Subject: [manet] New Version Notification for draft-ivancic-manet-modemlpa-00.txt

From: "Ivancic, William D. (GRC-RHN0)" <[email-masked]>
Date: Mon, 5 Nov 2012 15:31:53 -0600

I uploaded the modemlpa draft.  Unfortunately, I cannot be at the meeting this week.

- Will

A new version of I-D, draft-ivancic-manet-modemlpa-00.txt
has been successfully submitted by William Ivancic and posted to the
IETF repository.

Filename: draft-ivancic-manet-modemlpa
Revision: 00
Title: Modem Link Properties Advertisement Protocol
Creation date: 2012-11-05
WG ID: Individual Submission
Number of pages: 20
URL:             http://www.ietf.org/internet-drafts/draft-ivancic-manet-modemlpa-00.txt
Status:          http://datatracker.ietf.org/doc/draft-ivancic-manet-modemlpa
Htmlized:        http://tools.ietf.org/html/draft-ivancic-manet-modemlpa-00

Abstract:
  Nework devices and applications are increasingly connected to a
  variety of smart modems whose incoming and outgoing link rates can be
  varied over time to suit the channel characteristics.  Such rate
  changes can result from use of adaptive coding and modulation.  The
  link rate and conditions offered by the modem to connected devices
  therefore vary.  In order for connected devices and applications to
  get the most out of the modem's link capacity, it is necessary for
  the applications and connected devices to condition traffic.  Thus,
  they need some knowledge of the modem's link conditions.  This
  document describes one simple method for a modem to advertise link
  rate and other characteristics, via UDP messages, and discusses
  alternative approaches to communicating this information.  While the
  mechanism in this document is described in the context of a modem, it
  can also be broadly applied to other scenarios such as cryptographic
  devices.

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From: "Ward, David - 0663 - MITLL" <[email-masked]>
Date: Mon, 5 Nov 2012 22:19:23 -0500

>     I uploaded the modemlpa draft.  Unfortunately, I cannot be at the

Hi Will,

I'm not sure that I agree with extending layer 2 information beyond the 
radio-to-router interface.  Looking at figure 4, how will the 
host/application know which way the router is going to forward packets, 
in order to control its output data rate?  I think the mechanism to 
control the rate of your application traffic should be separate from the 
radio-to-router interface.

David

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From: Abdussalam Baryun <[email-masked]>
Date: Tue, 6 Nov 2012 12:46:37 +0100

+1

AB

On 11/6/12, Ward, David - 0663 - MITLL <[email-masked]> wrote:
> _______________________________________________
> manet mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/manet
>

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From: "Ivancic, William D. (GRC-RHN0)" <[email-masked]>
Date: Fri, 9 Nov 2012 08:16:36 -0600

David,

Often for end-systems such as those found in many manets, there is only one WAN with a router attached that is either routing traffic off the system or between local nodes.  Conversely, there may not even be a router attached, just a host system attached to a radio.  ModemLPA offers a very simple way to communicate layer 2 information to systems  and applications upstream from the radio.  Sometimes rate is important.  Other times link up/down is useful.  Certainly for something like store/carry/forward distributed applications know that the link is down is useful.

- Will

---

From: "Ward, David - 0663 - MITLL" <[email-masked]>
Date: Fri, 9 Nov 2012 10:16:47 -0500

Will,

So then, how does the application know whether it is serving up traffic 
to another attached LAN (where it does not need to constrain its output 
to the radio's rate limit) or the radio WAN (where it does)?

There are plenty of MANETs where you assumption does not hold (like ones 
I deal with), and I'm afraid that standardizing an approach where you 
make that kind of assumption could cause major headaches elsewhere when 
that gets implemented.  I know the intent is to optimize the application 
for the network, but this seems like a pretty gross violation of layer 
separation principles.

How about we take the time to come up with an approach that will solve 
the general case of rate-limiting application traffic using feedback 
from the routing layer (where only the router will be getting the radio 
metrics and using them appropriately)?  This problem isn't necessarily 
specific to MANETs or even wireless links.

David

On 11/09/2012 09:16 AM, Ivancic, William D. (GRC-RHN0) wrote:
> Re: New Version Notification for draft-ivancic-manet-modemlpa-00.txt
>
> David,
>
> Often for end-systems such as those found in many manets, there is 
> only one WAN with a router attached that is either routing traffic off 
> the system or between local nodes. Conversely, there may not even be a 
> router attached, just a host system attached to a radio.  ModemLPA 
> offers a very simple way to communicate layer 2 information to 
> systems  and applications upstream from the radio.  Sometimes rate is 
> important.  Other times link up/down is useful.  Certainly for 
> something like store/carry/forward distributed applications know that 
> the link is down is useful.
>
> - Will
>
> >
> > Hi Will,
> >

-- 
David Ward, Associate Staff
Wideband Tactical Networking Group
MIT Lincoln Laboratory
Office: 781-981-4266
Mobile: 781-999-1925
Fax: 781-981-4583