KNOWLEDGE

• Differentiate physical and virtual switch characteristics
  Physical and virtual switches are different in quite some areas:
  • Spanning tree (STP) is not needed (not even implemented) because
    • Virtual switches cannot be interconnected (can be sized larger than most physical switches)
    • Virtual switches do not have to learn MAC addresses as they are known to the system
    • This (and more) can be found here: http://www.vmware.com/
• Create and modify virtual switches and virtual switch policies
  GUI:
  Go to configuration, Networking en adjust the Virtual Switches. You can change setting, create switches and add physical NICs here.
  CLI (some examples provided):
  Create a Virtual Switch:
  

  esxcfg-vswitch –a 

  Create a portgroup for a virtual switch
  

  esxcfg-vswitch  -A ""

  Hard configure network settings:
  

  esxcfg-nics -s 1000 -d full vmnic0

  Set Loadbalancing properties:
  

  vimsh -n -e "hostsvc/net/vswitch_setpolicy --nicteaming-policy loadbalance_srcid "

  Add physical NICs to VSwitch:
  

  esxcfg-vswitch --link <PhysicalNIC> <vSwitch>

  Remove a Physical NIC from a vSwitch
  

  esxcfg-vswitch --unlink <PhysicalNIC> <vSwitch>

   Configure Cisco Discovery Protocol (example: advertise only):
  

  esxcfg-vswitch -B advertise 

• Enable advanced networking capabilities
  Jumbo frames allow ESX Server 3.5 to send larger frames out onto the physical network. The network must support jumbo frames (end-to-end) for jumbo frames to be effective. Jumbo frames up to 9KB (9000 bytes) are supported. Like TSO, jumbo frames are supported in both the guest operating system and in the ESX Server kernel TCP/IP stack.
  
  Before enabling jumbo frames, ensure the NIC or LOM supports jumbo frames.
  Check with your hardware vendor before enabling jumbo frames on your platform. VMware supports jumbo frames with the following vendors: Intel (82546, 82571), Broadcom (5708, 5706, 5709), Netxen (NXB-10GXxR, NXB-10GCX4), and Neterion (Xframe, Xframe II, Xframe E).
  
  To enable jumbo frames in a virtual machine, configure Enhanced VMXNET (supported on a limited number of guests) for the guest. Jumbo frames support is disabled by default in the VMkernel. In ESX Server 3.5, it can be enabled through the Service Console CLI. This configuration option is not available in ESX Server 3i.
  
  iSCSI with jumbo frames is currently not supported.
• TCP Segmentation Offload (TSO)
  TSO is enabled on the VMkernel interface by default, but must be enabled at the virtual machine level. TSO support through the Enhanced vmxnet network adapter is available for virtual machines running the following guest operating systems:
  • Microsoft Windows 2003 Enterprise Edition with Service Pack 2 (32-bit and 64-bit)
  • Red Hat Enterprise Linux 4 (64-bit)

To enable TSO for a VM you must add a new NIC to the VM (possible replacing the exisiting one) if the current NIC is not a Enhanced vmxnet NIC. A new NIC comes with a new MAC address. Optionally you can lookup the existing MAC and use this for the new NIC.

• Jumbo Frames
  To create a vSwitch and Portgroup (for example for vMotion) with Jumbo frames support, first create a vSwitch
  

  esxcfg-vswitch  -A ""

  Use the following command to add a VMkernel NIC to the portgroup with Jumbo Frame support:
  

  esxcfg-vmknic -a -i  -n  -m 9000  

  Use the following to enable jumbo frames on the VMkernel VSwitch
  

  esxcfg-vswitch -m 9000  

• NetQueue
  (info from: http://searchsystemschannel.techtarget.com/)
  NetQueue is disabled by default, and a command line is required to enable it. Once enabled it dramatically improves 10 GbE performance, achieving close to 9.7 Gb of throughput. Without NetQueue, all the I/O requests go to a common queue. When using NetQueue, each VM is assigned to a virtual NIC, and each virtual NIC has its own queue, eliminating the bottleneck. This allows you to subdivide the 10 GbE card on a per-VM basis, delivering near-maximum throughput.
  
  To enable NetQueue, perform the following steps add the line
  

  /vmkernel/netNetqueueEnabled = "TRUE" 

  to /etc/vmware/esx.conf
  At the console, execute the following command:
  

  esxcfg-module -s "intr_type=2 rx_ring_num=8" s2io

  Reboot ESX Server for the changes to take affect.
  To disable NetQueue, perform the following steps remove the line
  

  /vmkernel/netNetqueueEnabled = "TRUE" 

  from /etc/vmware/esx.conf
  At the console, execute the following command:
  

  esxcfg-module -s "" s2io

  Reboot ESX Server for the changes to take effect.
• Identify and understand the impact of various routing protocols
  Ripv2, OSPF, BGP protocols use multicast. If you have a VM that needs the routing protocol information you need to enable multicast on the interface. More information regaring Multicast can be found here: http://www.vmware.com/files/pdf/technology/esx35_ip_multicast.pdf .

SKILLS AND ABILITIES

• Configure service console network using CLI
  To create the Service Console port (first create the vswitch):
  

  esxcfg-vswif -i  -n  -p "Service Console" vswif0

• Configure VLANs (virtual networks)
  To add a portgroup to a vSwitch:
  

  esxcfg-vswitch --add-pg= 

  To define the VLAN to the portgroup (VLAN 0 will disable the VLAN):
  

  esxcfg-vswitch -v  -p  

• Configure TSO and Jumbo Frames
• Enable Cisco Discovery Protocol
• Use CLI commands to modify virtual network configuration

TOOLS

• CLI
  • esxcfg-nics
  • esxcfg-vswitch
  • esxcfg-vmknic
• VI client