VMware: physical switch load balancing

One of the most difficult (and almost undocument) features of ESX is to configure your switch for assisted load balancing for a VM Network vswitch with more then 1 pNICs. You should be aware of the fact that ESX supports 802.3ad Static only (EtherChannel).

In essence, you need 2 things:
1. A load balancing schema on your switch port group, based on the switch configuration. The trick here is to setup your vSwitch load balancing policy to be compatible.

• src-mac, dst-mac, src-dst-mac = MAC hash
• src-ip, dst-ip, src-dst-ip = IP hash

For Cisco catalyst switches, issue the show etherchannel load-balance command. This should result in something like src-dst-ip.

2. VLAN trunk port on your switch when using different VLANs (VST mode) for your Virtual Machines

To achive this, you need to configure your switch(example for a catalyst running on IOS creating an etherchannel for 3 pNICs):

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interface port-channel1
description VMware ESX - Trunk A
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200 (= VLANs to be assigned)
switchport mode trunk
switchport nonegotiate (=ESX does not support DTP (dynamic trunking protocol). So when you configure a trunk port, set it to nonegotiate)
spanning-tree portfast trunk
!
exit
!
interface GigabitEthernet1/1
description VMware ESX - Trunk A - NIC 0
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200 (= VLANs to be assigned)
switchport mode trunk
switchport nonegotiate (=ESX does not support DTP (dynamic trunking protocol). So when you configure a trunk port, set it to nonegotiate)
spanning-tree portfast trunk
channel-group 1 mode on
!
exit
!
interface GigabitEthernet1/2
description VMware ESX - Trunk A - NIC 1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200 (= VLANs to be assigned)
switchport mode trunk
switchport nonegotiate (=ESX does not support DTP (dynamic trunking protocol). So when you configure a trunk port, set it to nonegotiate)
spanning-tree portfast trunk
channel-group 1 mode on
exit
!
interface GigabitEthernet1/3
description VMware ESX - Trunk A - NIC 2
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 100,200 (= VLANs to be assigned)
switchport mode trunk
switchport nonegotiate (=ESX does not support DTP (dynamic trunking protocol). So when you configure a trunk port, set it to nonegotiate)
spanning-tree portfast trunk
channel-group 1 mode on
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There is however a whitepaper available on the VMware site. Download it here