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I have two ESXi 6 hosts. They each have dual 10GB NIC's. There are two cables connecting the servers together directly. (These NIC's are for vmotion and management stuff only.) I configured a vswitch with both NIC's as uplinks in teaming mode, and attached a vmkernel adapter to it.

I have two questions.

1) Am I getting any performance benefit from having the NIC's teamed? This question is specific to link aggregation following the 802.11ad standard, but it suggests that when there are only two hosts direct cabled like this, only one link will actually be used: https://unix.stackexchange.com/a/33723 (I don't not know how vmware's link aggregation works.)

2) Could this cause weird network issues? (Since each NIC in the team can only see one other NIC. Sender would have to know when addressing HOST1NIC1 send packet over HOST2NIC1, but when addressing HOST1NIC2 send packet over HOST2NIC2. I could imagine software assuming HOST1NIC1 is accessible from both HOST2NIC1 and HOST2NIC2 and vice versa.)

  • Are you having a specific problem with throughput? I don't recommend teaming in VMware unless you're running LACP and distributed switches. – ewwhite Sep 23 '16 at 21:19
  • I'd like to be able to vmotion multiple large VM's in parallel more quickly. Why do distributed switches and LACP make teaming a better option? – FullTimeCoderPartTimeSysAdmin Sep 23 '16 at 21:42
  • What do you mean "large" VMs? Are you talking about vMotion between hosts or storage devices? Also, with only 2 hosts you can never vMotion more than 8 VMs at a time per vmware.com/pdf/vsphere6/r60/… – D34DM347 Oct 26 '16 at 12:10
  • By "large," I mean that their virtual disks are large-ish (~1 TB). I'm vmotioning them from local storage on host to local storage on another. – FullTimeCoderPartTimeSysAdmin Oct 26 '16 at 17:36
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In answer to your first question sort of.

A single network stream is still limited to 10Gbit/s as the load balancing hash is based on either mac or ip addresses at both ends. This means in the case of multiple connections you will get overall 20Gbit/s.

  • There are only two systems involved (directly cabled together). Will there be the multiple connections I need to use the full 20Gbit? (If the load balancer is assigning link based on a hash of the ips involved in a connection, for example, it seems like it would assign all traffic to the same link.) – FullTimeCoderPartTimeSysAdmin Sep 23 '16 at 21:43
  • You are correct, there are ways to solve this with multiple IPs but unless you think you are going to need 20Gbit/s then I'd stick with active passive failover. – Tim Fletcher Sep 23 '16 at 22:02

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