Subject: [Mip6] I-D ACTION:draft-ietf-mip6-hiopt-03.txt

From: [email-masked]
Date: Wed, 16 May 2007 15:50:02 -0400

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.
This draft is a work item of the Mobility for IPv6 Working Group of the IETF.

	Title		: DHCP Option for Home Information Discovery in MIPv6
	Author(s)	: H. Jang, et al.
	Filename	: draft-ietf-mip6-hiopt-03.txt
	Pages		: 19
	Date		: 2007-5-16
	
This draft defines a DHCP-based scheme to enable dynamic discovery of
   Mobile IPv6 home agent address, home agent FQDN and home subnet.  New
   DHCP options are defined to carry the information from a DHCP server
   to the DHCP client running on the mobile node.

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From: "Kilian Weniger" <[email-masked]>
Date: Wed, 23 May 2007 16:35:15 +0200

Hi Heejin,

I quickly went through the new version of the hiopt draft. As announced
at the last meeting and on the mailing list, the assignment of HAs from
an MSP that is neither ASP nor MSA but has trust relationship with MN's
MSA is now supported. This is good, since it improves deployment
flexibility and applicability. However, I have some questions regarding
the related text in the draft.

The Home Network Identifier option currently has three id-types: 0 for
"Visited domain/ASP", type 1 for "target network" and type 2 for "No
preference". The id-type in combination with the Home Network Identifier
field allow the MN to request a specific MSP.

Section 3.1 says about the Home Network Identifier field: "...This field
MUST be set to the network realm as the FQDN defined in [3] when the
id-type is 1.". Later, the text says "The id-type 1 indicates the mobile
node is interested in learning the home network information that
pertains to the given realm. ... The target network can be a home MSP or
a MSP which has trust roaming relationship with the mobile node's home
MSP." Isn't this contradicting? How can the MN request the assignment of
an MSP different from the MSA, when the Home Network Identifier field
must be set to the realm of the MN's NAI (The realm of the MN's NAI
typically pertains to the MSA)? Or does the "network realm" in the cited
sentence refer to something else than the MN's NAI?

Another comment relates to the text about id-type 2. It is not clear to
me whether id-type 2 can be used by the MN to request the assignment of
an MSP that is neither ASP nor MSA. Section 4.3, case C says:

  "In this case, the assignment of the home information relies on the
   server's local policy, and the DHCP server SHOULD have its own policy
   so that it can reply with the proper information.  "
...
   "When the DHCP server provides the home information that is retrieved
   from the MIP6 Relay Agent option, it MUST compare the NAI's realm
   information of MN-NAI option with the target network in Home Network
   Identifier option.  If they match, the DHCP server replies with the
   Reply message after copying the home information in MIP6 Relay Agent
   option to Home Network Information option.

   In case the server cannot find any home information for the requested
   id-type, it MUST return a Home Network Information option with the
   0-length data."

What should the DHCP server do if the MIP6 relay agent option contains
multiple sub-options and one of the sub-options matches the NAI's realm
whereas another one does not? This situation can happen if the AAAH
sends home network information for mutliple MSPs to the NAS (e.g., for
home MSP/MSA and other MSPs with trust relationship to MSA). Should the
server respond with multiple Home Network Information Sub-options?

And why do we need this MN-NAI option check here at all?

Thanks,

Kilian

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> Sent: Mittwoch, 16. Mai 2007 21:50
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> Subject: I-D ACTION:draft-ietf-mip6-hiopt-03.txt 
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---

From: "Premec, Domagoj" <[email-masked]>
Date: Thu, 31 May 2007 17:56:33 +0200

Hi Heejin,

I have a clarification question: if the MN requests information about several target networks it will include several Home Network Identifier options. The following text 

>   Multiple sub-options may exist in a Home Network Information option
>   to carry more than one home information.

leaves impression that the response message contains only one Home Network Information option which carries the addresses, prefixes and/or FQDNs of all target networks. I could be wrong, but I couldn't find any text that is specific about this. 

If the information about multiple target networks is carried in a single Home Network Information option, the MN may not be able to match the info from the Home Network Information option to a particular target network. For example, the MN may ask for infomation about operator1.com and operator2.com, and the Home Network Information option may contain the home subnet prefix and the FQDN. How would the MN know if both suboptions carry information about operator1.com or if subnet belongs to operator1 and FQDN to operator 2?

thanks
domagoj

> Sent: 16. svibanj 2007 21:50
> Subject: [Mip6] I-D ACTION:draft-ietf-mip6-hiopt-03.txt 
> 
> A New Internet-Draft is available from the on-line 
> Internet-Drafts directories.
> To remove yourself from the I-D Announcement list, send a 
> message to [email-masked] with the word 
> unsubscribe in the body of the message. 
> Internet-Drafts are also available by anonymous FTP. Login 
> with the username "anonymous" and a password of your e-mail 
> address. After logging in, type "cd internet-drafts" and then 
> http://www.ietf.org/shadow.html or 
> ftp://ftp.ietf.org/ietf/1shadow-sites.txt
> 
> Below is the data which will enable a MIME compliant mail 
> reader implementation to automatically retrieve the ASCII 
> version of the Internet-Draft.
>