RE: [Mip4] draft-ietf-mip4-gen-ext-03.txt

["McCann Peter-A001034" <pete.mccann at motorola.com>]

We have yet to arrive at a conclusion on whether to
proceed with this draft or document a DHCP-based
solution.

It was recently pointed out to me that the DHCPINFORM
message may have some issues with reverse tunneling
due to the need to use encapsulating delivery style.
People might be concerned about the extra overhead
of this requirement.

I'd like to ask members of the DHCP community especially
to please comment to both lists; it may help to read
RFC 3024 before doing so.

I'd like to have this issue resolved before Vancouver.

-Pete


Chowdhury, Kuntal wrote:
> Hi Pete,
> 
> I think the source of the confusion is the use of DHCP options. The
> initial version of this I-D did not propose to use DHCP options at
> all.  
> The proposal contained a few possible host config parameters that we
> would have defined. However, someone saw the light, and suggested
> that instead of redesigning the host config options from scratch, why
> not we used the options and the format of the options carrying config
> info as defined in DHCP. It made sense; hence we decided to accept
> that approach.     
> 
> Now, I see that people are mixing the use of DHCP protocol with MIP4
> host config options. I think this is a digression that we should
> avoid.  
> We need to understand the scope of the I-D. It does not rule out
> other ways to do host configuration when the MN is using MIP4. It
> defines _a_ way that is Mobile IP specific. It is also the most
> efficient one from the number of round trips point of view.   
> 
> When you say that running DHCP inside MIP4 tunnel allows for a single
> protocol to be used whether the MN is at home or visiting, I have a
> question. How is it possible for the MN to fetch config info from the
> visited network when RT is negotiated and enforced at the FA?   
> 
> BTW, the approach specified in the draft-ietf-mip4-gen-ext-03.txt
> allows the use of a single protocol i.e. MIP4 to be used to fetch
> config info from home and visited networks, not to mention with fewer
> number of messages.   
> 
> Another issue that we need to think about the use of DHCP inside MIP4
> tunnel is security. We cannot prohibit the MN to run DHCPINFORM only,
> right? The MN may start doing IP address config (lease and release).
> How to secure these DHCP messages? If we intend to only allow the MN
> to send DHCPINFORM, how do we prevent it from sending other DHCP
> messages?     
> 
> AFAIK, RFC 3118 is not widely implemented and used. Even if it is, we
> can't expect the MIP4 implementations to start implementing RFC 3118
> just to get a few config info from the home domain.  
> 
> Regards,
> Kuntal
> 
>> -----Original Message-----
>> From: McCann Peter-A001034 [mailto:pete.mccann at motorola.com]
>> Sent: Tuesday, July 31, 2007 9:01 AM
>> To: mip4 at ietf.org; dhcwg at ietf.org
>> Subject: [Mip4] draft-ietf-mip4-gen-ext-03.txt
>> 
>> A question has arisen during the last call for
>> draft-ietf-mip4-gen-ext-03.txt.
>> 
>> The draft includes the following text:
>> 
>>     There are mechanisms
>>     such as DHCP for the mobile node to configure information from
>>     the foreign network, but not from the home network when the
>>     mobile node is not attached to the home network.
>> 
>> However, this may not be strictly true.  In particular, it might be
>> possible to use a DHCPINFORM message through the tunnel that was
>> established with Mobile IP, thus eliminating the need to encode DHCP
>> options inside Mobile IP messages.
>> This would allow for a single configuration protocol to be used
>> whether the MN is at home or visiting.
>> 
>> I think we may have touched on this question during our last
>> chartering discussion but we might not have explored all the
>> ramifications.  Please, if you have an opinion either way express it
>> now and give some background as to why you think so.
>> It is possible that we might turn this draft into a BCP-like document
>> for how to configure and run DHCP over the tunnel to the home
>> network. 
>> 
>> -Pete


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