Re: [dhcwg] Gen-ART review of draft-ietf-dhc-container-00

Hi, Ralph,

I agree what you said here, Scott raised the possible issue how to
differentiate the source.

One instant thinking about the two different 802.11 interface is that
the principal source policy selection will not be able to tell the
diffference, we could allow high level policy to recommend how to
handle it, give a example, we may prioritize some wifi apn policy, and
make others as just a category of normal wifi.

Anyhow, those thing need to be further studied based on the current practice.
Thanks for the discussion.

-Hui


2009/4/13 Ralph Droms <rdroms(_at_)cisco(_dot_)com>:

Hui - I think there is an issue for hosts with multiple interfaces triggered
by Scott's comments about the container option: even if a host is physically
aware that it has multiple interfaces, how does it take the characteristics
of the networks behind those interfaces into account when it merges
information?  For example, would a host process information received from a
Starbucks network over its 802.11 interface differently from information
received a home network over the 802.11 interface?

- Ralph

On Apr 12, 2009, at 2:34 AM 4/12/09, Hui Deng wrote:

Hi, Scott,

Based on the current MIF charter proposal, it consider only host.
http://www.ietf.org/mail-archive/web/mif/current/msg00367.html
I am wondering whether RG is a kind of host?

Anyhow, this discussion benefit MIF for the future consideration how
to identify the source.

Many thanks

-Hui

2009/4/11 Scott Brim <swb(_at_)employees(_dot_)org>:


Excerpts from Ralph Droms on Fri, Apr 10, 2009 03:25:49PM -0400:


Scott raises an interesting point about identifying the source of
options when delivered to clients.

BTW, Scott - what is "DHS"?


Sorry, DHCP server

The usual case - almost the only case today - is that there is a single
upstream service provider and a single source of DHCP options to be
passed along to the client.  In this scenario, there's no need to pass
along any information identifying the source of the options.

To allow for a multihomed subscriber network, I can imagine adding a tag
that would be passed along with the options so the subscriber client can
identify the source of each option.  But, what would the client do with
that information?  How would the client interpret it?  What is the
syntax
and semantics of the tagging?

Taken a step farther, sourcing information might be required even if
there is no intermediate RG and the contained option is not in use.  How
does a device with multiple interfaces make policy decisions about
information received on those multiple interfaces (which is pretty much
the question Scott asks about the container option)?

- Ralph


Well put.  It all comes down to where information is going to be
merged.  The case where a single RG client connected to multiple SP
servers is essentially already covered by MIF/6man, they just need to
document it.  If the information is merged at the RG server, then the
RG server should somehow know which interface which DHCP information
came from.  If all of the information is transparently passed to the
consumer device, then it needs the tags as well.

I don't know how the information could be usefully tagged -- the SP
server's IP address doesn't sound like a good idea.  The WG should
decide if tagging should be included in the container syntax or added
later (but documented now as needing study).

I'm CCing MIF in case people there aren't on the ietf list.

Thanks ... Scott


On Apr 7, 2009, at 2:25 PM 4/7/09, Scott Brim wrote:

I have been selected as the General Area Review Team (Gen-ART)
reviewer for this draft (for background on Gen-ART, please see
http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).

Please wait for direction from your document shepherd
or AD before posting a new version of the draft.

Document: draft-ietf-dhc-container-00
Reviewer: Scott Brim
Review Date:         7 April 2009
IESG Telechat date: 14 April 2009

Summary:

This draft is on the right track but has open issues.

Comments:

More significant:

 I am concerned about multiple interface scenarios as are being
 discussed in MIF and 6MAN, where either the RG is multiply connected
 or the end device is.  For a discussion of the sort of problems that
 lead to this concern, see (for example) notes from the MIF BOF at
 IETF74.

 - There must be a way to associate options with a particular
   upstream DHS they were obtained from, when the container is passed
   to the RG server and perhaps to the end device.  This source
   information may or may not be in the container itself -- that's up
   to the WG to decide.  If it is decided that the source information
   will not be part of the container syntax, at least the fact that
   it is necessary should be documented for people who ultimately do
   specify how container options are passed.

 - The SP server may have its ideas of how a consumer device should
   be configured, but it is not appropriate to say that the "SP
   server MUST be able to control which DHCP options are transmitted
   to the consumer device".  The RG server may need to make decisions
   about information from multiple DHCP servers.  Perhaps you could
   say that the SP server MUST be able to "provide information" to
   the RG server.

Less significant:

 5.1 and 5.2

   Alignment between the v4 and v6 descriptions would be better. The
   v4 description has "code" in the diagram and says that "code" is
   OPTION_CONTAINER_V4.  The v6 description has "OPTION_CONTAINER_V6"
   in the diagram and says that "option-code" is OPTION_CONTAINER_V6.


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