Hi, On Tue, 08 Feb 2005 08:18:35 -0600, Jeffrey C. Ollie wrote:
> On Tue, 2005-02-08 at 12:59 +0200, Paul Ionescu wrote: >> >> On Sun, 06 Feb 2005 14:07:20 +0200, Paul Ionescu wrote: >> > >> > Every X seconds we send a special frame on the wire, the destination >> > address is our own MAC address of that interface, which means that we >> > are the end destination of that packet. The ether-type can be 0x9000 >> > which is >> > registered for loopback packets. >> > If the link is up, we should receive this packet because it has our >> > own mac address as destination, which will be reflected in rx_packets >> > counter. Now, if we miss Y packet in a row, we could assume the link >> > is off. >> >> I actually did some further test, and so far I like what I found. I used >> only ready available tools (like ping) because I did not have time to do >> some real programs. >> [...] >> I did "ping -b 10.1.1.255" >> [...] >> Comments ? I did ping -b only to test the logic. Of course I don't want to use it in a normal network. I just did not had any knowledge of a quick hack to send that loopback packet on the wire. > > Using "ping -b" itself would be bad, very bad on large networks. Just > imagine the effect of a broadcast ping on a network of several hundred or > several thousand hosts (large corporate, government, or educational > networks or cable modem networks). Sending out a specially crafted > ethernet packet with our own ethernet address as the destination would > probably be fine, assuming the kernel would actually send it out the wire > and wouldn't short circuit the transmission. > > In fact, looking at a dump of my network it looks like I have a Cisco > system out there doing a similar thing: Yes, some cisco equipment does this. _______________________________________________ NetworkManager-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/networkmanager-list
