October 26 2009
Vsphere VCP-410 Lab 5 part 1
Exam Objective: Create/Delete Virtual Switches
Contents
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• Introduction
• Technology Background
• Lab Scenario
• Lab Objectives
• Lab Solution
Introduction
A virtual switch, or vSwitch, works much like a physical Ethernet switch. It detects which virtual machines are
logically connected to each of its virtual ports and uses that information to forward traffic to the correct virtual
machines. A vSwitch can be connected to physical switches by using physical Ethernet adapters, also referred to
as uplink adapters, to join virtual networks with physical networks. This type of connection is similar to
connecting physical switches together to create a larger network. Even though a vSwitch works much like a
physical switch, it does not have some of the advanced functionality of a physical switch.
You can create abstracted network devices called vNetwork Standard Switches (vSwitches). A vSwitch can
route traffic internally between virtual machines and link to external networks. You can use vSwitches to
combine the bandwidth of multiple network adapters and balance communications traffic among them. You can
also configure a vSwitch to handle physical NIC failover. A vSwitch models a physical Ethernet switch. The
default number of logical ports for a vSwitch is 56, but it can have up to 1016 ports in ESX. You can connect
one network adapter of a virtual machine to each port. Each uplink adapter associated with a vSwitch uses one
port. Each logical port on the vSwitch is a member of a single port group. Each vSwitch can also have one or
more port groups assigned to it. You can create a maximum of 127 vSwitches on a single host.
When two or more virtual machines are connected to the same vSwitch, network traffic between them is routed
locally. If an uplink adapter is attached to the vSwitch, each virtual machine can access the external network
that the adapter is connected to.
Technology Background
How Virtual Switches Work
Virtual switches are the key networking components in VMware Vsphere4. You can create up to 248 virtual
switches on each ESX Server 4.0 host. A virtual switch is “built to order” at run time from a collection of small
functional units. Some of the key functional units are:
• The core Layer 2forwarding engine. This is a key part of the system (for both performance and
correctness), and in Virtual Sphere 4it is simplified so it only processes Layer 2Ethernet headers. It is
completely independent of other implementation details, such as differences in physical Ethernet
adapters and emulation differences in virtual Ethernet adapters.
• VLAN tagging, stripping, and filtering units.
• Layer 2security, checksum, and segmentation offload units.
This modular approach has become a basic principle to be followed in future development, as well. When the
virtual switch is built at run time, ESX Server 4 loads only those components it needs. It installs and runs only
what is actually needed to support the specific physical and virtual Ethernet adapter types used in the
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configuration. This means the system pays the lowest possible cost in complexity and demands on system
performance.
The design of ESX Server 4 supports temporarily loading certain components in the field — a capability that
could be used, for example, for running appropriately designed diagnostic utilities.
An additional benefit of the modular design is that VMware and third-party developers can easily incorporate
modules to enhance the system in the future.
In many ways, the ESX Server virtual switches are similar to physical switches. In some notable ways, they are
different. Understanding these similarities and differences will help you plan the configuration of your virtual
network and its connections to your physical network.
