Saturday, February 6, 2010

HSMM report 6 Feb 2010

Greetings MEPsters,

Today I was able to configure two WRT54GLs running OpenWRT. One was an access point with a wired connection to the internet, and the other was configured as a bridge. Beagleboards were attached to both of the WRT54GLs, and I could ping from both of them.

Here is a whiteboard block diagram of how these routers are configured.

If that's too small (sorry about the white balance) then try this larger image.

Today, I watched a webinar about High-Speed Multimedia Webinar. I noticed the webinar at the last minute - otherwise I would have mentioned it earlier.

Here's the writeup about it.


HSMM-MESH(tm) Networking Seminar

The HSMM-MESH(tm) Networking Seminar will cover all aspects of the HSMM-MESH
software developed in Austin, TX. The Webinar will begin with an explanation of
High-Speed Multi-Media (HSMM) and the subset of this topic which uses modified
Linksys WRT54GL 2.4 GHz Wireless Routers to form a mesh network, handy for high
speed digital communications in the ham band - for emergencies, special events
and field day.

The Webinar will cover applications, antennas, hardware, and the software. You
will learn how to load the software and how to configure it.

In the second part there will be a lab where we will actually load the software
into a router and configure the router. You will need a Linksys WRT54GL (any
version) or a WRT54G (Version 1.1 through 4 - version 5 or higher
will NOT work.)

The Webinar will be online at 8:00am Central time to give you a chance to get
logged in and test your setup before something starts happening. Training
starts at 9:00am with 10 minute breaks about every hour. And we will finish
in the afternoon after a lunch break.

You should Register before Saturday morning if possible. . If you have a
microphone and headset you will be able to ask questions verbally over VOIP.
Otherwise you can type in questions to be able to interact with the speaker.

The Webinar is provided through the courtesy of Ham-Com and is presented by
members of the NTMS-HSMM and Austin-HSMM groups. (


There was a third part. Some of the third part was recorded by Jordan Cronin, and those recordings (he warned the quality might not be as good as he would like) can be found here:

The seminar introduced HSMM and gave specific examples of its use in public service events. The configuration of their specific build of OpenWRT followed.

Read more about HSMM-MESH here:

For our application, I think there is a wrinkle with the HSMM-MESH software. On the hsmm-mesh site, I read the following passage.

"One feature of OLSR is called the "dynamic default gateway". When a node has internet access, as verified by periodic pings of various internet servers, it tells its neighbors that internet is available and the surrounding nodes will use this node as its default gateway. This is how every node gains internet access even if only one of them is connected to the internet. It still works if multiple nodes have direct internet access, but its behavior in this mode is not well tested. Sporadic internet access such as web browsing should handle this well. However, connections intended to be continuous, like streaming media, will definitely come to a halt if internet access switches from one node to another. This is because the IP address that you are accessing the internet from just changed and the far end will close the connection, as it should."

This sounds like that video streams would be interrupted? In our case, maybe we should investigate mobile IP? There is an RFC for mobile IP over IPv6, located here:

I have this printed out and have plans to read it. There is another RFC for IPv4 as well. It's located here:

The OLSR RFC can be found here:

If you're lost in RFCs, then take heart - I am too!

What I'd like to do is get some sort of feeling as to what we'd have to add (if anything) to a build like OpenWRT in order to turn wireless routers into MEP prototypes.

The next step for the WRT54GLs here is to send video, with the source coming from USB webcams.

-Michelle W5NYV

No comments: