On Jan 4, 2006, at 12:19 PM, Eric Wilson wrote: > I thinkg we'd need to see many interations oscilating between name > vs IP, > to make a reasonable conlusion. > > Effectively any one single packet could have taken significanlty > longer.
Yes, it could. Except that I was looking at the round-trip time (rtt) stats, too. For the IP ping the average rtt was 0.332. So, the total rtt for all 1000 packets was 332ms. I imagine the difference between 332ms and the total time of 383ms (i.e. 51ms) is due to other tasks. For the name ping the average rtt was 0.100ms. So, the total rtt for all 1000 packets was 100ms. That means that for about 24 seconds (24598ms-100ms) ping was doing something other than sending/receiving ping packets. In fact, even if all 1000 packets took the maximum rtt of 0.133ms, that would still be a total rtt of 133ms. BTW, my knowledge of the rtt stats is from what I've read in the man page, so it is possible that I'm not interpreting rtt stats correctly. > pinging localhost v 127.0.0.1 my also eliminate extranious > anomilies too. Good idea: $ ping -f -c 1000 127.0.0.1 PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data. --- 127.0.0.1 ping statistics --- 1000 packets transmitted, 1000 received, 0% packet loss, time 82ms rtt min/avg/max/mdev = 0.026/0.028/0.098/0.007 ms, ipg/ewma 0.082/0.028 ms $ ping -f -c 1000 localhost PING localhost.localdomain (127.0.0.1) 56(84) bytes of data. --- localhost.localdomain ping statistics --- 1000 packets transmitted, 1000 received, 0% packet loss, time 785ms rtt min/avg/max/mdev = 0.029/0.036/0.111/0.010 ms, ipg/ewma 0.786/0.037 ms Same phenomenon: name takes longer than IP. The rtt's are comparable but the times differ by an order of magnitude. I'm assuming that time can be less than total rtt because ping is sending packets without waiting for them to return. > I thing ping v name vs ping v IP is only an anomily. I dunno. Seems to be a pretty consistent anomoly. >> What's wrong with this picture? >> >> Notice the time if I ping a machine by IP address: >> >> $ ping -f -c 1000 10.4.0.4 >> PING 10.4.0.4 (10.4.0.4) 56(84) bytes of data. >> --- 10.4.0.4 ping statistics --- >> 1000 packets transmitted, 1000 received, 0% packet loss, time 383ms >> rtt min/avg/max/mdev = 0.086/0.332/29.934/2.000 ms, pipe 2, ipg/ewma >> 0.384/3.827 ms >> >> Now, notice the time if I ping by name: >> >> $ ping -f -c 1000 foo >> PING foo.com (10.4.0.4) 56(84) bytes of data. >> --- foo.com ping statistics --- >> 1000 packets transmitted, 1000 received, 0% packet loss, time 24598ms >> rtt min/avg/max/mdev = 0.092/0.100/0.133/0.010 ms, ipg/ewma >> 24.622/0.100 ms Regards, - Robert http://www.cwelug.org/downloads Help others get OpenSource software. Distribute FLOSS for Windows, Linux, *BSD, and MacOS X with BitTorrent _______________________________________________ CWE-LUG mailing list [email protected] http://www.cwelug.org/ http://www.cwelug.org/archives/ http://www.cwelug.org/mailinglist/
