Subject: FW: new draft on IPv6 CPE router available for review

From: "Wes Beebee (wbeebee)" <[email-masked]>
Date: Tue, 1 Jul 2008 13:47:04 -0400

For some reason, Hemant is unable to post to v6ops even though he is subscribed to it.  Therefore, I'm forwarding this e-mail.

- Wes 

-----Original Message-----
From: Hemant Singh (shemant)
Sent: Tuesday, July 01, 2008 11:38 AM
To: 'Remi Denis-Courmont'; Wes Beebee (wbeebee)
Cc: [email-masked]
Subject: RE: new draft on IPv6 CPE router available for review

Remi,

We missed seeing RFC4605 - thanks for its reference. We can shorten section 6.1 to be very brief showing how RFC4605 will work between the WAN and LAN interface(s). Further, right now we don't have strong language in the draft for prefix sub-delegation, but we can consider making it so for prefix sub-delegation - our preference is prefix sub-delegation. 

As for mcast, the CPE router maintains a Mcast Forwarding Information Base (MFIB) that maps mcast group memberships to output LAN interface(s). When a mcast packet on the CPE router downstream needs forwarding from WAN interface to a LAN interface, the MFIB is looked up for packet forwarding. Details on how the MFIB is populated are given in the mcast section. Maybe we can add a picture showing CPE router conceptual blocks for mcast and also demonstrate mcast forwarding with an example if more folks don't understand this section.

We do have v6-to-v4 and v4-to-v6 NAT in mind even though we haven't added it to the CPE router draft. We didn't write those sections yet because some functionality spans the CPE router IPv4 features when our draft currently says any IPv4 feature is out of scope for the document. We have to massage some text in the document and then write a NAT section. We don't plan on recommending any v6-to-v6 NAT for the CPE router since IPv6 standards also do not recommend it.

Thanks.

Hemant & Wes

-----Original Message-----
From: Remi Denis-Courmont [mailto:[email-masked]]
Sent: Tuesday, July 01, 2008 5:37 AM
To: Wes Beebee (wbeebee)
Cc: [email-masked]; Hemant Singh (shemant)
Subject: Re: new draft on IPv6 CPE router available for review

On Mon, 30 Jun 2008 13:14:22 -0400, "Wes Beebee (wbeebee)"

<[email-masked]> wrote:

> Please review this draft.

> http://www.ietf.org/internet-drafts/draft-wbeebee-ipv6-cpe-router-00.t
> xt

Section 6.1 seems to be a reinvention of RFC4605. I am also confused as to

how multicast should be forwarded (or not) between the multiple LAN

interfaces, if there are more than one.

Also, IMHO, the document lacks (adequate) guidance on the chaining of CPEs.

This is a real life problem, which in IPv4 is typically "solved" through

layering of NATs. It might not be wise to ignore the issue in IPv6. I guess

one solution is to have the CPE revert to bridging (but loops may occur),

while another solution is to _mandate_ support for prefix sub-delegation.

-- 

Rémi Denis-Courmont

http://www.remlab.net

---

From: "Wes Beebee (wbeebee)" <[email-masked]>
Date: Tue, 1 Jul 2008 15:53:44 -0400

Forwarding for Hemant to continue the discussion...

- Wes

-----Original Message-----
From: Hemant Singh (shemant)
Sent: Tuesday, July 01, 2008 3:20 PM
To: 'Shin Miyakawa'; [email-masked]
Cc: [email-masked]; Wes Beebee (wbeebee); [email-masked];
[email-masked]; [email-masked]; Hemant Singh (shemant)
Subject: RE: new draft on IPv6 CPE router available for review

Shin,

Thanks for your comments. We agree with (A) below. As for (B), we leave
it to the mailer to decide if it's a MUST for the CPE router to support
the link-local only WAN model or the MUST can be a MAY. As we said to
Mikael's review yesterday, we see no technical problems with the CPE
router supporting the link-local only WAN model. Of course, we totally
want the first model to be a MUST for the CPE router to support - in
this model the WAN interface acquires a global IPv6 address.

Hemant & Wes.

-----Original Message-----
From: Shin Miyakawa [mailto:[email-masked]]
Sent: Tuesday, July 01, 2008 3:11 PM
To: [email-masked]
Cc: [email-masked]; Wes Beebee (wbeebee); Hemant Singh (shemant);
[email-masked]; [email-masked]; [email-masked];
[email-masked]
Subject: Re: new draft on IPv6 CPE router available for review

Hello, David :-)

> I would add my support to Mikael's request that the draft has the 
> option of having a global unicast WAN address OR having link-local 
> only WAN on a routing CPE. Would it be okay to incorporate the content

> of Shin's draft into the CPE discussion/draft?

David, as we have discussed this several months off from this mailing
list in various places on the Earth, you know the reason why I said.

Then.... "OR" means sometime ambiguous.......

Actually, my opinion is

(A) the draft should have "discussions" text to explain why those are
recommended
    and this draft should be more generalized not only for cable TV
systems.

    For example, section 1 in this draft's clearly said that
    "WAN interface is Ethernet encapsulated", but it should be converted
to
    "WAN interface may be Ethernet encapsulated but not limited too" 
    or something like that because we need to think about other
semantics like PPP.

(B) Because a strong host model is one of possible implemenation of CPE,
so

    "Global unicast WAN address" MUST be supported
       and                       ^^^^
    "Link-Local only WAN on a routing CPE" MAY be supported

as the "access concentrator"'s specification which provides the service
to the IPv6 CPE.

Best wishes,

Shin Miyakawa

P.S.

However I also prefer Mikael's model personally, we have to be very
realistic and tolerant to any implemenations compatible with the
standard.