Subject: Re: updates to IPv6 over PPP spec.

From: srihari varada <[email-masked]>
Date: Wed, 11 Feb 2004 16:17:27 -0500

Dear All:

As broadcasted on the IPv6 and PPPext mailing lists some time back, we 
are soliciting input to update the RFC 2472. Provided below is the input 
received so far from the IPv6 community on the IPv6 over PPP spec. 
Please review and make any additions to the list at your earliest 
convenience. If no further input is received in the next few days or so, 
consensus is assumed and edits to the spec. would be initiated.

(1) The Duplicate address detection shouldn’t be recommended to be 
disabled, if the IPv6CP negotiates interface identifier with the peer.
*
*

    *Rationale:*

    (a) In the mobile (3GPP) networks the host isn't stationary. As
    such, the interface identifier uniqueness may not be ensured at
    different space points in the provider network (for instance, in the
    case of randomly generated Interface Identifier). This would then
    warrant the mobile host to trigger duplicate address detection as
    and when it changes it's position.

    (b) RFC 2462, section 5.4 states that if there is a group of
    addresses that are generated from a given interface identifier, the
    Link-Local address MUST at least be tested for uniqueness. It is
    likely that an interface would have multiple addresses (Link Local,
    site-local and global scope addresses, for instance). This would
    then necessitates the Link-Local address to be tested for
    uniqueness. Thus, the text needs to be changed for consistency
    reasons."

2. Update the reference section with corrected URL to guidelines for 
EUI-64 assignment. Alternatively, remove the URL altogether, but keep 
the reference identifying IEEE.org as the source.

3. Review and clarify the IPv6 over PPP specification to match the 
current IPv6 addressing architecture. (as stated in RFC 3314)

4. RA (Route Advertisement) should be mentioned somewhere in the
Document for global unicast address configuration and other 
configuration parameters. In IPCP, the IP address is part of the IPCP. 
But in IPv6CP, only the interface ID is negotiated and link local is 
auto-configured. For a new comer, it took us a while to figure out that 
RA is used to configure the rest of stuff.

5. Default ordering of IPv6CP and IPCP negotiation in a dual stack mode 
should be explained -- RFC 1661 says that there could be one or more 
NCPs in one PPP link. During inter-operability testing, we found some 
vendors started NCP with IPv6CP and others with IPCP. It will evetually 
work. But some extra messages will be dropped because of miss match. It 
will be good to document the relationship between IPv6CP and IPCP in a 
dual stack mode. Of course, the order should be configurable by the user 
and one of them may be disabled in a single stack mode (either IPv4 only 
or IPv6 only).

6. The Interface Identifier section should mention an exception (due to 
the need for privary addresses) to the suggestion of consistent 
reproduction of the interface identifier -- RFC 2472 states that the 
interface identifier is suggested to be consistently reproducable across 
initializations of the IPv6CP finite state machine (see section 4.1). 
The text should be elaborated to include an exception as identified by 
the Privacy Extensions for Stateless Address Autoconfiguration in IPv6 
(RFC 3041).

Regards,

Srihari Varada

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---

From: Francis Dupont <[email-masked]>
Date: Wed, 11 Feb 2004 22:57:03 +0100

In your previous mail you wrote:

=> as I have no concern about (1) I disagree with the rationale.

       *Rationale:*

=> this makes sense if and only if you suggest that a 3GPP terminal
can change its PPP peer without shutting down PPP???

=> we agreed in the WG that DAD is really per address and not per
interface ID so MUST be done for every addresses (perhaps at the
exception of the link-local using the negociated IID).

=> I disagree, this implies the PPP link is between an host and a router
when two other cases are possible.

=> this is not in the scope of the WG: if some implementations don't support
parallel NCPs either they need to be fixed or the PPP specifications should
forbid this.

=> I am not convinced this is really useful because the IID can be used
only for the link-local address which is not supposed to leak outside
the link...

Regards

[email-masked]

PS: BTW I haven't seen a call for the agenda?

---

From: "Anil Kumar Reddy" <[email-masked]>
Date: Mon, 16 Feb 2004 12:20:00 +0530

:
: 4. RA (Route Advertisement) should be mentioned somewhere in 
: the Document for global unicast address configuration and other 
: configuration parameters. In IPCP, the IP address is part of 
: the IPCP. 
: But in IPv6CP, only the interface ID is negotiated and link local is 
: auto-configured. For a new comer, it took us a while to 
: figure out that 
: RA is used to configure the rest of stuff.
:

	Yes, we should provide a generic statement on obtaining
	global unicast address using either stateless (RA) or stateful
	(DHCPv6) auto-configuration and mention that it is out of 
	ppp scope.