[CentOS] Bonded interfaces - testing

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