From mboxrd@z Thu Jan 1 00:00:00 1970 From: William Xu Date: Thu, 25 Oct 2007 18:20:43 +0000 Subject: Re: [LARTC] TC (HTB) doesn't work well when network is congested? Message-Id: <4720DE7B.10404@max-t.com> List-Id: References: <4720C673.7040900@max-t.com> In-Reply-To: <4720C673.7040900@max-t.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lartc@vger.kernel.org Thanks, Peter, So what you means is that network congestion caused my problem. I test the bandwidth between client1 and server using iperf, SEND and RECV are both 122MB/s. I tried different values for the total bandwidth, and I got the following numbers: total bandwidth 120MB/s client1 SEND :10MB/s RECV :39MB/s total bandwidth 110MB/s client1 SEND :16MB/s RECV :40MB/s total bandwidth 100MB/s client1 SEND :30MB/s RECV :38MB/s total bandwidth 90MB/s client1 SEND :39MB/s RECV :40MB/s total bandwidth 80MB/s client1 SEND :39MB/s RECV :40MB/s total bandwidth 70MB/s client1 SEND :40MB/s RECV :40MB/s total bandwidth 60MB/s client1 SEND :40MB/s RECV :40MB/s So TC works well as long as total bandwidth is below 90MB/s, which is about 70% of the wise speed. Is it possible that I can use the full bandwidth (122MB/s) in my script? william Peter Rabbitson wrote: > William Xu wrote: > >> Hi, >> >> I have a server and ten clients in a Gigabit network. The server has >> 125mbps network bandwidth. >> I want that the server has 40Mbps bandwidth reserved for client 1 (IP >> 192.168.5.141), and the >> rest bandwidth is for all other clients. >> >> >> >> I ran a test in which all 10 clients send/receive packets to/from the >> server simultaneously. But >> Client 1 only got 20mbps bandwidth for sending, and 38mpbs for >> receiving. If I limit the rate of >> both classes 1:1 to 60mbps instead of 125mbps, Client 1 got 39mbps >> for sending, and 40mbps for >> receiving. >> >> I am not sure what might cause this. Is it because TC doesn't work >> well when network is congested? >> Or my script is not right? >> > > No network will be able to operate at its theoretical maximum. In the > case of a gigabit network you will be lucky to get consistent 120mbps, > and it heavily depends on the hardware quality, and the number of > switches in between. So what you are doing is oversaturating the link, > the ACK packets can not get through, your speed drops due to > delays/retransmissions. Perform a test with only two systems sending > stuff to each other to see what is the actual bandwidth you can hope > for, and use that number instead of 125mbps. _______________________________________________ LARTC mailing list LARTC@mailman.ds9a.nl http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc