[sugar] Ad-hoc Networking
Thu Apr 24 04:51:57 EDT 2008
On Thu, Apr 24, 2008 at 1:27 AM, John Gilmore <gnu at toad.com> wrote:
> Take two such laptops.
> Take them way out into the country so they can only communicate with
> each other.
> There are no access points. No laptop is acting as an access point, either.
> Can those two laptops communicate? Under 802.11b/g, the answer is yes.
> They are communicating in "ad-hoc" mode. Each can transmit packets and
> the other one gets the packets. (This works for N laptops, not just two.)
> The IETF "ZeroConf" protocols provide for self-assignment of IP
> addresses in such a case. (The same thing happens if you plug two
> laptops together with a short Ethernet cable and no DHCP server.)
> Once they self-assign IP addresses, the laptops can talk at an IP
> level. They can send unicast, multicast, and broadcast packets to
> each other. (If you look in the Mac Control Panel, you'll see this
> reported as a "self-assigned IP address", with a warning that you
> probably aren't connected to the global Internet, since most of the
> time that was what you probably expected.)
> Does the OLPC Presence Service work in such a case?
Yes, that is exactly what telepathy-salut does, using avahi. You can
also take two Nokia N800s and chat between them, or two laptops at a
conference running a telepathy-based jabber client like Empathy, and
chat between them - all ad-hoc, no infrastructure required.
More information about the Sugar-devel