A vSwitch on an ESX host is basically software that is contained in the memory of the host servers that connect virtual machines (VMs) with physical NICs. Here are a few scenarios that cover how network traffic is routed in different situations between two VMs on the same host server:

Different vSwitches, same port group and VLAN - VM1 is connected to vSwitch1 and VM2 is connected to vSwitch2. In this example the VMs are plugged into separate vSwitches on the same host server. Network traffic between VM1 and VM2 goes from a physical NIC on vSwitch1 to a physical switch that it is connected to and then back to a physical NIC on vSwitch2 and then to VM2.

Click to enlarge.

Same vSwitch, different port group and VLAN – VM1 is connected to vSwitch1, Port Group A. VM2 is connected to vSwitch1, Port Group B. In this example the VMs are plugged into the same vSwitch on the same host server. Network traffic between VM1 and VM2 goes from a physical NIC on vSwitch1 to a physical switch that it is connected to and then back to a physical NIC on vSwitch1 and then to VM2.

Click to enlarge.

Same vSwitch, same port group and VLAN – VM1 is connected to vSwitch1, Port Group A and VM2 is connected to vSwitch1, Port Group A. In this example the VMs are plugged into the same vSwitch and the same port group on the same host server. Network traffic between VM1 and VM2 never leaves the host server and does not go to the physical NICs on the host server and thus never travels on the physical network.

Because network traffic between VMs on the same host, same vSwitch and same port group does not leave the host it can be advantageous to configure VMs that have a lot of network traffic between them in this manner (for example, a Web server and an application server or an application server and a database server ). Doing this will result in increased network speed and reduced network latency between the VMs. If you use VMware Distributed Resource Scheduler (DRS) you might also consider creating a rule to ensure that the VMs stay on the same host.

Click to enlarge.

What is the “Best of VMworld” competition?

The Best of VMworld is a product competition put on at VMworld each year. In this competition, IT pros serve as judges to select the best products in seven categories. This year, there were 13 judges who came from a variety of backgrounds, spread across the different categories. You can read more about the categories and results at the Best of VMworld 2008 webpage. Additionally, you can see a video of the Best of VMworld awards ceremony.

What is the New Technologies category?

I requested to be a judge for the new technologies category because I wanted to have a chance to see what new products were on the horizon. The New Technologies category is made up of products that are not currently out but are coming out in the next few months. The most challenging thing about the new technologies category was that any type of hardware or software could be entered. That meant that we were comparing network software against disk hardware, for example. Because of this and because there were over 30 products entered in the new technologies category, I found this category very challenging to judge.

How did the judging process work?

As this was my first year serving as a judge, I found the whole process very interesting. I worked with my fellow judge, Mike Laverick (www.rtfm-ed.co.uk), to evaluate the 30+ entries in the new technologies category. We had to compare so many different technologies that didn’t match up “apples to apples”. Once we got to VMworld in Las Vegas, we spent a full eight-hour day visiting the companies that had entered to learn about their products. Some companies had new hardware, new software, or updated software products. We looked for a number of things from these companies when we went to learn about their product:

• What does the new technology do?
• How do you install it?
• How do you use its main feature?
• Is the product truly new or is it just an existing product that had a virtualization twist added?
• What benefits will the new technology offer IT Pros?
• How dramatically will this new technology affect virtualization admins?

After getting the answers to these questions, we were able to narrow our list down to just a handful of new technologies. From there, we chose just two:

• Cisco Nexus 1000v
• Vizioncore vOptimizer Pro

Why did I choose Cisco and Vizioncore as the best new technologies of VMworld 2008?

I think that, once you learn about these products, you will understand why we chose these products as the best new technologies, related to VMware. First, let me cover the Cisco Nexus 1000v. Here is what this switch does and what makes it unique:

• It is a software switch that integrates / installs with VMware ESX Server.
• It uses the new distributed virtual switch (dvswitch) feature of the next version of ESX Server
• It recognizes all physical Ethernet ports on all ESX host systems and allows you to manage them as a single switch
• It has a Cisco IOS interface, just like hardware switches do
• Now, with the Cisco virtual switch, network administrators can administer the virtual network, just as they do the physical network.

