Hi, I have 2 servers running CentOS 6.3. Each has four 1gb Ethernet ports. I have bonded all four ports on each server and patched them to the same switch (following the instructions at http://wiki.centos.org/TipsAndTricks/BondingInterfaces). I have created aggregated trunks for the servers respective ports on the switch. The switch reports that the ports are up and that the Link Aggregation is enabled. I was under the impression, perhaps falsely, that I would see an improvement in the throughput. I am not sure that I am. I used a utility call nuttcp before the trunking and after to test the throughput. I am seeing miniscule differences in the Mbps. I am not sure that I am testing correctly. Perhaps the speed will not change but the available bandwidth has increased. Is there some way to demonstrate that I am able to transfer data from these two servers at a rate of 4,000Mbs? Does anyone have any thoughts? I pasted some details below increase they have a bearing. Thanks in advance Dermot. ./nuttcp otherserver 1125.6573 MB / 10.03 sec = 941.4967 Mbps 10 %TX 47 %RX cat /proc/net/bonding/bond0 Ethernet Channel Bonding Driver: v3.6.0 (September 26, 2009) Bonding Mode: IEEE 802.3ad Dynamic link aggregation Transmit Hash Policy: layer2 (0) MII Status: up MII Polling Interval (ms): 100 Up Delay (ms): 0 Down Delay (ms): 0 802.3ad info LACP rate: slow Aggregator selection policy (ad_select): stable Active Aggregator Info: Aggregator ID: 2 Number of ports: 4 Actor Key: 17 Partner Key: 420 Partner Mac Address: 10:0d:7f:4c:16:ca Slave Interface: eth0 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 2c:76:8a:5d:28:1c Aggregator ID: 2 Slave queue ID: 0 Slave Interface: eth1 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 2c:76:8a:5d:28:1d Aggregator ID: 2 Slave queue ID: 0 Slave Interface: eth2 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 2c:76:8a:5d:28:1e Aggregator ID: 2 Slave queue ID: 0 Slave Interface: eth3 MII Status: up Speed: 1000 Mbps Duplex: full Link Failure Count: 0 Permanent HW addr: 2c:76:8a:5d:28:1f Aggregator ID: 2 Slave queue ID: 0