Notices

I was looking around the downloads today and notice this app:

DT-Talkie v2.1

http://maemo.org/downloads/product/OS2008/dttalkie/

If I read the description right, it sounds like you can communicate to other N8x0 with having a network connection. Does anyone have two N8x0 to try this out? And if it does work, what's the range on this?

Thanks.

Wow, thanks for finding that! I have two N800s, I'll try it out soon!

I'm still a bit unclear myself... What kind of networking does it use? Ad-hoc WiFi?

From the website:

.... Aha, later on, they say they're using Bluetooth....

So your walkie-talkies only work in BT range? Couldn't you just, you know, talk loudly?

I've built the DTN2 reference implementation from the tip at sourceforge this week, for diablo, if anyone wants me to post some debs. They carry the Bundle Protocol used in DTNs directly over bluetooth and/or TCP/IP. Let me know if anyone wants them.

More info at dtnrg.org and the source is at dtn.sourceforge.net

I've not yet tried DTN-talkie properly, as I've not had anyone else to try it with, but I have got a 7 node DTN up and running, including an N800, an NSLU2 (running Debian), 2 Macs (PowerPC and Intel) and a bunch of other Linux nodes, and a dedicated server in a data-centre, at delaytolerant.net.

I've uploaded a pair of debs for liboasys and DTN2 that seem to work fine on Diablo. These also are built against avahi, so bonjour discovery works for automatically connecting to peers with TCP/IP, and nodes offering bluetooth interfaces are automatically connected to when discovered. You will need to configure a bit of stuff in /etc/dtn.conf - I can provide some help if you need it.

As a networking technology, it is pretty cool, and there's plenty of interest in Finland, so maybe it will spread to Nokia.

This is the same protocol that NASA are starting to use for deep-space networks, and recently deployed on the ISS. See El Reg

Links:

EDIT. DT-Talkie doesn't seem to work with these debs. I think its down to a change to 64-bit timestamps in the sourceforge repo. Still they may be of some use, if you want the latest code for other purposes.
liboasys deb
DTN2 deb

Considering that it can take a packet up to 20 minutes to go from Earth to Mars, you're certainly going to need some delay tolerance in your network!

NASA have their own implementation of the Bundling Protocol, called ION, which is also open source, but you have (or had) to jump through some hoops to get it. It use LTP as deep-space protocol transport, and is I believe 'kinda' interoperable with the DTN2 reference implementation. LTP is geared up for light-speed induced delays. DTN2 doesn't really offer much for deep-space work, but has support for some other interesting protocols, such as the Nack Oriented Reliable Multicast (NORM) protocol and I've been slowly knocking up support for the AX.25 protocol used by radio hams, and supported by the Linux kernel.

Ah, yes, I can see how light-speed induced delays are different than other kinds of delays. In my extreme-case example of 20 light minutes difference between nodes, the other node is online, but it takes 40 minutes to get back an acknowledgment that it received your message. That's different than the delays assumed by DTN; in "normal" cases, the other node is assumed to be offline if it doesn't acknowledge your request.

In space, there's also the predictable delays due to occlusions.

Edit - Oh, and the general case, doesn't really make assumptions about other nodes being offline. DTNs use late-binding for destination addresses, and route data incrementally towards their destination (hopefully), using a store-and-forward overlay network.

fnordianslip:

How is your dtn 2.5.1 package different than the dtn 2.6.0 package provided by the DT-Talkie group?

Ah. Its probably my lazy and old hack to the debian control file that kept the old version number. The code in my debs is hot from the forge. They also don't claim to have built against avavhi, for bonjour discovery. Mine is built and configured (as per default) to use libdb4 for its bundle store, whereas they are (perhaps wisely in a minimalist sense) using a file-system based backing store. They also would appear to have a customised dtn.conf file, whereas my dtn deb ships the stock one. I didn't actually realise they'd posted debs for the DTN2 stuff on their page too. You might be better off with their one for use with DT-Talkie as per their guide.

Is there any sign of the source for DT-Talkie? I got a binary from Tarikal ages ago, but they still don't seem to mention source on their page.