With kernel 2.6.13.4 linux bridge with traffic management for 4000users and 20.4 MB/s(tx)/22.4 MB/s(rx) data load of CPU is max 50% With kernel 2.6.15.1 the same linux bridge with the same traffic has 100% CPU load and in top I have ksoftirqd proccess. The machine is P4 3.2 GHz with 1GB of ram and 4 NetGear 620 cards The config is: /sbin/modprobe acenic link=0x0100,0x0100,0x0100,0x0100 tx_coal_tick=256,256,256,256 rx_coal_tick=256,256,256,256 max_rx_desc=512,512,512,512 max_tx_desc=512,512,512,512 /sbin/ifconfig eth0 0.0.0.0 txqueuelen 10000 mtu 1500 up /sbin/ifconfig eth1 0.0.0.0 txqueuelen 10000 mtu 1500 up /sbin/ifconfig eth2 0.0.0.0 txqueuelen 10000 mtu 1500 up /sbin/ifconfig eth3 0.0.0.0 txqueuelen 10000 mtu 1500 up #To bond0 /sbin/ifconfig eth0 down /sbin/ifconfig eth2 down #To bond1 /sbin/ifconfig eth1 down /sbin/ifconfig eth3 down modprobe bonding max_bonds=2 ifconfig bond0 0.0.0.0 up ifenslave-2.6 bond0 eth0 eth2 ifconfig bond1 0.0.0.0 up ifenslave-2.6 bond1 eth1 eth3 /usr/local/sbin/brctl addbr br999 /sbin/vconfig add bond0 999 /sbin/vconfig add bond1 999 /sbin/ifconfig bond0.999 up /sbin/ifconfig bond1.999 up /usr/local/sbin/brctl addif br999 bond0.999 /usr/local/sbin/brctl addif br999 bond1.999 /sbin/ifconfig br999 up Host has 102 vlans (bridges) On each vlan interface is traffic management (iproute2 with hashing filters)