RE: [802.21] Comments on 21-06-0698-01-0000_IP_configuration_methods_IE.doc
Daniel,
>IP_Configuration_Method IE aims to reduce the delay caused by *a small
number of RA*.
Are we solving the problem of minimizing the delay when is no RA in
reponse? My understanding is that this happens only when there is no
router on the link to provide a RA (/in response to RS).
> Does it makes sense ?
I am not sure if this is an issue for the managed radio links we are
discussing here.
Regards,
Srini
-----Original Message-----
From: ext Soohong Daniel Park [mailto:soohong.park@SAMSUNG.COM]
Sent: Monday, August 07, 2006 5:15 AM
To: STDS-802-21@listserv.ieee.org
Subject: Re: [802.21] Comments on
21-06-0698-01-0000_IP_configuration_methods_IE.doc
Hi Yoshi,
>> >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?
Look at the Figure 1 of 21 specification. MIH Function can trigger upper
layers using Event Service and DHCP belongs to upper layers. Once
detecting a link, this hint goes to the upper layer via MIH Function.
Then, DHCP Solicit message is sent by a mobile station before runing
RS/RA procedure.
>>
>> >
>> >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?
Well, what I tried to explain above was for IPv6 address configuration
procedure without 21 support. In that case, we can't run them in
parallel. But, MIH Function can toss a relevant hint generated by lower
layer to the upper layer.
and DHCP works accordingly.
There is no violation against IETF standard. If a link has no routers
(RA support), host use the DHCPv6 to obtain addresses after having sent
a small number of RS as described in RFC2461. IP_Configuration_Method IE
aims to reduce the delay caused by *a small number of RA*.
Does it makes sense ?
Regards,
Daniel