Re: [802.21] Comments on 21-06-0698-01-0000_IP_configuration_methods_IE.doc
Hi Daniel,
On Sat, Aug 05, 2006 at 09:31:11PM +0900, Soohong Daniel Park wrote:
(snip)
> >
> >First, it is not clear whether it is allowed to run DHCPv6 before
> >running router discovery.
>
> I don't think we need a deep implication regarding the proposed IE
> since it is a simple hint to support more efficient mobility than now.
I agree that the information should be just a hint, but I need several
compelling use cases to agree.
> Anyway, it is most likely L2 trigger concept (especially Link UP) that
> can trigger upper layer (IP layer) operation before completing its own
> L2 operation. This benefit is an explicit consensus in IETF and
> world-wide deployment now in mobile environment. That can reduce
> reduncent delays sort of caused by hierarchical host operations
> (L1->L2->L3->upper layers). Given this utility, the mobile station can
> run its IP operation in parallel while L2 attachment. Likewise, 802.21
> can trigger DHCPv6 before runing router discovery based on 802.21
> conceptual model (especially Event Service).
How can 802.21 trigger DHCPv6 before runing router discovery, while
your comment below indicates that router discovery is needed before
running DHCPv6?
>
> >
> >Second, if it is allowed to run DHCPv6 before running router
> >discovery, then it should be possible to run DHCPv6 and router
> >discovery in parallel regardless of the use of proposed IE or even
> >regardless of the use of 802.21.
>
> No, To run DHCPv6 on the host, it should get a related information
> from router (Router Advertisement [Managed flag] = set), then the
> mobile station can start sending DHCPv6 Solicit message. If no RA
> (host timeout), the mobile station can also start initiating DHCPv6
> operation. From the real experience, it spends at lease a couple of
> seconds or more. Yes, it is an existing limitation from the IETF
> perspective, but we can live with 802.21, and I don't see any trouble
> to make use of the facilities of 802.21 to resolve those limitations.
If IETF does not allow parallel runs of DHCPv6 and router discovery
how can 802.21 resolve the limitations without violating IETF
protocols?
Regards,
Yoshihiro Ohba
>
> >The only benefit to use the proposed
> >IE would be to avoid running DHCPv6 when DHCPv6 is not used at all for
> >configuring IP address and other information, but I think DHCPv6 is
> >used in most deployment at least for configuring other information.
>
> It is also required the host to get a related information from the
> router (Router Advertisement [Other flag] = set). Host timeout is
> applied for this case too. But, it is not a critical part from the
> handover perspective since other information will take place after
> completing IP configuration. So, it is not scope of 21.
>
> >So the benefit of the IP_Configuration_Methods_IE is still not clear
> >to me.
>
> I hope the mentions above help. Further details are highly welcome.
>
> --
>
>
> Daniel (Soohong Daniel Park)
> Mobile Convergence Laboratory, SAMSUNG Electronics.
>