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

[Timothy Winters <[e-mail]>]

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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