October 26 2009
Vsphere VCP-410 Lab 6 part 1
Exam Objective: Create Ports/Port Groups
Contents
• Introduction
• Technology Background
• Lab Scenario
• Lab Objectives
• Lab Solution
Introduction
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The ports on a virtual switch provide logical connection points among virtual devices and between virtual and
physical devices. You can think of them as virtual RJ-45 connectors. Each virtual switch can have up to 1,016
virtual ports, with a limit of 4,096 ports on all virtual switches on a host.
The virtual ports in ESX Server provide a rich control channel for communication with the virtual Ethernet
adapters attached to them. ESX Server virtual ports:
• Know authoritatively what the configured receive filters are for virtual Ethernet adapters attached to
them. This means no MAC learning is required to populate forwarding tables.
• Unlike physical switches, know authoritatively the “hard” configuration of the virtual Ethernet adapters
attached to them. This capability makes it possible to set such policies as “guest can’t change MAC
address,” because the virtual switch port can essentially know for sure what is “burned into ROM”
(actually, stored in the configuration file, outside control of the guest operating system).
Technology Background
Port groups aggregate multiple ports under a common configuration and provide a stable anchor point for
virtual machines connecting to labeled networks. You can create a maximum of 512 port groups on a single
host.
Each port group is identified by a network label, which is unique to the current host. Network labels are used to
make virtual machine configuration portable across hosts. All port groups in a datacenter that are physically
connected to the same network (in the sense that each can receive broadcasts from the others) are given the
same label. Conversely, if two port groups cannot receive broadcasts from each other, they have distinct labels.
A VLAN ID, which restricts port group traffic to a logical Ethernet segment within the physical network, is
optional. For a port group to reach port groups located on other VLANs, the VLAN ID must be set to 4095. If
you use VLAN IDs, you must change the port group labels and VLAN IDs together so that the labels properly
represent connectivity.
Port groups are important particularly for VMotion. To understand why, consider what happens as virtual
machines migrate to new hosts using VMotion. Port groups make it possible to specify that a given virtual
machine should have a particular type of connectivity on every host on which it might run. Port groups are usernamed
objects that contain enough configuration information to provide persistent and consistent network
access for virtual Ethernet adapters:
• Virtual switch name
• VLAN IDs and policies for tagging and filtering
• Teaming policy
• Layer 2security options
• Traffic shaping parameters
In short, port group definitions capture all the settings for a switch port. Then, when you want to connect a
virtual machine to a particular kind of port, you simply specify the name of a port group with an appropriate
definition. Port groups may specify different host-level parameters on different hosts — teaming
configurations, for example. But the key element is that the result is a consistent view of the network for a
virtual machine connected to that port group, whichever host is running it.
Port Group Configuration for Virtual Machines
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You can add or modify a virtual machine port group from the vSphere Client. The vSphere Client Add Network
wizard guides you through the tasks to create a virtual network to which virtual machines can connect,
including creating a vSwitch and configuring settings for a network label. When you set up virtual machine
networks, consider whether you want to migrate the virtual machines in the network between hosts. If so, be
sure that both hosts are in the same broadcast domain—that is, the same Layer 2 subnet.
ESX does not support virtual machine migration between hosts in different broadcast domains because the
migrated virtual machine might require systems and resources that it would no longer have access to in the new
network. Even if your network configuration is set up as a high-availability environment or includes intelligent
switches that can resolve the virtual machine’s needs across different networks, you might experience lag times
as the Address Resolution Protocol (ARP) table updates and resumes network traffic for the virtual machines.
Virtual machines reach physical networks through uplink adapters. A vSwitch can transfer data to external
networks only when one or more network adapters are attached to it. When two or more adapters are attached to
a single vSwitch, they are transparently teamed.
