Re: [Autoconf] updated draft on aspects of multi-hop wireless communication

"Teco Boot" <teco@inf-net.nl> Wed, 25 February 2009 09:16 UTC

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From: "Teco Boot" <teco@inf-net.nl>
To: "'Emmanuel Baccelli'" <Emmanuel.Baccelli@inria.fr>
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Date: Wed, 25 Feb 2009 10:16:26 +0100
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Subject: Re: [Autoconf] updated draft on aspects of multi-hop wireless communication
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Thanks for the updated draft.
Here some feedback:

On exposed node: I do not understand what is mentioned here. I think the
exposed node problem is communication from A to B (correct) and C to D
(reverse direction of arrow). With CSMA, transmit from C is delayed because
C noticed carrier busy caused by transmit from A (or CSMA/CA virtual carrier
sense by CTS from B) . The delay was not needed, as C transmission does not
affect B reception of frame transmitted by A.
I think exposed node is more a research problem and less an operational
problem.

On Hidden Terminal: I think this __is__ an operational problem, but handled
in some or many cases by a media access mechanism, like CSMA/CA or TDMA.
Some / many cases implies "not all" cases, e.g. CSMA/CA does not work for
multicast. And multicast may be of large importance in MANETs, e.g. MANET
routing protocol flooding.

I suggest swapping the two problems, mentioning the important one first.


The draft emphasizes problems introduced by limited radio range. Note that
it has also a welcome characteristic, that is spatial reuse. Be positive on
wireless communication one time ? :-)


Once again, I think:
  - We may say that router B is a neighbor of router A. In this
  terminology, there is no guarantee that router A is a neighbor of
  router B, even if router B a neighbor of router A.
is incorrect. B hears A and I would say A is a neighbor of A and A is listed
in B's neighbor table.
Is there a reason not to update the text, as we agreed on before?


Teco.



|-----Oorspronkelijk bericht-----
|Van: autoconf-bounces@ietf.org [mailto:autoconf-bounces@ietf.org] Namens
|Emmanuel Baccelli
|Verzonden: maandag 23 februari 2009 11:04
|Aan: autoconf@ietf.org
|Onderwerp: [Autoconf] updated draft on aspects of multi-hop wireless
|communication
|
|Hi all,
|
|
|following the fruitful discussions about initial version of the
|document,
|here is an update to the draft describing aspects of multi-hop wireless
|communication:
|
|http://www.ietf.org/internet-drafts/draft-baccelli-multi-hop-wireless-
|commun
|ication-01.txt
|
|
|Again, the goal of this document is to identify a consensus about this
|topic, and then use this to move on quicker with the rest of the work...
|
|Please review it, and provide feedback as soon as possible.
|
|
|Cheers
|
|Emmanuel