Date: Wed, 26 Apr 2006 07:05:23 -0500 From: Jonathan Horne <jhorne@dfwlp.com> To: freebsd-questions@freebsd.org Subject: Re: How to verify speed of a 1Gb/s network? Message-ID: <200604260705.23623.jhorne@dfwlp.com> In-Reply-To: <274988B5-AE3C-4F97-A811-E9BC1F43A580@shire.net> References: <20060426031606.33136.qmail@web33302.mail.mud.yahoo.com> <274988B5-AE3C-4F97-A811-E9BC1F43A580@shire.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tuesday 25 April 2006 23:17, Chad Leigh -- Shire.Net LLC wrote: > 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 a few years back, i had a gigabit fiber switch, and 2 intel gigabit fiber cards that i put in my 2 fastest computers (at the time, dual p3 1000 and dual p3 933). they both had 10k rpm ultra160 SCSI drives. the fastest i could get for continuous transfer (i made some gigantic zip files containing several .iso files) was about 250mbit. jonathan
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200604260705.23623.jhorne>