Subject: [NSIS] RE: Suggestions on Multi-homing section of Mobility Draft

From: "Shivanajay Marwaha" <[email-masked]>
Date: Tue, 21 Feb 2006 17:30:33 +0800

Dear Sung-Hyuck,

Thanks for your feedback on our suggestions. 
Here are some comments embedded in-line.

Regards,
Shivanajay 

-----Original Message-----
From: Sung-Hyuck Lee [mailto:[email-masked]] 

Dear Shivanajay,

Thank you for your interests.
Please refer to my comments in line.

Warm regards,
Sung-Hyuck

----- Original Message -----
From: "Shivanajay Marwaha" <[email-masked]>

> Dear Sung-Hyuck, Seong-Ho, Mobility Applicabilty Draft Authors and 
> other NSIS WG members,
>  
> We have been studying the NSIS Mobility Applicability draft 
> http://www.ietf.org/internet-drafts/draft-ietf-nsis-applicability-mo
> bili ty-signaling-03.txt and have some suggestions. 
>  
> Here are few of the Comments/suggestion on section 5 in the NSIS 
> mobility applicability draft:- (More to follow in the subsequent 
> emails :)
> 
> ------------------------------------------------------------
> Suggestion 1 -
> General introduction of multihoming seems to be lacking
> 
> Discussion -
> In section 5.2, current text lacks a general introduction to 
> multihoming. The first two sentences talk only about a specific
> issue  concerning multihomed host. Therefore it would be better to
> include  some general description of multihoming environment to
> give readers a  complete picture. In our view, the text from
> section
> 5.2.1 of version 02 suits the
> Purpose better. So, we suggest that the first two sentences of
> section  5.2 be replaced with the following text (from section
> 5.2.1 of version 02):-
>  
> Suggested Text -
> "Multihoming refers to a situation where an end node has several 
> parallel communication paths to use.  An end node (e.g., an MN in 
> mobile environments) may have multiple homogeneous/heterogeneous 
> interfaces.  Multiple interfaces can be used in order to increase 
> bandwidth availability or to select the most appropriate interface 
> according to the type of flow or choices of the user [17].
>  
> Basically, each network interface has different performance, 
> bandwidth, access range, and reliability.  Users may want to select
>   the most appropriate set of network interface(s) depending on the
>  network environment, particularly in wireless networks which are
> less  reliable than wired networks.  Users may also want to select
> the most  appropriate interface based on certain criteria or to
> combine a set of  interfaces to get sufficient bandwidth [17].
> 
> In multihomed environments, multiple addresses can be allocated to 
> either a single interface or multiple interfaces to provide
> ubiquitous  and fault-tolerant access to the Internet.  Other
> benefits of having  multiple interfaces include load balancing,
> bi-casting, load sharing,  and etc."

[SHL] It is not easy to evaluate which introduction is better because
we need to consider various views on editing of drafts: The way of
editing can be different dependent on what preference is, simpler or
more detailed expression. Till now, the mobility authors have tried
to make the mobility draft simpler with clearer text. However, the
authors will refer to your valuable comments.

**********************************************************************
[SHIV] Thanks. We understand your difficulty in carefully choosing
the text so as to keep it simple :) In our opinion a general
description of multihoming environment would be good for the sake of
completeness and better clarity. If required we can contribute some
brief text (2-3 sentences) for the same.  
**********************************************************************

> ------------------------------------------------------------------
> 
> Suggestion 2 -
> Section 5.2.1, Para below Figure 14: (homogenous interface vs.
> multiple interfaces)
>
> Current text: - (Section 5.2.1)
> " We assumed homogeneous wireless interfaces in this draft although
>  multihoming with multiple interfaces would be more efficient on 
> heterogeneous interfaces due to the increased path diversity.  The 
> issues on heterogeneous interfaces are for further study. "
> 
> Discussion -
> According to the diagram the issue discussed in this section is
> about  using one connection for communication (although multiple
> connections  may be available/possible). This does not even depends
> on the number  of interfaces available on the MN, since in a site
> multihoming 
> environment, MN can still have multiple address (in turn multiple 
> connections to CN) on one interface.  Therefore, the use of 
> "homogeneous" and "heterogeneous" in the above text does not
> reflect  the actual issue. It would be better to clarify the
> difference.
> Furthermore, in section 5.2.5, some discussion was provided about
> the  case of using mulitple connections. This should be also
> reflected in  the text. So we suggest to replace the 4th paragraph
> of section 5.2.1  with following text:

[SHL] You seem to misunderstand the terms, "homogeneous" and
"heterogeneous".  Homogeneous interfaces mean that the interfaces
consist just same physical air interface, for example, only IEEE
802.11. 
Heterogeneous interfaces mean that the interfaces simultaneously
consist different physical air interfaces, for example, WIFI and 3G,
WIFI and WIMAX/WiBro, etc.

**********************************************************************
[SHIV] Actually what we meant was that, in our opinion the said
problem is not limited to "homogenous" case only. Perhaps the
reference of the problem to "homogenous" case can be amended/deleted
so as to avoid any confusion in the minds of the readers (since the
problem of selection of appropriate interface/s will also arise in
"heterogenous" case.)
**********************************************************************

> Suggested Text -
> "This section deals with the scenario where only one connection is 
> used for data traffic at a time. In some case multiple connections
> via  heterogeneous interfaces may be necessary and more efficient.
> Discussion about host multihoming issues is included in section
> 5.2.5 of this draft"
> 
> Regards,
> Shivanajay Marwaha
> (On Behalf of Takako Sanda, Toyoki Ue and Cheng Hong)

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---

From: Sung-Hyuck Lee <[email-masked]>
Date: Wed, 22 Feb 2006 14:47:42 +0900

Hi Shivanajay,

----------------------- chopped --------------------------------------------------------------------
? 
> WIFI and WIMAX/WiBro, etc.
? 
[SHL] Actually, in Section 5.2, the authors of the mobility draft have tried 
to mainly address host multihoming-related issues rather than site 
multihoming-related those according to feedbacks from NSIS folks. That is,
the host multihoming with multiple interfaces/addresses was assumed in 
this section. The scenarios on heterogeneous interfaces may be different 
from those on homogeneous cases. Therefore, the authors thought that 
the heterogeneous-related issues needed to be for further study, and IMO, 
those issues may need to be discussed at separate documents. However, 
the authors can consider your comments on "homogenous" and 
"heterogeneous" terms

Kind regards, 
 
Sung-Hyuck