LACP bonding with 2 x10G nic are giving 10G traffic only


May 5, 2022

We have 2 servers. each of them has 2 x10G interface. We have created bond interface with 2 x10G nics and connected 2 servers. But we are getting only 10G throughput. Not 20gbps. What are we missing in the configuration? In future we can only use LACP. not other protocols, Because we shall connect these servers with a switch supporting the LACP only.


The output we are getting only 10gbps. Not 20gbps.

Thanks in advanced.
You need at least two parallel connections.
Try iperf with parameter -P 2 (or higher) again.
Still getting 10gbps. Used the command:

server end: iperf -s
client end: iperf -c -i 1 -t 3000 -P 5

If I configure LACP at the switch's end and configure balance-rr at Proxmox's end, will the switch support this?
Oh no, sorry, on your diagram was no switch. balance-rr only works with a direct connection.
You can try to test LACP with two "iperf -s -p <PORT>" Different Server instances in parrallel.
Hey bsinha,

you configured your LACP-Bond with Layer2 Hash Policy. Thus the transferred traffic is split according to the source- and target MAC adresses. Even though you are using multiple instances of iperf, the MAC adresses involved do not change and LACP considers it as one session (and transfers the data all over the same interface), yielding 10Gbit.

You can try to change the Hash Policy to Layer3+4, then the traffic is split according to IP adresses and Port numbers. Running multiple instances of iperf should give each instance an own source port and split the traffic.

Other than that, if you stick to the Layer2 hashing, it would work if the MAC adresses differ, e.g. if you put up multiple VMs and run iperf simultaneously on each VM.

Kind regards,
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