VCAP6: 3.4 - Troubleshoot a vSphere 6.x Network Implementation

Objective 3.4 Topics:

Perform a vDS Health Check for Teaming, MTU, mismatches etc…
Configure Port Groups to Properly Isolate Network Traffic
Use Command Line Tools to Troubleshoot and Identify Configuration Issues
Use Command Line Tools to Trouble and Identify VLAN Configurations
Use DCUI Network Tool to Correct Network Connectivity Issues

Perform a vDS Hath Check for Teaming, MTU, Mismatches etc…

The health check support in vSphere Distributed Switch 5.1 and later helps you identify and troubleshoot configuration errors in a vSphere Distributed Switch.

vSphere runs regular health checks to examine certain settings on the distributed and physical switches to identify common errors in the networking configuration. The default interval between two health checks is 1 minute.

Checks:

VLAN trunk ranges on dVS match that on the physical switch
MTU settings on vDS and physical switch match
Teaming policy on port groups match that of the port-channel on the physical switch

Enable/Disable Health Check on the Distributed Switch

View Distributed Health Status

My teaming and Failover shows as unknown since the vDS’s aren’t connected to a physical switch, since this is a nested environment.

Use Command Line Tools to Troubleshoot and Identify Configuration Issues

Linux commands for retrieving networking information are not included in the ESXi Shell. You can instead use ESXCLI commands

On ESXi 5.0 and later, ifconfig information is the information for the VMkernel NIC that attaches to the Management Network port group.

Retrieve Network Information

Information on our vmkernels

IP information on a specific vmkernel

Information on a IP 6 on a vmkernel

Information on IP 6 addresses.

Retrieve Information about DNS

Information on the search domain

Information on the DNS servers used

Information on the connections

Retrieve Information on the vSwitch Configuration and VMkernel interfaces

Add/Remove Network Cards (vmnics) to/from a Standard Switch

esxcli network vswitch standard uplink remove –uplink-name=vmnic –vswitch-name=vSwitch # unlink an uplink

esxcli network vswitch standard uplink add –uplink-name=vmnic –vswitch-name=vSwitch # add an uplink

Add/Remove Network Cards (vmnics) to/from a Distributed Switch

esxcfg-vswitch -Q vmnic -V dvPort_ID_of_vmnic dvSwitch # unlink/remove a vDS uplink

esxcfg-vswitch -P vmnic -V unused_dvPort_ID dvSwitch # add a vDS uplink

Remove an Existing VMkernel port on vDS

esxcli network ip interface remove –interface-name=vmkX

Note: The vmk interface number used for management can be determined by running the esxcli network ip interface list command.

Create new Standard Switch and Port Group

esxcli network vswitch standard add –vswitch-name=vSwitch

esxcli network vswitch standard portgroup add –portgroup-name=portgroup –vswitch-name=vSwitch

Create VMkernel port and Attach it to a Port Group

esxcli network ip interface add –interface-name=vmkX –portgroup-name=portgroup

esxcli network ip interface ipv4 set –interface-name=vmkX –ipv4=ipaddress –netmask=netmask –type=static

To set a VLAN ID we can run the following command:

esxcli network vswitch standard portgroup set -p portgroup –vlan-id VLAN

We might need to restart the management agents if network connectivity is not working. services.sh restart

Use Command Line Tools to Troubleshoot and Identify VLAN Configurations

Setting the Port Group VLAN ID

A VLAN ID restricts port group traffic to a logical Ethernet segment within the physical network.

Set the VLAN ID to 4095 to allow a port group to reach port groups located on other VLAN.
Set the VLAN ID to 0 to disable the VLAN for this port group.

Allow port groups to reach port groups located on other VLANs

esxcli <conn_options> network vswitch standard portgroup set -p <pg_name> –vlan-id 4095

Disable VLAN for Port Group

esxcli <conn_options> network vswitch standard portgroup set –vlan-id 0 -p <pg_name>

Host Networking Rollbacks

Host networking rollbacks occur when an invalid change is made to the networking configuration for the connection with vCenter Server.

Below is a list of changes that could trigger a rollback: