-----Original Message-----
From: Ralph Droms (rdroms)
Sent: Monday, July 21, 2008 11:21 AM
To: Rémi Denis-Courmont
Cc: Ralph Droms (rdroms); Alain Durand; Hemant Singh (shemant);
v6ops@ops.ietf.org ; Wes Beebee (wbeebee)
Subject: Re: New (-02) version of IPv6 CPE Router draft is available
for review
The only time the CPE router needs to use GUA is if it has never
received a delegated prefix.
Huh? Did you mean to say ULA? Anyhow, the rest of your discussion
does not map to the problem at hand. Our problem is that I have
bought this standalone CPE router from Best Buy (in the U.S.) and
now I want to configure it at home via the web for the first time.
I have still not connected the router to the SP WAN. I just connect
an Ethernet cable between the CPE Router LAN interface and my PC and
power up the router. Now I need to configure the router via the web.
Initially we had suggested to use link-local address of the LAN
interface to access the router from the web. But Remi said that
needs
the full network name interface configuration in some browsers (we
didn't need that in our test at Cisco) and also the access has
some non-compliance with HTTP. So then we said, we'll use a ULA.
At this juncture of the router operation/configuration, the router
doesn't have any GUA. A lot of folks in private emails to us have
agreed to supporting ULA on the LAN interface(s) of the CPE Router.
We really don't think a coexisting ULA with GUA on the LAN in a
problem for any data forwarding or source address selection.
We have one solution using ULA. If a better solution is available
for
the problem described above, we are open to it.
Thanks.
Hemant
Prefix delegation uses the same leasing mechanism as address
assignment; if the WAN interface on the CPE router is not up, the
CPE
router can still use > the previously delegated prefix on the
subscriber network.
So, as long as the CPE router has been connected to the ISP network
at least once and has obtained a delegated prefix, there is no need
for GUA. To avoid unnecessary complexity, I would strongly
recommend
that the CPE router be required to complete an initial prefix
delegation operation when first
connected to the ISP before enabling any downstream interfaces.
Once that prefix delegation takes place, it is immaterial whether
the
LAN or WAN interface comes up first.
This discussion brings up the problem of subscriber network
operation
- is it an explicit goal of this document that the subscriber
network be able to operate even if the WAN interface is not up?
What are the expectations > for that unconnected operation and what
services must the CPE router provide to meet those expectations?
According to the spec, the requesting router can only use the
delegated prefix until the lease on the prefix expires. We hadn't
thought about relaxing > that restriction to allow the requesting
router to continue to use the delegated prefix until it has a WAN
connection back to the delegating router.
- Ralph
On Jul 21, 2008, at Jul 21, 2008,10:57 AM, Rémi Denis-Courmont wrote:
Le vendredi 18 juillet 2008 19:25:54 Alain Durand, vous avez écrit :
Supporting both ULA & GUA at the same time is also a source of
complexity and confusion. The key problem I see is with external
referrals in multi-party communications where some of the hosts are
inside, and some are outside. Mixing ULA & GUA can have complex
consequences, and again generates service call.
Yeah. Broken RFC3484 implementations will do just that. But all
nodes
(broken and non-broken RFC3484 implementations alike) will *break*
without ULA, until we have *instantaneous* 100%-reliable and
100%-available upstream connections (which we will NEVER have).
Without this, the network will simply not work until the ISP
connection is established (if ever), which is a total non-starter.
Therefore, it seems like a total non-question that ULA is the way to
go.
Also, if I read the text correctly, if the WAN interface gets
configured first, no ULA are generated. Which leads to confusing
situation depending on whether the customer turns its modem on
before or after its CPE.
You may have a point here.
I would rather like the text to recommend to only use ULA when
nothing else is available and immediately renumber to GUA when
those
are acquired.
And break existing connections on the local network? Total no go.
--
Rémi Denis-Courmont
http://www.remlab.net/