In my opinion, not only will the virtual switch provide technical benefits, it will provide more ideal delegation of network and virtual server management. In other words, with this new virtual switch, network administrators can manage the virtual network and virtual server administrators can manage the virtual servers. By doing this, many of the finger pointing issues related to virtualization can be eliminated.

The Cisco Nexus 1000v is expected to be available at the same time that the next VMware ESX Server / Virtual Infrastructure Suite is released. (Q1 2009)

Next, let’s cover the Vizioncore’s new vOptimizer Pro. Here is what vOptimizer Pro does and what makes it unique:

• It analyzes all VMware virtual disks and the operating systems inside those virtual disks, determining the amount of free space available.
• Based on settings that you configure, it can resize both the VMDK (virtual disk) and the operating system disk inside to reduce or enlarge their size.
• You can assign a dollar value to the per GB cost of your SAN disk space and, based on the amount of disk space that vOptimizer Pro is able to save you, reports will be generated showing the cost savings of using vOptimizer
• This optimization process can be scheduled to run each day, week, or month and, at that time, the virtual disks will either be increased or decreased as the amount of utilization inside the guest OS is either increased or decreased.

As most virtual disks and operating system partitions inside virtual disks are oversized when created, there is a huge potential for storage savings when the first optimization is run. In fact, what made vOptimizer such a valuable tool, and worthy of being called the “best new technology” of VMworld, was that it performed a task that was easy to understand, it could concretely tell you how much money it saved you, and that it had the potential to pay for itself after the first time it was run.

Vizioncore’s vOptimizer Pro is expected to be released during Q4 2008.

Conclusion

The judging of the VMworld best new technologies was exciting and educational. There are so many new products coming out related to virtualization and all the different types of virtualization continue to evolve. From this article, I hope that you understand the thorough process that we go through, as VMworld best products judges to choose only the best products for TechTarget and SearchServerVirtualization.com. Also, from this article, it should be evident why the Cisco Nexus 1000v and Vizioncore’s vOptimizer Pro were selected – because they both change the way we use virtualization and both are revolutionary, in their own way.

I want to thank my fellow judge, Mike Laverick of www.rtfm-ed.co.uk for his expertise and for working with me to judge this competition.

David Davis (CCIE #9369, VCP, CWNA, MCSE, CISSP, Linux+, CEH) has been in the IT industry for 15 years. Currently, he manages a group of systems/network administrators for a privately owned retail company and authors IT-related material in his spare time. He has written hundreds of articles, eight practice tests, and six video courses -including the Train Signal VMware ESX Video training series. His personal website is www.VMwareVideos.com

In describing how to use the esxcfg-vswitch command, I want to first explain some practice points that I use in my VI3 environment. Most importantly, I create a virtual switch exclusively for the service console and VMkernel (VMotion) roles, and a separate virtual switch for all of the guest virtual machine port groups. The port groups on this separate virtual switch will have 802.1Q VLAN tags applied. With that, let’s jump into the command.

One of the first things you can do is inspect the current virtual switch configuration. This is done with the following command:

esxcfg-vswitch -l

The result will be something similar to what is shown below:

To recreate networks, we can use the esxcfg-vswitch to do this task. My preference is to remove the existing virtual switch, and re-create it to expected configuration. Here is a sample script that will first remove and then re-create the entire virtual switch and five port groups with their corresponding VLAN identifiers:

esxcfg-vswitch -d MainGuestVirtualSwitch
esxcfg-vswitch -a MainGuestVirtualSwitch
esxcfg-vswitch --link=vmnic3 MainGuestVirtualSwitch
esxcfg-vswitch --link=vmnic4 MainGuestVirtualSwitch

esxcfg-vswitch --add-pg=PrivateNetwork MainGuestVirtualSwitch
esxcfg-vswitch --add-pg=ShopFloor MainGuestVirtualSwitch
esxcfg-vswitch --add-pg=BackBuildingUpper MainGuestVirtualSwitch
esxcfg-vswitch --add-pg=BackBuildingLower MainGuestVirtualSwitch
esxcfg-vswitch --add-pg=CoreCorporate MainGuestVirtualSwitch
esxcfg-vswitch --vlan=334 --pg=PrivateNetwork MainGuestVirtualSwitch
esxcfg-vswitch --vlan=332 --pg=ShopFloor MainGuestVirtualSwitch
esxcfg-vswitch --vlan=236 --pg=BackBuildingUpper MainGuestVirtualSwitch
esxcfg-vswitch --vlan=237 --pg=BackBuildingLower MainGuestVirtualSwitch
esxcfg-vswitch --vlan=100 --pg=CoreCorporate MainGuestVirtualSwitch

