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

[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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