Re: A common problem with SLAAC in "renumbering" scenarios

Ole Troan <otroan@employees.org> Tue, 19 February 2019 12:22 UTC

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Subject: Re: A common problem with SLAAC in "renumbering" scenarios
From: Ole Troan <otroan@employees.org>
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Date: Tue, 19 Feb 2019 13:22:18 +0100
Cc: Sander Steffann <sander@steffann.nl>, 6man WG <ipv6@ietf.org>
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References: <60fabe4b-fd76-4b35-08d3-09adce43dd71@si6networks.com> <c16e0e1f-1ed2-ad88-80f1-070bdd8bccca@go6.si> <1F2C2AEE-1C7D-481C-BBA7-7E507312C53A@employees.org> <e56a6e5b-648d-200e-c35d-97f15a31fb2a@asgard.org> <CAO42Z2zh7fKAgQJq9aLCTiFoSSsTeGM=pK3gXitg+gcxH=9fhQ@mail.gmail.com> <d38857c2-6e92-91d6-bb5d-d3eeeb61276a@gmail.com> <CAO42Z2yb47OyXk__Sz-kO00pfcBJgLAhff5DF=mpAddR0iCnAA@mail.gmail.com> <2612280f-195a-ae7a-b3b1-9022d9282fa7@foobar.org> <56F813F4-C512-40A9-8A68-1090C76A80F6@consulintel.es> <CAHL_VyCN8kU7qnLOphfGR25-xGBe_p6WeGTkKVXwU5uy5aJ8Dg@mail.gmail.com> <65DB4854-97D2-4C31-A691-2CD93812EF93@consulintel.es> <CAHL_VyCMpCcGkEQu+RV1GRf2QLB-HD0+AOOBV0YhfQ5sbydVzQ@mail.gmail.com> <8CE7A0CD-97D9-46A0-814D-CAF8788F9964@consulintel.es> <e3e0bf2273e04f15b792665d0f66dfe5@boeing.com> <4c5fab33-2bff-e5b5-fc1d-8f60a01a146d@go6.si> <b4525832-9151-20bf-7136-31d87ba6c88d@huitema.net> <463f15cf-2754-e2e8-609d-dc0f33448c6c@go6.si> <ff649810-7242-7bc2-d36f-3f998f7bdd71@asgard.org> <9CDF41CA-83B4-4FC4-B995-EF79727C5458@steffann.nl> <CAO42Z2wA+vLmU7+sU6xLK7TO6pWfNQA5shs9zp=PqANCihLmBQ@mail.gmail.com>
To: Mark Smith <markzzzsmith@gmail.com>
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>>> Seems to me several operators have offered their opinions here. If you want more opinions, maybe ask a group of operators?
>> 
>> Not a very helpful comment... I think the underlying problem here is that there is no technical solution available that solves stable IPv6 address delegation at residential scale in an acceptable way.
>> 
>> - For stable address delegation the routing inside the ISP becomes a mess, especially when it can't be guaranteed that a customer consistently ends up at the same BNG.
>> - To keep ISP networks scalable, prefixes are aggregated to (roughly) BNG level, making it impossible to keep prefix delegation stable at the customer's end
>> 
> 
> It's not a hard requirement to aggregate prefixes at the individual
> BNG level, and most ISPs should be running BGP to carry customer
> routes. Obviously BGP to scale to 100s of 1000s of routes because the
> Internet runs with it.
> 
> The minimum PD stability needed for fixed access customers (e.g. ADSL,
> FTTH etc.) is within the pool of BNGs they can attach to upon
> reconnection. So if you need or want to aggregate those routes, you
> place the BGP route aggregation boundary at the boundary of your BNG
> pool, rather than at the individual BNG. You then say to your
> customers that if they physically move their service by e.g. moving
> house, they may not receive the same stable PD prefix again, because
> you're not guaranteeing they will reconnect to the same BNG pool.
> 
> It would however be nice to try to provide the customer with a stable
> prefix on a greater scale than just within the same BNG pool, so you
> could pick greater geographic boundaries for your aggregation points,
> rather than at the boundary of an individual BNG pool. For example,
> here in Australia, I'd try to aim for that boundary to be at each of
> the 7 capital city boundaries, even though I may have multiple PoPs
> within a city, with each PoP containing a number of BNGs in a pool
> (and possibly multiple BNG pools within a PoP). Smaller aggregation
> domains e.g. dividing cities into 4 regions might be necessary
> depending on numbers of subscribers.
> 
> You can still provide a guaranteed static and persistent PD prefix to
> customers that want to pay for it, which means that prefix isn't ever
> aggregated and can follow them regardless of where they geographically
> because you never aggregate that prefix. They're paying for and
> getting more value because they're getting a guarantee.

Indeed. Wonder how these pesky mobile phone operators manage to deliver the same telephone number to a user, for years. Across different providers and contracts.
I can’t think this argument is anything but a strawman.

There’s nothing a bit of regulation can’t fix. :-)

Ole