[v6ops] Re: I-D Action: draft-ietf-v6ops-cpe-lan-pd-03.txt

[Ted Lemon <[e-mail]>]

I think it's fine to try to get more prefixes if you don't get the amount
you asked for the first time, by adding IA_PDs with different IAIDs to
subsequent requests. However, we should always ask for a /48. How does the
CPE router know how many prefixes it will be asked to provide? If the ISP
doesn't want to provide a /48, it will provide a smaller allocation, and
that's perfectly fine.

On Thu, Aug 8, 2024 at 2:23 PM Timothy Winters <[e-mail]> wrote:

> Hi Mark,
>
> On Wed, Aug 7, 2024 at 7:06 PM Mark Smith <[e-mail]> wrote:
>
>> Hi,
>>
>> Apologies for the late comments, I seem to be missing IETF ID
>> announcements and WGLCs (I think trying to read everything out of my
>> Inbox might not be working).
>>
>> I don't think logging a system management error for the below
>> situation is good enough in a residential environment:
>>
>> "LPD-2:
>> The IPv6 CE Router MUST assign a prefix from the delegated prefix as
>> specified by L-2 [RFC7084]. If not enough addresses are available the
>> IPv6 CE Router SHOULD log a system management error."
>>
>> Non-technical residential end-users are very unlikely to look up
>> system error logs if they have a fault, they'll call their ISP's help
>> desk straight away - their ISP is their first port of call for any and
>> all faults that look to be Internet faults.
>>
> In this case I was thinking for the ISP to know that they have routers
> that want to give out IA_PD
> on the LAN and they aren't giving a prefix large enough.
>
> In my experience of residential help desk staff looking up or asking
>> customers to look up system logs for error messages isn't a practice
>> either - and if you look at logs of some of these devices they're very
>> chatty so spotting error messages is time consuming, which is counter
>> to a common helpdesk KPI of customer calls answered per hour.
>>
>> I also think in some cases CPE don't expose system logs - from memory,
>> Google's Nest CE routers don't have a system log available.
>>
> I was thinking about getting system logs from CWMP/USP/NETCONF from the
> ISP.
>
>>
>> It would be better if engineering were somehow directly notified of a
>> customer running out of prefixes and ideally could provide more
>> prefixes automatically. The IA_PD Prefix-Length Hint mechanism would
>> do that.
>>
> I'd had discussions with many ISPs, and only a handful of environments
> with the DHCPv6 server
> honor prefix hints.  Most ISPs for planning purposes have a number and
> that's what they send.
>
>>
>> So I'd suggest updating LPD-2 to:
>>
>> "LPD-2:
>> The IPv6 CE Router MUST assign a prefix from the delegated prefix as
>> specified by L-2 [RFC7084]. If not enough prefixes are available the
>> IPv6 CE Router MUST request the number of required additional
>> prefixes, rounded up to the next shortest prefix length bit boundary,
>> via an additional IA_PD option through the Prefix-Length Hint
>> mechanism [RFC8168]. The second or subsequent IA_PD options are used
>> to avoid a renumbering event where the initial and now too-small
>> Prefix-Delegation prefix would be entirely replaced with a new and
>> single larger Prefix-Delegation prefix. The IPv6 CE Router SHOULD log
>> a system management error."
>>
> For this solution, I have some questions.
>
> Are you proposing that subsequent DHCPv6 messages (Renew, Rebind) ask
> for additional IA_PDs, beyond what is currently leased?
>
> OR are you proposing that the CE Router change what it's asking DHCPv6
> Solicit or Request?
>
>>
>> I'm not entirely convinced that "request the number of required
>> additional prefixes, rounded up to the next shortest prefix length bit
>> boundary" is the right amount of address space the CE should request.
>> Perhaps a simpler mechanism would be to request an additional PD
>> Prefix that is the same size as the initial PD prefix provided by the
>> ISP.
>>
> I like this idea the best.  I think this has the highest chance of
> success, that the DHCPv6 Server is
> configured to give out one size.
>
>>
>> (I understand above is complex to provision and manage on the DHCPv6
>> server side and IPv6 addressing side, however that's the price of
>> treating IPv6 address space as if it was scarce rather than abundant.
>> My advice to residential ISPs is to give out /48s. APNIC had no issues
>> with giving an ISP I worked for a few years ago enough address space
>> for us to give all of our 500K residential customers /48s.)
>>
>> Regards,
>> Mark.
>>
>>
>>
>>
>>
>> On Thu, 8 Aug 2024 at 06:39, <[e-mail]> wrote:
>> >
>> > Internet-Draft draft-ietf-v6ops-cpe-lan-pd-03.txt is now available. It
>> is a
>> > work item of the IPv6 Operations (V6OPS) WG of the IETF.
>> >
>> >    Title:   IPv6 CE Routers LAN Prefix Delegation
>> >    Author:  Timothy Winters
>> >    Name:    draft-ietf-v6ops-cpe-lan-pd-03.txt
>> >    Pages:   7
>> >    Dates:   2024-08-07
>> >
>> > Abstract:
>> >
>> >    This document defines requirements for IPv6 CE Routers to support
>> >    DHCPv6 Prefix Delegation for redistributing any unused prefix(es)
>> >    that were delegated to the IPv6 CE Router.  This document updates RFC
>> >    7084.
>> >
>> > The IETF datatracker status page for this Internet-Draft is:
>> > https://datatracker.ietf.org/doc/draft-ietf-v6ops-cpe-lan-pd/
>> >
>> > There is also an HTMLized version available at:
>> > https://datatracker.ietf.org/doc/html/draft-ietf-v6ops-cpe-lan-pd-03
>> >
>> > A diff from the previous version is available at:
>> >
>> https://author-tools.ietf.org/iddiff?url2=draft-ietf-v6ops-cpe-lan-pd-03
>> >
>> > Internet-Drafts are also available by rsync at:
>> > rsync.ietf.org::internet-drafts
>> >
>> >
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