Subject: Re: uni-directional links discussions in DSR draft

From: Kevin Grace <[email-masked]>
Date: Tue, 02 Jan 2001 07:06:50 -0500

> I am interested to know which routing protocols do not work correctly over
> uni-directional links.

The MobileMesh routing protocol works well over uni-directional links.
You can read more about it here:

   http://www.ietf.org/internet-drafts/draft-grace-manet-mmrp-00.txt

Also, the MobileMesh protocol has been implemented in an Open Source
Linux software distribution which may be downloaded here:

   http://www.mitre.org/tech_transfer/mobilemesh/

Thanks,
Kevin

------------------------------------------ 
Kevin Grace          The MITRE Corporation 
781-271-8388         202 Burlington Rd
[email-masked]     Bedford MA, 01730Li Li wrote:

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From: Kenneth Brayer <[email-masked]>
Date: Tue, 02 Jan 2001 11:03:36 -0800

The Survivable C3 Routing Algorithm was designed for unidirectional
links. It can be found in Packet Switching for Mobile Earth Stations via
Low-Orbit Satellite Network, K. Brayer, Proceedings of the IEEE,
November 1984. This paper is referenced in the patent for the Iridium
satellite network. I do not know whether or not the Iridium people used
the algorithm or other elements of the paper in their network.
Kenneth Brayer

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From: [email-masked]
Date: Thu, 04 Jan 2001 15:55:50 +0100

Happy millenium for everybody!

It is not clear whether the question is:

Which protocols function correctly with bi_D links but may not function
correctly in presence of uni_D links?

for example, AODV, DSR, if some amendments are not introduced.

or:

Which protocols function correctly in presence of uni_D links but route
only on bi_D links?

for example FSR, OLSR, TBRPF... 

Added to this issue there is also the issue about the link layer which is
in general bi-D link oriented like in IEEE802.11, Hiperlan, Bluetooth. In
this case routing on bi-D links is mandatory. I don't know uni_D link
oriented MAC but in this case the link control is either unreliable or very
complicated. 
I think DSR has something very complicated in case of uni_D, and some
feature of route caching would probably need to be disabled. In presence of
some uni_D links together with a bi_D MAC there are also serious sources of
flaws. 

Philippe

A 00:08 22/12/00 -0500, Li Li a écrit :
>In the DSR draft, it says "Although many routing protocols operate correctly
>only over bi-directional links, DSR can successfully discover and forward
>packets over paths that contain uni-directional links."
>
>For DSR to take advantage of uni-directional links (assume a compatible
>MAC), DSR requires the route request destination do a seperate route
>discovery. Route caching has to be careful to distinguish uni-directional
>and bidirectional links. Are these the complete picture for DSR to factor in
>uni-directional links?
>
>Thanks,
>
>Li
>