Date: Sun, 20 Dec 2009 17:17:41 +0100 From: Roland Smith <rsmith@xs4all.nl> To: Anton Shterenlikht <mexas@bristol.ac.uk> Cc: freebsd-questions@freebsd.org Subject: Re: debugging slow network Message-ID: <20091220161741.GA19596@slackbox.xs4all.nl> In-Reply-To: <20091220132250.GA94754@mech-cluster241.men.bris.ac.uk> References: <20091220132250.GA94754@mech-cluster241.men.bris.ac.uk>
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--xHFwDpU9dbj6ez1V Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Dec 20, 2009 at 01:22:50PM +0000, Anton Shterenlikht wrote: > I seem to have a very slow network connection at work. > All local switches are supposed to be gigabit, and my > network card is gigabit as well. But download speed > seems to be much lower. Are we talking download from the internet, or from the local network? Every time you connect to a server on the internet, your packets travel through a chain of hosts, routers and switches. And as with any chain, the weakest (in this case slowest) link determines the strength (speed) of the chain. Which is unlikely to be your internal gigabit network, unless someth= ing is misconfigured on your end. So it could be that you are expecting too muc= h. If you are experiencing slow speeds on the internal network, contact the network admin and ask for help. But make usre that your network hardware is set up correctly. =20 > I'm not a networks person, but I understand there could > many factors affecting the speed.=20 Definitely. > There appear to be > a multitute of different network related commands > just in base OS. Which should I start with to get > some idea of the actual network speed? netstat? > And should I be looking for? =20 As usual, the answer is probably; it depends on what is causing the slow sp= eed. If the problem is not caused by hardware or software problems on your machi= ne, you cannot do very much about it by yourself. You need at least the help of= your network admin. I would start with the ifconfig command. This will show you how your network hardware is configured. It should list at least two devices, and you should= =20 ignore one of them, lo0. Look for the lines starting with a lot of spaces a= nd then 'media:'. That should tell you how your ethernet hardware is configured. If= it is running at gigabit speed, you should see something like; media: Ethernet 1000baseTX <full-duplex> If it shows 100baseTX or 10baseT/UTP, you're not getting a gigabit connecti= on but 100 or 10 Mbits/s. Also look through /var/log/messages for any logged messages from your ether= net hardware.=20 In my experience a lot depends on the quality of the network hardware and t= he drivers. On a 100 Mbit/s point-to-point connection, I've observed throughput of up to 10 Mbyte/s (12,5 would be the theoretical maximum). This was betwe= en two xl(4) devices. If one of the devices is an rl(4) device, the maximum throughput speed I've seen is about 4 Mbyte/s (using the same cable and hardware on the other end). Roland --=20 R.F.Smith http://www.xs4all.nl/~rsmith/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 1A2B 477F 9970 BA3C 2914 B7CE 1277 EFB0 C321 A725 (KeyID: C321A725) --xHFwDpU9dbj6ez1V Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) iEYEARECAAYFAksuTiUACgkQEnfvsMMhpyUNsQCghVprEFQN1xuCHG7/pc4wVGl+ Rj4AnRjsbG3Cc/HUkbb2K8mqV7Lj8ICG =ug/r -----END PGP SIGNATURE----- --xHFwDpU9dbj6ez1V--
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