A couple of notes on this: MainGuestVirtualSwitch is the name for the virtual switch instead off the default vSwitch1 (remember the first one – vSwitch0 – is for service console and VMkernel). There are two interfaces available to this virtual switch, vmnic3 and vmnic4. The port group names are the friendly names of the networks that are used in VI3. After running this script, the following will immediately appear in the networking configuration section of the host in the VMware Infrastructure Client:

I usually go into the virtual switch after it is created through script to make both interfaces active, instead of the default scripted result of one as active and subsequent vmnic interfaces as standby. Good information on esxcfg-vswitch is a little light, but VMworld 2006 had a couple of mentions of it and virtualization expert Mike Laverick makes some mentions of esxcfg-vswitch on the RTFM site.

Like many administrators, I do not backup the ESX host in a traditional sense. Using these configuration scripts in a post-installation fashion can make host re-provisioning quick and painless, but more importantly get the configuration consistent.

I have used the 1.0x version of VMware Server for years in testing and development systems. With version 2.0, I have started to use remote datastores for storing test systems. Datastores are storage locales in VMware Server 2.0. You can add NFS datastores for Linux-based installations of VMware Server. The Microsoft networking server message block (SMB) is available for Windows versions.

From a performance and configuration perspective, a non-local datastore is not ideal for live production systems. For situations like mine where a large number of infrequently used virtual machines are used from VMware server, a remote slower-speed disk suits the need very well. This storage configuration may also be good for archival of certain virtual machines, such as a project build that has gone into support mode.

In my example, I used a network attached storage (NAS) device, which can provide some of the cheapest storage available. NAS default configurations usually provide Windows file and print as a native file-serving option. Adding datastores from the “add datastore” command in the web interface after the initial installation is straightforward:

Once this is done, a virtual machine can be added to the local inventory. When virtual machines run from a remote datastore, the disk I/O is executed on the remote system. Adding a remote datastore also puts the CPU, network and memory functions on the host locally. There is definitely a performance hit from this configuration. But for archival purposes, you can free up more capable storage for your most frequently used virtual machines.

Administrators should also note that the virtual machines must be updated before being visible in 2.0 from a remote datastore before you make a remote datastore for all of your existing servers running VMware Server 1.0x from your VMware Server 2.0 beta system. Once updated to virtual machine version 6.0, the 1.0x systems cannot use the guest virtual machines without being upgraded to VMware Server 2.0.

The following section illustrates how to add a virtual machine to the inventory after upgrading:

This can save time by possibly eliminating the need to copy large virtual machine files back and forth over your network.

Most of us are not network admins as well as virtualization admins, so we have to start with some good resources to “get what we want.” Without VLAN trunking, each VLAN you would want to connect to would require its own physical interface. That clearly is a growth and agility inhibitor as well as incredibly expensive for additional cable runs and interfaces on your ESX servers. Quoting Andrew Kutz, “that makes ESX practically worthless.” So I am on a mission to turn the tide. There is a good resource online from VMworld 2006 that explains the ESX networking so that we can inform ourselves, and better integrate with our network staff to ensure all standards are met.

With networking, configuration consistency among ESX servers becomes absolutely critical (as is with other areas of VI3). It is important to deliver the ESX configuration as planned, as if there is a variation and an outage or other networking issue, there may be a swift change of heart from your networking staff.

Readers, I invite you to share your experiences with making the case for trunking below with a comment.

To configure a virtual machine to not have its network connected at power-on, edit the settings of a virtual machine and deselect the option as shown in the figure below:

Once you are done with your staging configuration, power off the virtual machine and change the option back to connecting at power on.

Extra Step in Protection

With VMware ESX, it is simply too easy to accidentally cause conflicts that may arise from having a candidate virtual machine on the network too early and performing its intended tasks. Errors can be a duplicate IP address, the application on the virtual machine picking up data simultaneously as the live system, formatting issues from a newer version of a business system feeding results to another system, and many other situations.