Subject: RE: DAD in node requirements draft

From: "Peter Barany" <[email-masked]>
Date: Tue, 25 Mar 2003 13:12:16 -0600

Hi,

Right, there are always privacy address extensions ((RFC 3041).

But the original question related to PPP links.

During 3GPP (UMTS) work on PDP context activation, it was agreed to make the
/64 prefix unique per primary (and associated secondary) PDP contexts so
that DAD would not have to be performed (particularly since privacy
addresses are specified for use in 3GPP). See RFC 3314 and, I believe, 3G TS
23.060 (and/or maybe another document in the 3GPP 24 series).

3GPP2 (cdma2000) uses PPP and not a PDP context. In IS-835-B it is stated
that the /64 prefix(es) must be unique to that PPP link ... again avoiding
DAD when privacy addresses are used.

Since the IETF IPv6 WG is in the process of updating the IPv6 PPP RFC 2472
(more specifically IPV6CP), my question is: What changes are being planned
to that RFC? Do any of these changes pertain to the granularity/uniqueness
of the /64 prefix? Thanks.

Regards,

Pete

-----Original Message-----
From: Ole Troan [mailto:[email-masked]]
Sent: Tuesday, March 25, 2003 12:56 PM
To: Mika Liljeberg
Cc: [email-masked]; [email-masked]; [email-masked]
Subject: Re: DAD in node requirements draft

Mika,

>> 	it makes more sense when rules are simpler.  if you always perform
DAD
>> 	you can always ensure there's no duplicate.  even if machine A is
>> 	autoconfigured with prefix P::/64 and DAD-safe link-local address
>> 	fe80::ID, the other end could configure P:ID intentionally.
>
> It would be more efficient to always do DAD with the link-local prefix
> rather than full address, and just ensure that each IID is owned by a
> single machine. I.e., if you configure P:ID, do dad with FE80:ID (unless
> already done) and defend all X:ID.

sure, but that wouldn't allow different nodes using the same IID with
different prefix. note the mechanism is called DAD not DIID. this has
been discussed to death numerous times, please refer to the archive.

/ot
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From: Ole Troan <[email-masked]>
Date: Tue, 25 Mar 2003 19:29:14 +0000

[...]

> DAD when privacy addresses are used.

requiring that a /64 is unique on a link does not avoid DAD.
doesn't the 3GPP specs restrict one end of the link to not use any
addresses from the prefix, if so DAD is not needed.

> of the /64 prefix? Thanks.

the only thing I can see requiring an update is that the value of
DupAddrDetectTransmits should default to 1 not 0.

you can turn off DAD in your environment if you know you don't need
it.

/ot