Tuesday, June 2, 2009


• ESX Server Networking
• Virtual Switches
• Virtual Switches and VLANS

How virtual machines communicate with rest of the appliance in network.

Why we need virtual networking
==> Each device requires a NIC, this NIC allow a device to communicate with rest of the devices in the network. With the introduction of virtualization in Vmware we have one big host which is physical device and several machines running on that physical host . And in a traditional sense you would need a NIC card for every virtual machine to allow connectivity to rest of the network , and it does not make sense to make 20-30 nic cards for virtual machines and this is where the concept of virtual switch comes into play.

A virtual switch mimics a physical switch except it is a software based and it will have ports in it and these ports can be added or deleted. You can have upto 1016 ports on a virtual switch.

The idea here is to connect one or more physical nic cards to this virtual switch, the virtual switch is server by one or more physical nic cards.

So we connect the VM machines nic with the virtual switch ports and virtual switch gives the connectivity to the outside world via physical NIC.

In the above scenario both vm are connected with the virtual switch and VS is not connected with any physical NIC. So they can talk to each other only and this is perfect for testing only.

Next Scenario

One virtual switch with one physical nic.
As we gave physical connectivity so you can do traffic shaping.

Another scenario

Advantage is redundancy as you have multiple nic card.

One more scenario


There are 3 types of port configuration that can we done on a virtual switch
• Service console
• Vmkernel : vmotion,iscsi, nfs/nas
• Virtual machines

On the same virtual switch you can have one or more port types ,
You can have virtual switch that supports port for the service console and also for vm for example or each virtual switch can have its own port types so all the ports on this virtual switch will only support virtual machines or service console or vmkernel.

Rolling Failover
No:= in the event that a physical nic card goes down and another nic card takes over its place continues production, after the failed nic card comes back online if this setting is sets to NO then the failed nic card that just came online will tackle the existing nic card will take its place and return to the servicing production.
If it is set to
YES: then the failed nic card remains offline even after it recovers from the failure that it experience and it will not take over the currently active nic card until the event another failure happens.

Network Failover Detection:-
Link state only--> if the failure is from switch end then the esx server will not able to know that
Becon Probing--> it will notify the esx that link from switch is down

• Service network restart ---when you want to change the ip address of service console
• Ifconfig --
• Findnic -- able to map the way esx server labels the vm nic to the actual physical nic.
• Mii-tool -- used to configure or modify nic settings from command line stand point from vm

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