RE: Comments on draft-wbeebee-ipv6-cpe-router-01.txt

["Hemant Singh (shemant)" <shemant@cisco.com>]

BTW, we have already replied to Barabara on July 8th that unnumbered
model that she proposed by giving global IPv6 addresses to LAN
interface(s) and only a link-local to WAN interface(s) is fine for the
CPE Router. See the email exchange below. I was just warning today that
for routing functionality, we just need a global IPv6 address on the WAN
interface. After all, the CPE Router is a router.

3. I disagree with the behavior suggested for "unnumbered" model. I
don't think a CPE router should automatically open up a maintenance
loopback interface just because it doesn't get a global IP address. If
this is a retail CPE router, I think it really shouldn't be setting up a
maintenance loopback interface by default. Our access network is
definitely considering not giving out global addresses to the WAN
interface, but we have no requirements for any "loopback" maintenance
interfaces at all. We have considered the possibility of a separate IP
address for our TR-069 management of the CPE routers that we supply, but
would want this to be a configurable option. As a default, we believe
that the global address that the CPE router selects for its LAN
interface is sufficient for all WAN-side Internet communication,
including VoIP, TR-069, ping, traceroute, etc. [I often do ping tests
from the router when my WAN is having problems].

<hs>No problem. So if the SP is not doling out an IPv6 address to the
WAN interface, is the SP doling out an IA_PD option to the CPE Router?
If yes, then when global IPv6 addresses from the IA_PD get assigned to
the LAN interface(s) of the CPE Router, one can always use one more
global address to configure on the WAN interface. However, if an SP does
not like assigning of a global IPv6 address to the WAN interface, that's
is fine with he CPE Router for PPP. Further, if the SP does not dole out
an IA_PD but assigns one IPv6 global address to the LAN interface(s),
that's a model the CPE Router also does not have a problem with
supporting for PPP. However, for non-PPP cases, the CPE Router will need
a global IPv6 address on the WAN interface and the WAN prefix must be
different from the LAN prefixes because the WAN and LAN interface(s) are
two separate routing domains of the CPE Router. We have received
feedback from you (AT&T), NTT (Japan), and some folks in Europe. We will
work on the text of our document to be general enough that we satisfy
all folks.
</hs>

However, we didn't still not make any change in our -02 draft for
Loopback interface because we want to first see if a common model for
the CPE Router can be found between AT&T, NTT, and other European DSL
folks. 

Hemant

-----Original Message-----
From: ichiroumakino@gmail.com [mailto:ichiroumakino@gmail.com] On Behalf
Of Ole Troan
Sent: Tuesday, July 15, 2008 6:56 PM
To: Stark, Barbara
Cc: Hemant Singh (shemant); v6ops@ops.ietf.org; Antonio Querubin
Subject: Re: Comments on draft-wbeebee-ipv6-cpe-router-01.txt

Barbara,

> I disagree that if the loopback interface is not configured "you will 
> have to use the Numbered model of our document and assign a global 
> IPV6 to the WAN interface". Just to be sure, I think you're saying 
> that the CPE router will need to get a global IPv6 address via SLAAC 
> or stateful DHCPv6, from the access network. I do not see any reason 
> why the CPE router cannot use one of the addresses from its assigned 
> prefix. Since we are definitely considering using the "unnumbered 
> model", and we have no loopback interface in our devices (and have no 
> intention of having them), I think I'm going to have to try to get a
second opinion on this.
> Does anyone else have an opinion on whether or not the "unnumbered 
> model" will only work in the presence of a loopback interface?
>
> By the way, I've never seen such a loopback interface in any mass 
> market retail CPE routers. To me, the capabilities found in such mass 
> market routers should be the benchmark for "very normal". I'm also not

> familiar with it in DSL routers. DSL routers are also "very normal",
worldwide.
> I've been trying to search the Internet for products that include this

> interface, and all I can find are Cisco products with IOS. I'm curious

> as to whether any other vendors implement this interface, and, if so, 
> on what sorts of mass market products.

the loopback interface is a red herring. the unnumbered model will work
just fine without it.

/ot