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

[Mark Smith <[e-mail]>]

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 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.

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.

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."

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 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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