Re: [dhcwg] IEEE 802.11ai and DHCP

Le 12/02/2013 21:25, Hiroki Nakano a écrit :
> Dear all,
>
> I'm participating in IEEE 802.11 WG TGai task group which is for
> FILS (Fast Initiali Link Setup). They are working for speeding up of
> 802.11 process and trying to provide a new framework for higher
> layer protocols.
>
> I'd like to introduce the overview of prospective 802.11ai
> specification and discuss usages of DHCP on it with DHC WG people in
> March. The followings are a brief introduction.
>
> TGai supposes Wireless LAN is used in very crowded envirionment such
> as railway stations in a giant metropolis. TGai also supposes moving
> hosts through the front of Access Points. In these cases, it is
> effective to reduce management frames of 802.11, especially frames
> for probing APs, authentication and association. The current
> framework takes a few seconds to set up network connectivity before
> starting to communicate. The target of TGai is under one second.
>
> TGai is trying to reduce management frames of 802.11 itself, and in
> addition provide framework for higher layers such as IP to send and
> receive packets during 802.11 association process. The currently
> proposed framework provides "ONE round-trip packet exchange" by
> piggybacking on 802.11 Association Request/Response frames.
>
> My interest is how to fit DHCP to this framework. In case of DHCPv4,
> this is achieved by using Rapid Commit Option (RFC4039) and making
> some additional and trivial rules. In case of DHCPv6, we have to use
> both RA and DHCPv6. In addition, DAD and randomly generated
> addresses have to be considered. Share your idea, please.

For DHCPv6 - it is possible to use a DHCPv6 single roundtrip to realize
complete configuration to the Client (IPv6 address, default route, DNS
resolver address).

The straightforward means to achieve complete configuration is to use RA
_and_ DHCP (because only RA provides the default route), for a total of
6 messages .

But the better means (single DHCPv6 roundtrip - 2 messages) is to use
DHCPv6 to configure the default route as well, and not use RA:
draft-ietf-mif-dhcpv6-route-option-05 "DHCPv6 Route Options" and
draft-mouton-mif-dhcpv6-drlo-02.txt "Default Router List Option for
DHCPv6 (DRLO)"

Alternatively, use RS/RA single exchange (and not DHCPv6), with DNS
resolver address:
RFC6106 "IPv6 Router Advertisement Options for DNS Configuration"

DAD and MLD are two other protocols which may get in the way to fast
exchanges.  They could be avoided with proper tweaking of specification
and implementation.

> 802.11 TGai is still going on and its specification is subject to
> change, but I'd like to discuss in IETF DHCP issues related to
> 802.11ai and arrange I-D according to the progress of TGai task
> group.

I think it is indeed a good point to discuss such an I-D.

Alex

>
> Regards,
>
> Hiroki Nakano Trans New Technology, Inc. <cas@trans-nt.com>
>
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