Subject: Re: [netlmm] Consensus call: Adopting draft-korhonen-netlmm-lma-discovery as a WG item

From: Christian Vogt <[email-masked]>
Date: Mon, 18 May 2009 20:17:41 -0700

Hi Vijay -

> The current text does not talk about embedding the "host identifier"  
> in the
> LMA FQDN. It says
>
>  Once the MAG has acquired the MN identity, the MAG can use the
>  information embedded in the identity to construct a generic LMA FQDN
>  (based on some pre-configured formatting rules) and then proceed to
>  resolve the LMA IP address(es) using the DNS.
>
> I agree it could be interpreted as including the host identifier in  
> the LMA
> FQDN. But, AFAIK, that was not the intention. Jouni?

Yes, I interpreted it as including the host identifier in the LMA FQDN.
Now I see what you intended it to mean.  Perhaps you could reword to:

  Once the MAG has acquired the MN identity, the MAG can use the
  information embedded in the MN identity to identify the MN's home
  domain, construct an LMA FQDN based on this home domain and a
  well-known prefix denoting "LMA", and proceed to resolve LMA IP
  address(es) using this LMA FQDN.

This said, the method that Julien and I were describing, i.e., encoding
the MN identity in the FQDN, is also possible.  It is not that this
would be a preferred method.  In fact, it has significant disadvantages.
But since it is possible, I think you should make the modifications to
section 5 that I had originally suggested, because the text in section 5
does not consider this possibility.  Anyway, it's just a nit.

- Christian

---

From: jouni korhonen <[email-masked]>
Date: Tue, 19 May 2009 08:24:04 +0300

On May 19, 2009, at 2:30 AM, Vijay Devarapalli wrote:

> Hi Christian,
>
> On 5/18/09 4:13 PM, "Christian Vogt" wrote:
>>

[snip]

>> It consists of encoding a
>> mobile host identifier in the DNS query name, as Julien pointed out
>> correctly in his email.
>

The original intention was, as Vijay pointed out, generating a generic  
LMA FQDN out of MN identity that would not necessarily identify a  
specific LMA. Later in the paragraph that Vijay quoted it says:

...
identity must embed information elements that can be extracted and at
minimum used to determine the entity hosting and operating the LMA
for the MN.  Thus the MN identity in this solution cannot be a "flat"
identity without any structure and "clear text" parts containing the
hosting entity information.  Examples of such identities are the ...

The text talks of "LMA hosting entity" granularity. I admit that the  
same text could easily fit into cases where a MN identity were used to  
name individual LMAs.

/Jouni

---

From: jouni korhonen <[email-masked]>
Date: Tue, 19 May 2009 08:24:19 +0300

[snip]

...

/Jouni

---

From: Julien Laganier <[email-masked]>
Date: Tue, 19 May 2009 18:04:49 +0200

On Tuesday 19 May 2009, Vijay Devarapalli wrote:
> 
> [...]
>
> > Now that we are discussing this:  Perhaps you could also use some
> > text from Julien's email to elaborate a bit on the said method for
> > DNS-based mobile-host-specific LMA assignments?  Julien, would that
> > be OK?
>
> Hmm... Julien's proposal does not take into account pools of LMAs.
> For example, (quoting from Julien's email), lma-sfbay.example.com
> could actually be a two LMAs, identified by two IP addresses sharing
> the load for sfbay. When you do a lookup for lma-sfbay.example.com,
> you could get one of the two LMAs. It might not the same all the time
> for a particular mobile node.

With the strawman mechanism I proposed earlier you would make sure that 
each LMA get assigned a different FQDN. That would provide for load 
balancing since the LMA is picked based on a modulo of the IMSI.

As to the general idea of assigning a single FQDN to a stateful service 
implemented by more than one node while there are no state 
synchronization mechanism between these nodes, I think it is 
problematic in itself. 

--julien

---

From: Julien Laganier <[email-masked]>
Date: Tue, 19 May 2009 18:12:27 +0200

On Tuesday 19 May 2009, Christian Vogt wrote:
> Hi Vijay -
>
> > The current text does not talk about embedding the "host
> > identifier" in the
> > LMA FQDN. It says
> >
> >  information embedded in the identity to construct a generic LMA
> > FQDN (based on some pre-configured formatting rules) and then
> > proceed to resolve the LMA IP address(es) using the DNS.
> >
> Yes, I interpreted it as including the host identifier in the LMA
> FQDN. Now I see what you intended it to mean.  Perhaps you could
> reword to:
>
> This said, the method that Julien and I were describing, i.e.,
> encoding the MN identity in the FQDN, is also possible. [...]

Sorry to repeat myself but just to make sure I get things right. What I 
was proposing is to use the MNID as an input to an algorithm that 
deterministically assign the same LMA out of a pool of LMAs.

--julien

---

From: Behcet Sarikaya <[email-masked]>
Date: Tue, 19 May 2009 12:34:25 -0700 (PDT)

Hi Julien,
  I think you are suggesting in this and previous emails a different kind of DNS access which is not covered in Jouni-Vijay draft.
  I do have draft about it and will publish it soon.

Regards,

Behcet

----- Original Message ----
From: Julien Laganier <[email-masked]>
To: Christian Vogt <[email-masked]>
Cc: NETLMM Mailing List <[email-masked]>
Sent: Tuesday, May 19, 2009 11:12:27 AM
Subject: Re: [netlmm] Consensus call: Adopting draft-korhonen-netlmm-lma-discovery as a WG item

--julien
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