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Re: ULAs [Re: draft-ietf-v6ops-ipv6-cpe-router-03.txt WGLC]
On Tue, 5 Jan 2010 15:37:52 -0600
"Hemant Singh (shemant)" <shemant@cisco.com> wrote:
>
> >-----Original Message-----
> >From: Dan Wing (dwing)
> >Sent: Tuesday, January 05, 2010 3:16 PM
> >To: 'Brian E Carpenter'
> >Cc: Fred Baker (fred); v6ops@ops.ietf.org; kurtis@kurtis.pp.se;
> rbonica@juniper.net; draft-ietf-v6ops-ipv6-cpe-router@tools.ietf.org
> >Subject: RE: ULAs [Re: draft-ietf-v6ops-ipv6-cpe-router-03.txt WGLC]
>
> >I'm asking for text to provide motivation for the existing L-1
> >requirement (which reads "The IPv6 CE router MUST support ULA
> >addressing [RFC4193]").
>
> About two years back Brian Carpenter gave the dentist's office as one
> motivation for use of ULA in the home with the CE Rtr. The dentist's
> office network is setup once and that's how it runs for a long time. If
> the Internet WAN link of the dentist's office CE Rtr goes down, the
> dentist can still print from his office PC to his printer which are both
> using ULA. The other motivation that is also in emails of v6ops
> archives is that what does one do for configuration of the CE Rtr right
> out of shrink-wrap? The user bought the device from retail and powered
> it up in the home before attaching the CE Router to any WAN. Without a
> GUA (Globally Unique Address), how does one configure the CE Rtr if
> using link-local is spotty at best to access a device with a link-local
> URL. You see, the link-local can be common to all LAN ports of the CE
> Rtr and that is why it's not a good address to use to configure the CE
> Rtr in a web browser. So that leaves only the GUA (auto-configured on
> the CE Rtr on power up) to configure the device with using a web
> browser. Auto-configuration of the CE Rtr is part of the Phase II
> document, so any more details in the current CE Rtr doc (Phase I) will
> be skipped.
Somewhat related, is there room in this ID for adding Zerconf/multicast
DNS etc. for the convenience of browsing or device name based discovery
to be able to configure the device via a web/ software application
interface? ULAs are great for this purpose, but end-users should never
have to work out what they are type them into anywhere, and I think
there should be a standard mechanism to discover CPE configuration
interfaces. Or is it out of scope?
Regards,
Mark.
>
> If none objects that motivation for use of ULA needs to be included as
> text in the CE Rtr doc, what we can do is work on a formal version of
> what I have summarized above.
>
> Further, in an earlier version of the CE Rtr we also said the ULA and
> the GUA coexist on a LAN network interface. Since the addresses
> coexist, here is what our earlier version said about RFC 3484.
>
> "... every LAN interface has a link-local unicast address, a ULA, and a
> GUA. Therefore, the interface has to apply source address selection to
> determine which address to use as a source for outgoing packets. Since
> the GUA and ULA have a larger scope than the link-local address (rule #2
> of [RFC3484]), the GUA or ULA will be used as a source address of
> outgoing packets that are not subject to rule #1. For source address
> selection between a GUA and ULA, rule #8 of [RFC3484] will be used."
>
> In the -03 version we have removed such text.
>
> Thanks,
>
> Hemant
>