VCAP-DCA 5 Objective 2.4–Administer vNetwork Distributed Switch Settings

Objective 2.4 – Administer vNetwork Distributed Switch Settings

For this objective I used the following resources:

  • VMware KB Article 1022312
  • VMware KB Article 1010555
  • VMware YouTube Channel
  • VMware Network I/O Control: Architecture, Performance and Best Practices White Paper
  • VMware & Cisco Virtual Networking Features of the VMware vNetwork Distributed Switch and Cisco Nexus 1000V Switches
  • VMware & Cisco DMZ Virtualization Using VMware vSphere 4 and the Cisco Nexus 1000V Virtual Switch
  • VMware Networking Blog
  • Geeksilver’s Blog
  • Trainsignal Blog


Describe the Relationship Between vDS and the VSS

vDS is short for “vNetwork Distributed Switch” and VSS is short for “Virtual Standard Switch”. VSS configuration and data is maintained on an individual host level where vDS configuration is saved in the vCenter database and a cached copy is maintained on each host. This cache is updated every 5 minutes. An ESXi 5 host can use both switch technologies at the same time for a “hybrid” implementation.

Check out two great articles over at GeekSilver’s Blog on vDS:

Also have a look at VMware KB Article 1010555 “Overview of vNetwork Distributed Switch Concepts”

Skills and Abilities

Understand the Use of Command Line Tools to Configure Appropriate vDS Settings on an ESXi Host

Will most configuration of a vDS is done via the vCenter Client there are a few commands that can be used from the CLI:

To list and view all switches (vSS and vDS) on a host

# esxcfg-vswitch –l

Add an uplink to a DVPort on a DVSwitch

# esxcfg-vswitch –add-dvp-uplink=<vmnic> (or –P)

Delete an uplink from a  DVPort on a DVSwitch (Must specify DVPort ID)

#esxcfg-vswitch –del-dvp-uplink=<vmnic> (or –Q)

Specify a DVPort Id for the operation

#esxcfg-vswitch –dvp=<dvport> (or –V)

Determine Use Cases For and Apply Port Binding Settings

Port binding determines when and how a virtual machine’s virtual NIC is assigned to a virtual switch port. There are three port binding options that are configurable at the port group level:

  • Static Binding– The default setting, a virtual switch port is permanently assigned to the VM’s NIC when the NIC is configured. No further VM connections are possible once all current virtual switch ports are assigned
  • Dynamic Port Binding (Deprecated in ESXi 5.x)– The virtual switch port is assigned to the VM’s NIC at the moment the virtual machine is powered on. This option allows for virtual switch port over commitment
  • Ephemeral Port Binding (None) – Resembles the behavior of standard virtual switch port assignment, the number of ports will be automatically set to unlimited. You can continue to connect virtual machines up to the maximum number of ports available for a distributed switch

Review VMware KB Article 1022312 “Choosing a port binding  type” for more details

Configure Live Port Moving

From the Blog article “VMware Networking: Configuring and Troubleshooting a vNetwork Part 2” Live Port Moving is described as:

Transfer stand-alone port groups to distributed port groups, assigning settings associated with distributed port group to the stand-alone group

As there is no mention that I could find in the VMware core document set for Live Port Moving that will have to do. Smile

To configure follow the below steps:

  1. In the vSphere Client, display the Networking inventory view and select the dvPort group
  2. From the Inventory menu, select Network –> Edit Settings
  3. Select Advanced to edit the dvPort group properties
  4. Choose whether to allow live port moving
  5. Click OK

Given a Set of Network Requirements, Identify the Appropriate Distributed Switch Technology to Use

Besides offering the vDS, VMware also allows for a 3rd party switch to be installed and used on ESXi hosts (rides over the top of the vDS technology). Currently the only vendor supplied switch on the market is the Cisco Nexus 1000v. Listed below is various information about both:

  • vDS and Cisco 1000v require Enterprise Plus licensing
  • 1KV requires additional licensing from Cisco (per CPU)
  • vDS is managed via vSphere Gui/1KV is managed via Cisco IOS
  • 1KV uses a virtual supervisor module and virtual Ethernet module

VMware and Cisco have put together to papers outlining the use of the Nexus 1KV (still relevant though base on vSphere 4.x)

Configure and Administer vSphere Network I/O Control

Enabling Network I/O Control is a easy a checking a checkbox. The configuration is the far more trickier part. Review the following links for further information and “Best Practices” for NIOC:

Use Command Line Tools to Troubleshoot and Identify Configuration Items from an Existing vDS

Other then commands covered in above you can use the net-dvs command on an ESXi host. The command is located in the /usr/lib/vmware/bin directory. To see the use of the command refer to the link above to GeekSilver’s Blog for “vDS, My Understanding Part 1”

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