Sample switch port configuration for VLAN and TRUNK MODE

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

This article describes VLAN and TRUNK MODE configuration concepts of VST.

Note: VMware recommends utilizing VLAN technology to establish dedicated subnets for ESX/ESXi management, VMotion, and iSCSI network traffic.

Only allowing through VLAN traffic on physical switch ports connecting to ESX reduces TCP/IP overhead. Native VLANs do not tag the out going VLAN packets toward ESX NICs and if the same VLAN ID is used to configure the vSwitch port group, the vSwitch drops any packet that is not tagged for it, causing the connection to fail. Unnecessary VLAN traffic on a TRUNK port that connects to ESX can cause major performance issues.

Note: Do not use the Native VLAN ID of a physical switch as a VLAN on ESX/ESXi portgroups.

Symptoms:

Case1
When testing network connection using the ping command, the response fails with the following nodes:

• Gateway IP address
• VLAN gateway IP address
• Host on the same subnet or other subnets are not able to ping each other

Case2
Traffic doesn't go through for sometime during ESXi boot-up, however it later normalizes   

From vmkernel:
2021-07-29T13:09:36.314Z cpu10:2097715)TeamCheck: NTCCheckResult:962: Please check connectivity on DvsPortset-0!
2021-07-29T13:10:36.315Z cpu10:2097715)TeamCheck: NTCCheckResult:962: Please check connectivity on DvsPortset-0!
2021-07-29T13:11:36.315Z cpu10:2097715)TeamCheck: NTCCheckResult:962: Please check connectivity on DvsPortset-0!

Resolution

This is a Cisco Switch port TRUNK sample configuration.

Apply the following commands to Cisco Switch command line:

• interface GigabitEthernet1/1
• description VMware ESX - Trunk A - NIC 0 – Port Description
• switchport trunk encapsulation dot1q – ESX only supports dot1q and not ISL
• switchport trunk allowed vlan 100,200 – Allowed VLANs
• switchport mode trunk – Enables Trunk
• switchport nonegotiate – ESX/ESXi does not support DTP dynamic trunking protocol. When configuring trunk port, set it to nonegotiate.
• spanning-tree portfast trunk – Enables PortFast on the interface when it is in trunk mode.

Sample of ESX vSwitch configuration for VST mode:

• esxcfg-vswitch [options] [vswitch[:ports]]
• esxcfg-vswitch -v [VLANID] -p [port group name] [vswitch[:ports]]
• esxcfg-vswitch -v 200 -p "Virtual Machine Network 2" vSwitch1

Additional Information

To configure an ESX Virtual Switch with VLAN ID or VST mode see:

• Sample configuration of virtual switch VLAN tagging (VST Mode)
• Troubleshooting network connectivity with Virtual Switch Tagging (VST) / External Switch Tagging (EST) mode on an ESX/ESXi host

Sample configuration of virtual switch VLAN tagging (VST Mode)
Troubleshooting network connectivity with Virtual Switch Tagging (VST) / External Switch Tagging (EST) mode on an ESX/ESXi host