[Olsr-dev] OLSRd with ETT available

Hannes Gredler (spam-protected)
Sun Feb 10 16:34:36 CET 2008


this is fantastic news ! -

you might want to sync your efforts with henning rogge. -
henning has graciously offered to refactor the link_set code and
modularize it such that any link metric calculation of your taste
can be hooked into as an plugin.


Erik Tromp wrote:
> Hello All,
> This is to announce the availability of the first release of OLSR-LC.
> OLSR-LC is OLSR enhanced with link-cost extensions. OLSR-LC was initially
> developed on version 0.4.10 of OLSRd, and was ported up to version 0.5.3 .
> In the coming weeks I will put effort in porting the extensions up to the
> most recent versions of OLSRD, versions 0.5.4 and 0.5.5 .
> The link-cost extensions were developed at Thales Communication, Huizen,
> Netherlands, and is currently maintained by Erik Tromp, Avantec Engineering
> ( www.avantec.nl )
> You can get a copy of the source code at:
>   http://sourceforge.net/projects/olsr-lc
> How to install it: download the file olsrd-0.5.3-lc-0.1.tar.gz from the
> above URL into a directory of your choice.
> At the command prompt, cd to the directory in which you saved the downloaded
> file, and type:
>   tar -zxvf ./olsrd-0.5.3-lc-0.1.tar.gz
> This will create the directory olsrd-0.5.3-lc-0.1 and unpack all source
> files in that directory.
> Then type:
>   cd olsrd-0.5.3-lc-0.1
>   make build_all
> followed by:
>   make install_all
> In the lib directory you will find a sub-directory ett . This contains a
> basic setup of a plugin that can be used to calculate link costs based on
> Expected Transmission Time (ETT) . For ETT you need the medium speed
> (Mbit/s). Then you can use the formula:
>  ETT = ETX * #bits / bitspeed
> The actual implementation of this plugin is still to be written. Currently
> the plugin does nothing more than to set the link speed of each available
> neighbor link every 10 seconds to a random value of either 1 or 2 Mbit/sec .
> An actual implementation of the ETT plugin could be based on measuring, once
> every so many minutes, the speed of the available links with all the
> neighbors.
> This could be done using the well-known packet-pair technique. That approach
> would be purely layer-3, so no interfacing with layer-2 metrics.
> An alternative to measuring (via RTT or packet-pair methods) would be to
> write a plugin that retrieves layer 2 information. An existing
> implementation might be found the XIAN framework; see
> http://xian.sourceforge.net/ .
> Of course there are many other ways to measure the speed. And, in absence of
> any automatic measuring method, one could also fall back to setting the
> speed values manually to a fixed (pre-configured) value. The initial speed
> values, together with other link cost values, can be configured in the
> olsrd.conf file; for an example see ...\files\olsrd.conf.default.lq .
> If you have an example of source code that can read out layer-2 metrics I
> would be very interested !
> As always: have fun with it!
> Erik Tromp

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