Subject: RE: updates to IPv6 over PPP spec.

From: "Karim El-Malki (HF/EAB)" <[email-masked]>
Date: Wed, 11 Feb 2004 22:41:39 +0100

> (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.

(a) doesn't seem correct to me. In terms of 3GPP nets the host is
stationary with respect to its default router. Also as recommended
in RFC 3314 an entire /64 is assigned to a mobile's connection so DAD
is not useful. Looks to me like the 3GPP case would actually be in
favour of disabling DAD.

/Karim

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From: "Barany, Pete" <[email-masked]>
Date: Thu, 12 Feb 2004 07:45:52 -0800

The PDSN in cdma2000 does not have a global unicast address for the PPP
connection between itself and the mobile. It only has a link-local
address. The mobile has both a link-local and global unicast address.

Pete

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of
Pekka Savola
Sent: Wednesday, February 11, 2004 8:15 PM
To: Barany, Pete
Cc: Karim El-Malki (HF/EAB); [email-masked]
Subject: RE: updates to IPv6 over PPP spec.

On Wed, 11 Feb 2004, Barany, Pete wrote:
> The rationale also fails to account for 3GPP2 networks (cdma2000).
Here,
> PPP (IPV6CP) is used to obtain an IPv6 address for the mobile (or the
> MIPv6 CoA for the mobile). UMTS uses a PDP context instead.
> 
> Since 3GPP2 has mandated a restriction that the /64 prefix advertised
to
> a mobile by a PDSN (similar to 'GGSN' if you are a UMTS-only person)
be
> unique/exclusive to that PPP link, then there is no need for the
> suggested update #1 below. In fact, quite the contrary.

Umm.. but doesn't the access router which terminates the PPP link also
have an address from that /64 prefix (e.g., ::1) -- or does it have a
link-local address only?

In case such an assumption is made, it should be spelled out clearly 
enough.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

---

From: "Barany, Pete" <[email-masked]>
Date: Fri, 13 Feb 2004 07:42:54 -0800

Agreed. I can take a stab at writing some text and forward it to the
editor off-line. I wouldn't imagine that it would be more than a few
sentences/one or two paragraphs. Thanks.

-Pete

-----Original Message-----
From: Pekka Savola [mailto:[email-masked]] 
Sent: Thursday, February 12, 2004 10:33 PM
To: Barany, Pete
Cc: [email-masked]
Subject: Re: FW: updates to IPv6 over PPP spec.

On Thu, 12 Feb 2004, Barany, Pete wrote:
> I forgot to mention where this is explicitly stated. In TIA-835-C,
> Section 3.2.1.4.2 "IPv6 Addressing":
> 
> --->BEGIN
> For an IPv6 MS, the PDSN shall be the default router and the PPP
> termination point. The PDSN shall allocate one globally unique /64
> prefix to each PPP link. The PDSN shall not construct any global
address
> from this prefix.
> --->END

Right -- but as PPPv6 is used in other scopes than 3GPP and 3GPP2 as 
well, PPP specification should probably include some discussion of the 
assumptions required for disabling DAD.

> From: Barany, Pete 
> Sent: Thursday, February 12, 2004 7:46 AM
> To: 'Pekka Savola'