RE: ULAs [Re: draft-ietf-v6ops-ipv6-cpe-router-03.txt WGLC]

["Dan Wing" <dwing@cisco.com>]

> -----Original Message-----
> From: Brian E Carpenter [mailto:brian.e.carpenter@gmail.com] 
> Sent: Tuesday, January 05, 2010 11:48 AM
> To: Dan Wing
> Cc: 'Fred Baker'; v6ops@ops.ietf.org; kurtis@kurtis.pp.se; 
> rbonica@juniper.net; draft-ietf-v6ops-ipv6-cpe-router@tools.ietf.org
> Subject: ULAs [Re: draft-ietf-v6ops-ipv6-cpe-router-03.txt WGLC]
> 
> On 2010-01-06 08:00, Dan Wing wrote:
> ...
> > Section 3.1 should additionally mention that an end-network
> > IPv4 CPE that incorporates a NAT also incorporates a DHCPv4 
> > server.  The inclusion of a DHCP server in the CPE is implied, 
> > but should be explicitly stated.  The DHCP server in the CPE 
> > allows the in-home network to be self-sufficient (for IP 
> > addressing, if not naming).
> 
> Sure, for IPv4, you need DHCP, but...
> 
> > 
> > This is relevant to IPv6 because, I have been told, ULAs
> > provide a similar "LAN only" address.  This should be
> > mentioned or a pointer to how hosts inside the home should
> > use ULAs mentioned.  We do not want streaming between an
> > in-home NAS and an in-home television to rely on the
> > WAN link's availability.  This is mentioned (insufficiently)
> > in Section 4.2 and some of the L-* requirements.
> 
> I don't understand what you're getting at here. Whether the
> LAN uses a ULA prefix is orthogonal to whether it uses
> DHCPv6.

Agreed; but I didn't say DHCPv6 was needed to assign ULAs (you did).

> It can be set up by RAs and SLAAC (or even manually,
> but that's unlikely).
> 
> I think the L-* requirements for ULAs are necessary and sufficient.

I agree the L-* requirements for ULAs are sufficient.

I am asking for more explanatory text about the value and purpose
of ULAs (or a pointer to such explanatory text), in Section 3.2
"IPv6 end-user network architecture", because Section 3.2's only
mention of ULA is that the CE Router is a "ULA boundary".

We're in WGLC, so my suggested text for Section 3.2 is along
the lines of something like this:

   Unique Local IPv6 Unicast Addresses (ULA) [RFC4193] are used
   by hosts communicating within the End-user Network; this is
   functionally similar to RFC1918 addresses used within an
   IPv4 End-user Network.

and place that sentence immediately prior to the sentence in Section 
3.2 starting with "The IPv6 CE router defaults to acting as 
the demarcation point ...".

> Despite the problems with RFC3484, I think the provision of a ULA
> prefix by the CPE will bring about local streaming automatically.
> That was certainly the intention behind ULAs.

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]").

-d