Date: Tue, 25 Apr 2006 22:17:44 -0600 From: "Chad Leigh -- Shire.Net LLC" <chad@shire.net> To: Rob <spamrefuse@yahoo.com> Cc: freebsd-questions@freebsd.org Subject: Re: How to verify speed of a 1Gb/s network? Message-ID: <274988B5-AE3C-4F97-A811-E9BC1F43A580@shire.net> In-Reply-To: <20060426031606.33136.qmail@web33302.mail.mud.yahoo.com> References: <20060426031606.33136.qmail@web33302.mail.mud.yahoo.com>
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On Apr 25, 2006, at 9:16 PM, Rob wrote: > Hi, > > How can I verify that a 1Gb/s network is indeed > operating at its optimal speed? I tried this: > > [master]$ ping -s 65507 node > 65515 bytes from node: icmp_seq=0 ttl=64 time=1.97 ms > 65515 bytes from node: icmp_seq=1 ttl=64 time=1.95 ms > 65515 bytes from node: icmp_seq=2 ttl=64 time=1.94 ms > 65515 bytes from node: icmp_seq=3 ttl=64 time=1.97 ms > > (I tried many times, over a long period of time > to get these typical values). >> From this I conclude that it takes about 1.95 ms > for 65515 x 8 bits to go forth and back between > master and node. > > Ideally, on a 1Gbit/s network, the time should be: > 65515 x 8 x 2 / (10243) = 0.98 ms > (x 2 for the roundtrip signal forth and back > and 10243 is the 1G of the network) > > May I now conclude that the real-time is about > two times the ideal-time? I wonder if this indicates > a problem of the network? > And is this a proper test of this Gbit/s network? > > Thanks, > Rob. > > PS: I verified my calculation method for two > computers here on a 100Mbit/s network, from which > I get: > time with ping: 12.4 ms > ideal calculated time: 10 ms > which is an acceptable difference I would suspect that a ping is not a valid test as it does not test throughput and the send and reception phases have a large influence on the out come. Ie, the time for the send and reception to take place is long enough compared to the fast network that the results are skewed. Try an ftp or other non-encrypted data transfer with a large enough file that the startup and wind-down won't affect and skew it. Probably still not a definitive test btw, here is a test of my gbit network using your ping test 15 packets transmitted, 15 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.128/0.227/0.342/0.061 ms --- Chad Leigh -- Shire.Net LLC Your Web App and Email hosting provider chad at shire.net
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