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

[Soohong Daniel Park <soohong.park@samsung.com>]

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