Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds

"Radu-Adrian Feurdean" <> Wed, 30 October 2019 14:28 UTC

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Date: Wed, 30 Oct 2019 15:27:49 +0100
From: "Radu-Adrian Feurdean" <>
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Subject: Re: [v6ops] SLAAC renum: Problem Statement & Operational workarounds
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On Thu, Oct 24, 2019, at 11:20, Alexandre Petrescu wrote:

> In particular, the home networks scenario is very appropriate.
> First, I must say that the home network that I use uses a fixed /56 
> allocated by my ISP.  In this, the prefix never changes, and it is not 
> obtained by DHCPv6-PD - it is guaranteed by contract signed by hand. 
> Such a case could be mentioned, as not being a problem described in this 
> draft.

If you are talking about residential service (not business/enterprise-class), I would like to know who your service provider is.

> I must say that this kind of software (request a prefix with DHCPv6-PD, 
> form sub-prefixes, and put them in RAs on the other interfaces) does not 
> exist as open source or some other available package.

Dibbler-client does that by default. Once the delegated prefix (shorter than /64) is obtained, a /64 from that prefix is assigned to each interface. With proper radvd.conf configuration (prefix ::/64), RAs will be sent for those prefixes.

A lot (?? most ??) of CPEs implementing DHCPv6-PD client do this in some form or another. Some do this automatically (take prefixes and assign them to interfaces), other need manual configuration (n-th prefix go to interface ZZZ).

> Because of that, I am surprised that you call it 'the most common 
> deployment scenario'.  Is this a scenario that is _expected_ to be 'common'?

"Expected enough" to warrant a device to be disqualified as "CPE that supports IPv6" if it doesn't work this way. In an ISP environment.

> I would like to request addition of two other scenarios:
> - an IoT scenario, in which an IoR Router connects several sensors to 
> the Internet.  For example, an IoT Router is deployed in a box at a 
> traffic lights.  The IoT device is the Traffic Lights Controller 
> connected on Ethernet to the IoT Router.  The IoT Router is connected on 4G.
> - a vehicular networks scenario: the On-Board Unit is deployed in a car. 
>   This OBU has a 4G interface and an Ethernet interface.  There are 
> several computers in the car that need IPv6 addresses.

Like : you have a mobile phone on a network doing IPv6+NAT64, you pout it in tethering/mobile-hotspot mode, and connect several other devices (usually laptops) to that hotspot - they all get IPv6 addresses (in the same single /64 that the phone obtained via SLAAC or something else). It is clear that getting a /56 (even a /60 or /62 would do it) via DHCPv6-PD would be a nicer solution, but when your mobile device runs android....