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

[Ted Lemon <[e-mail]>]

What’s the downside?  :)

Op do 8 aug 2024 om 14:36 schreef Timothy Winters <[e-mail]>

> Ted,
>
> On Thu, Aug 8, 2024 at 2:28 PM Ted Lemon <[e-mail]> wrote:
>
>> 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.
>>
> I was toying with that idea as well.  Just asking for /48.
>
>>
>> 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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