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Sample switch port configuration for VLAN and TRUNK MODE

Symptoms

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

Purpose

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

Note: VMware recommends utilizing VLAN technology to establish dedicated subnets for ESX/EXI 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/EXi portgroups.

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:

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