Why am i getting 1Gbps speeds on 10Gbps links?

asked 2021-12-17 15:29:23 +0000

SysAdminUnknown gravatar image

Hello everyone,

I have an Aruba Switch with 10Gbps interfaces, and two esxi servers with 10gbps nics connected to the aruba with cat6 ethernet cables. Using iperf3 between two virtual machines im getting around 1Gbps. I will attach a Wireshark capture that show the iperf3 connection from start to end.

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Are you running TCP or UDP?

BigFatCat gravatar imageBigFatCat ( 2021-12-17 22:42:43 +0000 )edit

Im running TCP.

SysAdminUnknown gravatar imageSysAdminUnknown ( 2021-12-17 23:15:44 +0000 )edit

Can you check if the TCP window is large enough?

BigFatCat gravatar imageBigFatCat ( 2021-12-18 07:47:04 +0000 )edit

If you use ethtool. What do you get as negotiated speed? If you put both VM's on the same server. What throughput speed do you get? You are not likely to get anything better with 2 ESXi hosts.

hugo.vanderkooij gravatar imagehugo.vanderkooij ( 2021-12-20 13:41:08 +0000 )edit

Hello, i came back to office today, and i checked the TCP Windows, its 65535.

I move the two VMs to the same host and using Iperf3 im getting 2 Gbps speed. This means that my bottleneck is at the esxi level? should i replace the ESXi hosts with new servers?

SysAdminUnknown gravatar imageSysAdminUnknown ( 2021-12-20 18:54:53 +0000 )edit
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