gmail.com> <CAN-Dau2QO5sxevJwUbOj+_wyiCdOjnPEZM14Jhevvkq4YZqU7Q@mail.gmail.com> <bc85e623-ef89-d2e2-4e33-b8ce0a4ec343@gmail.com> <CAN-Dau0Wbki6xwcEdy8ZK-pO9jeT6+8TKZgbmXWUgnkR+dRhBg@mail.gmail.com> <CAPt1N1=OmC+HNVGWbgj9JtGbpcuzKOgjZ1KXJm5mXgpji-G4Mw@mail.gmail.com> <6edcc5d8-edf1-51de-103c-a4ac6060fef6@gmail.com> <29689d645d22409b962f6c361d71e098@huawei.com> <CAN-Dau3rwi4X4NqLbHMmPQQ=i7y23Kz70JK09ggsXSxkJfT5xA@mail.gmail.com> <bf7c7d74cc7744ef8ded7d043ceb3e5e@huawei.com> <CAN-Dau0=LD9MTYKJQoSw=b9S25nmrNuqRSyLdsztFZscG8ZbUg@mail.gmail.com> <CAPt1N1kjOWh8R70pNO0eH9EJUH-v6HyxGMqxpy0N2hydHN33LQ@mail.gmail.com> <CAM5+tA9mqjrtq3pTggv1pA4fOYXUODkZHy74vs8cffVOrBefbQ@mail.gmail.com> <0b6886d3-5ea9-0a1d-8b16-4e17daeb6924@gmail.com> <CAM5+tA9dAjh0MTRG3922xTe3_aChHFa9AYCFCGmt395KwuvBYA@mail.gmail.com> <395554.1664189125@dooku> <56a897a426084f9381abaf770f1ea35e@huawei.com> <CAO42Z2xgMnVXeH9t0p_u7bg2fY-Gg+AagkFMMRJstX4E-f8FPQ@mail.gmail.com>
From: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Mark,

On 27-Sep-22 12:17, Mark Smith wrote:
> 
> 
> On Mon, 26 Sept 2022, 21:15 Vasilenko Eduard, <vasilenko.eduard=40huawei.com@dmarc.ietf.org <mailto:40huawei.com@dmarc.ietf.org>> wrote:
> 
>      >    > But how remote ULA prefix would be known to the local router?  If
>      >It can't, which is fine.
>      >If there are multiple ULAs after a merger, then we do what Brian and David described and send RIOs or PIOs.
> 
>     It is evident that A=0 is for something non-local.
> 
> 
> A=0 means the opposite of A=1, and A=1 has a specific meaning, nothing to do with non-local.

A=0 means don't do SLAAC for this prefix. L=0 means this PIO does not imply that the prefix is on-link. Prefix matches fc00::/7 means the prefix is ULA. I can't see any ambiguity in interpreting this both as RFC 8028 suggests and as "treat this /48 as locally reachable".

> 
> Define another flag if this is going to be the solution to the fault of putting ULA AAAAs in global DNS.

Defining and deploying a new flag is a lot harder.

> (Can it be adapted to the fault of putting link-local addresses in DNS?)

I doubt it, because an RA really has no business saying anything at all about fe80::/10.

    Brian

> 
> 
>     It would be especially needed if /64 would be put into the SASA policy table (then the remote prefix would be /64 too).
>     It may be needed for different /48 after the company merge.
> 
>     How to know what to put in this special PIO (A=L=0)? It looks like not automated at all.
> 
> 
> A sign that it's not solving the problem where it exists.
> 
> 
> 
>     Ed/
>     -----Original Message-----
>     From: Michael Richardson [mailto:mcr+ietf@sandelman.ca <mailto:mcr%2Bietf@sandelman.ca>]
>     Sent: Monday, September 26, 2022 1:45 PM
>     To: Vasilenko Eduard <vasilenko.eduard@huawei.com <mailto:vasilenko.eduard@huawei.com>>; 6man WG <ipv6@ietf.org <mailto:ipv6@ietf.org>>
>     Subject: Re: Network merge [Re: RFC6724-bis?]
> 
> 
>     Vasilenko Eduard <vasilenko.eduard@huawei.com <mailto:vasilenko.eduard@huawei.com>> wrote:
>          >> Now as to how to fix this without a global precedence for ULAs, I am
>          >> wondering about a PIO with L=0 and A=0 (exactly as recommended in RFC
>          >> 8028, but for other reasons). If a host sees such a PIO for a ULA
>          >> prefix, it could serve as a signal that the prefix is to be given a
>          >> suitable precedence, even though it is not on-link and not used for
>          >> SLAAC.
> 
>          >> I really like this.  I think it is the best solution.
> 
>          > But how remote ULA prefix would be known to the local router?  If
> 
>     It can't, which is fine.
> 
>     If there are multiple ULAs after a merger, then we do what Brian and David described and send RIOs or PIOs.
> 
>          > proper routing is in place then no problem exists in the first place,
>          > the whole FC/7 could be prioritized.
> 
>     I don't think that non-local ULAs *should* be prioritized.
>     I think that it's actually a problem as more and more sites use ULA for significant internal things, and those addresses leak into other sites.
> 
> 
>     --
>     Michael Richardson <mcr+IETF@sandelman.ca <mailto:mcr%2BIETF@sandelman.ca>>, Sandelman Software Works  -= IPv6 IoT consulting =-
> 
> 
> 
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