On Thu, 2011-04-07 at 16:26 +0200, Fabio DellaCorte wrote: > Hello everybody , > i'm tryng to use two network device for improving performance as > describe > in http://wiki.debian.org/Bonding and > http://www.debianadmin.com/linux-ethernet-bonding-configuration.html . > I have two problem : > > > 1)I don't see performance increase trying with ftp > 2) i have used round roubin balance in in the first test and now with > balance-alb but i still see in /sys/class/net/bond0/bonding/mode > "balance-rr 0" > <snip> There are a couple of issues in bonding which can bite the unsuspecting (as they did me!). Round robin will load balance across multiple interfaces but can produce serious issues with managing out of order TCP packets. Thus, the performance gain decreases dramatically with the number of interfaces. In other words, 2 NICs in RR mode will not give 2x the performance nor 3 NICs 3x performance. I do not recall the exact numbers off the top of my head but averages are something like: 2 NICs - 1.6x performance 3 NICs - 1.9x performance
The other modes (other than failover) eliminate the out of order TCP problem but do so at a cost. All traffic for a single traffic flow goes across a single path. The most common way to identify a single traffic flow is matching source and destination MAC addresses. Some bonding algorithms allow matches on layer 3 or even layer 4 data but, if the switch through which they flow only supports MAC to MAC flow assignments, it will all devolve to matching MAC addresses anyway. So what is the practical outcome using non-RR bonding? You have only one combination of source and destination MAC address for each socket, e.g., if you are measuring a single FTP connection, there is only one combination of source and destination MAC address. Thus, no matter how many NICs you have, all the traffic will flow across one combination of NICs. You will see no performance improvement. In fact, depending on how the MAC addresses are advertised from the systems with multiple NICs, all traffic between two systems may flow across the same pair of NICs even if there are multiple, different traffic streams. On the other hand, if you are using bonding to provide a trunk carrying traffic from many different source and destination MAC address combinations, each separate stream will be limited to the maximum of the individual NICs but the aggregate throughput should increase almost linearly with the number of NICs. Hope that helps - John -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/1302199755.18179.18.ca...@denise.theartistscloset.com
