Hi there, On Fri, 25 Jul 2008, Jim Long wrote:
> IANA statistician, nor am I a smokeping guru, but... Sometimes you can get carried away with satistics. After all, it was said "there are lies, damned lies, and statistics"... ;) I'd be very reluctant to translate one lost packet PER MINUTE out of five (or four out of twenty) as 20% packet loss, when the packets I'm measuring are 56-byte UDP pings and there are probably tens of thousands of 1.5kByte TCP packets (mostly SMTP and HTTP in my case) passing PER SECOND over the same routes at the same time. I think that the effective TCP loss is zero, as all the nightly backups that I do (they range from about a hundred megabytes to some tens of gigabytes after compression by bzip2 or gzip) make it in tact to the backup servers. I don't have a good handle for the numbers of TCP retransmissions, nor of how much rsync has to do on top of that; if I thought there might be a problem that's where I'd look next. None of this will be constant even over a short timescale: a quick Google for "tcp congestion algorithm" (without the quotes) gave me about 338,000 hits. In the case of your network, the best thing to do is probably what you find works best for you. Only you can know how your network is being used, and what is appropriate for one network might not be relevant to another. For example I'm using a lot of different probes (UDP pings, DNS pings, TCP pings for SSH and HTTP) from a few different machines to a lot of other machines; my graphs are all on logarithmic scales; and now I've got it mostly buttoned down I don't look at the graphs as often as I used to. I've started to remove the debug logging. That's because I've thought about what the networks are doing, taken a view on what I need from the tools, and now I think I've got it, I'm happy. I wouldn't presume to say that what I've done would be the 'best' way of doing it, even supposing I had any idea what that might be, but It Works For Me. Thanks again, Tobi, BTW. :) -- 73, Ged. _______________________________________________ smokeping-users mailing list [email protected] https://lists.oetiker.ch/cgi-bin/listinfo/smokeping-users
