Date: Thu, 22 Nov 2001 17:41:08 +0800 From: francisv@dagupan.com To: ryan@sasknow.com Cc: freebsd-questions@FreeBSD.ORG Subject: RE: Maximizing throughput Message-ID: <10F29E27A956D511B0940050DA8D86A9340BE9@apmail.dagupan.com>
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Thank you, Ryan, for the detailed response. Please see my comments below: -----Original Message----- From: Ryan Thompson [mailto:ryan@sasknow.com] Sent: Thursday, November 22, 2001 5:31 PM To: francisv@dagupan.com Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Maximizing throughput francisv@dagupan.com wrote to freebsd-questions@FreeBSD.ORG: > Hi, > > I have an Intel Pro 100/S NIC on FreeBSD 4.4-STABLE -- > transferring huge (~650MB) files to another computer is only > around 1.78Mbps. The machines are connected via a Cisco 3500XL > switch at full-duplex, 100Mbps. Is there any other way to increase > the throughput or is this the actual bandwidth limit? 1.78Mbps is pretty abysmal for a 100Mbps link. There are a lot of factors which may be causing this. I'm guessing (correctly, I bet) that it is NOT a configuration issue with FreeBSD, unless prior to this, you were messing with network settings that you shouldn't have. :-) So, I don't have an answer for you, but I'll take you through some troubleshooting that will probably get to the root of the problem fairly quickly. For rates that low, packets are almost certainly getting dropped. My first wave of questions goes something like this, 1. What application layer protocol is being used to transfer? FAV> FTP 2. Does it run over TCP or UDP? FAV> TCP 3. Are you using CAT5 cabling between both hosts and the switch? FAV> Yes, we're using category 5 UTP cable on both hosts; less than 5 feet FAV> per host to the switch 4. How loaded are the machines? The switch? FAV> Between 5-10 percent load 5. How did you calculate your "speed" statistic? Are you sure? FAV> I don't know if the throughput display (after uploading) of the FTP FAV> client is in megabytes or megabits; I'm guessing it's in megabytes, not FAV> megabits. From my MRTG graph, it used a maximum of 15.6 megabits -- FAV> is this the actual throughput limit? 6. Are there any routers between the two hosts? FAV> No, there are no routers in between Things to try: Connect the machines directly with crossover cable, or connect them to a hub. Run tcpdump on one of the machines (or another host on the same segment) and look for any weirdness. As for possible causes/remedies, it's hard to say at this point. Like I said, one of your likely symptoms is dropped packets. This could happen at just about any layer. Maybe your cabling is poor grade (or there is too much EMI), causing Ethernet frames to get dropped. Maybe one of the hosts (or the switch) is configured wrong. Maybe your transfer application is broken. Maybe one of your network cards needs to be replaced. Maybe one of your cables is defective. So, as for increasing the bandwidth limit, you'll need to fix whatever is slowing things down. :-) Hope this helps, - Ryan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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