[Ospf-manet] Re: Regarding OSPF MDR

Richard Ogier <rich.ogier@earthlink.net> Sat, 10 February 2007 18:24 UTC

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Date: Sat, 10 Feb 2007 10:24:07 -0800
From: Richard Ogier <rich.ogier@earthlink.net>
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Subject: [Ospf-manet] Re: Regarding OSPF MDR
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I didn't reply to the following comment, because I thought I already
addressed it in my previous email.  But I will add a few comments.

> 4. The GTNet MDR implementation artificially distorts link metrics as 
> a way of expressing both the actual cost and the property 
> (synchronized or not) of the link as one. This approach is, not 
> specified in the MDR draft, so also on this point the GTNet MDR 
> implementation and the MDR draft exhibit a significant discrepency.

I guess the word "artificial" is the opposite of "natural", and the
use of such vague words has already been discussed.

It is acceptable to allow the link metric to depend on link
quality, as you know (since OLSR does this).  Link quality
can be measured in many ways.  For example, if n consecutive
Hellos have been received from the neighbor, the link metric
can be decreased to represent good link quality.
Similarly, if database exchange has been completed with the
neighbor, so that its state becomes Full, this implies the link
is likely to have better quality, so we can decrease the link
metric slightly to prefer it over non-Full neighbors.

Since you are bothered that this is not specified in the MDR
draft, I can add something like the following to the next
draft update: "The router MAY add a small penalty to the metric
of links to neighbors that are not Full".

Also, we can run simulations both with and without this technique,
after the updated version of OSPF-MDR has been implemented
in GTNetS.


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