Re: [DNA-BOF] [Question]Movement Detection and DAD in MIPv6-24

[Vijay Devarapalli <vijayd@iprg.nokia.com>]

lookup the DAD vs DIID discussion on the IPv6 mailing
list sometime back.

some implementations (KAME being one) do DAD for every
address, even if they are configured from the same
interface ID. some implementations take advantage of
the optimization in RFC 2462.

Vijay

Soohong Daniel Park wrote:
> 
> Hi
> 
> I am sorry if I am missing previous discussion in mobileip WG.
> 
> MIPv6 draft-24 said:
> 
> 11.5.1 Movement Detection
> ...
> When the mobile node detects an L3 handover, it performs Duplicate
> Address Detection [13] on its link-local address, selects a new
> default router as a consequence of Router Discovery, and then
> performs Prefix Discovery with that new router to form new care-of
> address(es) as described in Section 11.5.2.
> 
> 11.5.2 Forming New Care-of Addresses
> RFC 2462 [13] specifies that in normal processing for Duplicate
> Address Detection, the node SHOULD delay sending the initial Neighbor
> Solicitation message by a random delay between 0 and
> MAX_RTR_SOLICITATION_DELAY.  Since delaying DAD can result in
> significant delays in configuring a new care-of address when the
> Mobile Node moves to a new link, the Mobile Node preferably SHOULD
> NOT delay DAD when configuring a new care-of address.
> 
> After reading above both, I can figure out below procedure.
> 
> 1)Detecting L3 handover on MN
> 2)Performing DAD for LLA
> 3)Performing RD
> 4)Obtaining Prefix and infos
> 5)Configuring a new CoA
> 6)Performing DAD for CoA (possibly without random delay)
> 7)Performing BU
> 
> I am just wondering why DAD is performned in twice.
> 
> RFC 2462 recommended:
> Thus, for a set of addresses formed from the same
> interface identifier, it is sufficient to check that the link-
> local address generated from the identifier is unique on the
> link. In such cases, the link-local address MUST be tested for
> uniqueness, and if no duplicate address is detected, an
> implementation MAY choose to skip Duplicate Address Detection
> for additional addresses derived from the same interface
> identifier.
> 
> Generally,both LLA and CoA on the MN are composed of the same identifier
> 
> Am I missing something ?
> 
> Daniel (Soohong Daniel Park)
> Mobile Platform Laboratory, SAMSUNG Electronics