Re: RS sending in draft-ietf-v6ops-ipv6-cpe-router-04

[Philip Homburg <pch-v6ops@u-1.phicoh.com>]

In your letter dated Wed, 28 Apr 2010 07:48:18 +0930 you wrote:
>On Tue, 27 Apr 2010 16:13:29 +0200
>Philip Homburg <pch-v6ops@u-1.phicoh.com> wrote:
>
>> In your letter dated Mon, 26 Apr 2010 16:49:51 +0200 you wrote:
>> >LLs are absolutely needed. DHCPv6 uses them as does ND. Furthermore, in the
>> >CPE draft we support the so called "unnumbered" model, whereby the WAN
>> >interface has NO global IPv6 address.
>> 
>> What's the point of requiring a RS if there is not going to be prefix anyhow
>?
>> 
>> If a router is configured for PD, it may just as well leave out the RS
>> all together.
>> 
>Customers in some markets own their CPE. As an ISP, I don't want them
>to be able to choose to use LLs only on their link, because that link
>is the ISPs to manage and make the choice as to what sort of
>addressing they want to use on it (customers can do what they like on
>their LAN interfaces - that's their network). Disabling RS when
>DHCPv6-PD was enabled would prevent the level of control an ISP needs
>to have to provide a good quaility of service (ever tried to
>ping/traceroute to a remote LL for troubleshooting purposes? And I
>really don't want helpdesk staff constantly logging into edge routers,
>even if it was automated and controlled via scripts - they might decide
>to have fun and DoS it with many, many script execution attempts)

Some ISP do not assign any address to the WAN link and the DHCP-DP RFC prevents
me from assigning a address from the prefix to that link. That annoys me to no
end.

But worse, when every ISP comes up with an arbitrary list of features (and
requirements) it becomes almost impossible to help a random person with his
internet connection.  Oh, you don't have a global IP address on WAN link, is
that normal because the ISP doesn't assign one, or did something go wrong?
Neighbor discovery doesn't work, is that normal because the ISP disabled it,
or is something really broken. You only know if you know the details of 
every ISP.

But more practically speaking, how do you know the global IPv6 address of
your customer? With SLAAC you would have to know the MAC address to even
guess that address. Do you guess it based on the link-local address? Do you
call the customer? What if the customers CPE uses temporary (privacy)
addresses?

If you want that kind of control, why not prohibit customer from using there
own CPEs? Limit official support to just the CPEs supplied by the ISP. There
almost endless list of things random CPEs can do wrong.

With prefix delegation, a router is very likely to have at least one global
address from the delegated prefix.