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ekos
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LBT loadbalacing over a Converged Network Adapter

We use Dell blades with a CNA installed. The CNA handles both the FC and Ethernet traffic, and presents a vmhba and vmnic to the ESX host. On the DVS we use LBT (Route based on physical NIC load). I know that LBT is based on the utilization of an uplink. When the utilization on the uplink reaches 75%, LBT will load-balance the traffic to the second uplink. But does it also take the FC traffic into account? I'm curious how does LBT work in this case?

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chriswahl
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LBT looks at Ethernet traffic traversing the dvUplink, with the 75% threshold being based on the port speed. LBT does not look at the FC vmhba traffic. It is up to your CNA to either carve up the 10Gb into unique port speeds (such as 6Gb for Ethernet and 4Gb for FC / FCoE) or provide some sort of lossless flow control to FC. In either event, LBT is solely focused on the Ethernet dvUplink saturation, not the CNA saturation.

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators

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chriswahl
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LBT looks at Ethernet traffic traversing the dvUplink, with the 75% threshold being based on the port speed. LBT does not look at the FC vmhba traffic. It is up to your CNA to either carve up the 10Gb into unique port speeds (such as 6Gb for Ethernet and 4Gb for FC / FCoE) or provide some sort of lossless flow control to FC. In either event, LBT is solely focused on the Ethernet dvUplink saturation, not the CNA saturation.

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators
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ekos
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This triggers another question: if the 10 Gb CNA is split up in 6Gb for Ethernet and 4Gb for FC / FCoE, where is 75% threshold based upon? The 6 Gb the CNA handles for Ethernet or the 10 Gb that is presented to ESXi?

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chriswahl
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Whatever the connection speed on the uplink shows in the ESXi host. If it shows 10Gb, then the value is 10Gb.

Note: most CNAs using port speed isolation will also connect at that speed (meaning the host will show a 6Gb uplink).

VCDX #104 (DCV, NV) ஃ WahlNetwork.com ஃ @ChrisWahl ஃ Author, Networking for VMware Administrators