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

[Timothy Winters <[e-mail]>]

Hi Mark and Ted,

I'll add a line asking for a second IA_PD with a unique IAID when sending
Renew/Rebind messages.

~Tim

On Fri, Aug 9, 2024 at 7:33 AM Ted Lemon <[e-mail]> wrote:

> The point of always asking for a /48 isn’t to signal something to the isp
> other than “give me the biggest prefix you are willing to provide.”  If we
> don’t ask for a /48, we won’t get one.
>
> If we ask for additional prefixes, the customer may just never see a
> problem, so I’m not sure how useful a signal this is, but certainly it will
> tell the isp if there is demand for narrower prefixes, and that isn’t a bad
> thing.
>
> Op vr 9 aug 2024 om 03:30 schreef Mark Smith <[e-mail]>
>
>> Hi,
>>
>> On Fri, 9 Aug 2024, 12:20 Ted Lemon, <[e-mail]> wrote:
>>
>>> What’s the downside?  :)
>>>
>>
>> The concern I have is that I've seen obscure individual customer faults
>> float around inside residential help desks for a number of weeks being
>> looked at by different people, rather than being escalated to network
>> engineering as soon as they should be. Eventually it might get escalated,
>> or the customer leaves through frustration.
>>
>> For ISPs that aren't willing to give out large prefixes e.g., /60s,
>> having the CPE ask for additional PD space when it runs out would at least
>> show up in DHCPv6 PD server logs. That network engineering can directly
>> look for that, and it would be absolute evidence of what problem the
>> individual customer is suffering from. It would also be direct evidence to
>> the ISP that they're not handing out big enough prefixes to customers.
>>
>> If an ISP isn't going to honor an IA_PD request for a /48, which I think
>> would be unlikely for ISPs who aren't already handing out /48s, then I
>> don't think this ID specifying to always ask for /48s is going to achieve
>> anything. It won't signal to network engineering that customers are running
>> out of address space because it will hide that customers are running out.
>>
>> Regards,
>> Mark.
>>
>>
>>
>>> 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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