How do you approach your virtual networking?

I ask silly questions sometimes, but I do it for a reason. As a teacher, I i try to inspire you to think. So I ask questions that may seem a little goofy, but I also try to gently guide you down a new path.

I’ve been using this for a while in my vSphere classes (everything I teach that discusses networking, at least) and thought it was worth sharing. I lead off the discussion with a simple question: do you treat an ESXi host any differently than any other physical server while planning to attach it to the network? Sure, an ESXi host likely has more interfaces to cable, but that’s not all you need to think about. A fundamental shift in thought process should occur when thinking about your vSphere hosts and your network.

If you look at the vSphere network architecture long enough, it’s clear that you’re not just connecting a host to your network. You’re actually connecting more infrastructure to your network. You’re connecting physical switches to virtual switches, not connecting hosts to physical switches. Your vmnic devices aren’t really NICs at all – they’re bridging physical Ethernet to virtual Ethernet. Once that realization is made, everything’s different.

I’ll admit, I didn’t come to this realization all on my own – a friend of mine actually introduced me to the idea. We were discussing something about a class, and he drew on the whiteboard something that could easily be described as a cabinet in the context of a physical data center, and then began to explain that it could just as easily represent an ESX host (this was a couple of years ago). And the epiphany struck.

It’s easy for us systems guys (and gals) to avoid this thought process. We were never programmed that way. But the times, they are a changin’, and we need to remember to change with them.

If you think about your networking like any old host, let me suggest, kindly, that you’re doing it wrong. Start thinking about adding a cabinet to your raised floor, and then you’ll be right on track.

Ramblings on ESXi

As VMware continues the push to a Service-Console-less world with ESXi, there are things that we may want to contemplate with our customers.

Something that came to mind earlier today was logging. ESXi, by default, has a built-in syslog, but it writes logs to a local memory-based file system. That means that when the host goes offline, the logs just go away. There is a method by which one can redirect those messages to a specific Data Store, but let’s face it, centralized logging is all the rage! If nothing else, it provides a remote facility that won’t be modified if someone gets into the ESXi host and cleans entries up after they’re done. To me, that’s some pretty important security. So how does one redirect syslog on an ESXi host, you ask?

It’s as simple as changing a single Advanced Setting via the vSphere client. Take a look at this brief blog entry atVirtualizationAdmin.comby David Davis:

Some other things we want to think about in the transition will ultimately all be COS-related, that being the biggest difference between ESX and ESXi.

Does the customer have agents running in the COS for anything?

  • Backup agents – Perhaps it’s time to revisit backup strategies and methodologies.
  • Hardware management agents – Insight Manager, OpenManage, etc – Many of these functions are being replaced through vendor-specific CIM providers. VMware has available 4 total ISOs for ESXi Installable – one for each of the major vendors (HP, IBM, Dell), and the basic ESXi. The vendor-specific distributions have the appropriate CIM providers cleanly integrated. We should work with our customers in their labs to determine if the CIM providers have the functionality necessary for their specific environments.

Scripts in the COS – customers have developed many scripts to help with management activities in the ESX environment. It is time to begin investigating the transitioning of these scripts to a remote environment. There are a couple of directions that a customer could take in porting their scripts

  • vCLI – the vCLI is a set of tools available from VMware to provide much of the COS toolkit on a remote host. The vCLI is available in 3 forms: a Windows installable package, a Linux installable package, and the vSphere Management Assistant (vMA). The two installable packages can be installed on and run from a Windows or Linux environment. The vMA is a Linux-based Virtual Appliance that can be integrated into a customer’s environment and is designed to provide a prepackaged remote scripting environment for a virtual infrastructure. The vMA provides a number of benefits over the installable vCLI tools such as FastPath Authentication to streamline session authentication functionality without compromising security and simplified deployment as an OVF appliance.
  • PowerShell/PowerCLI – PowerShell is fast becoming a favorite management and scripting toolkit of ESX administrators, partially due to the overwhelming number of Windows administrators that have inherited the responsibility of managing the virtual infrastructure. The PowerCLI toolkit from VMware is a robust set of cmdlets and objects to be used from PowerShell scripts to work with a virtual infrastructure
  • Other SDKs from VMware – VMware provides SDKs for API access from Perl and Java as well, if those languages are more to a customer’s liking

There are still some pieces of functionality that are missing from this stack, admittedly. I’ve spoken with customers about the lack of tools available to manage things like RAID controllers from ESXi. Many of these things are up to the hardware vendors to implement, but VMware can be a conduit for functionality requests as well. We can work with customers to file feature requests through VMware ( When filing such a request, please be as specific as possible regarding what functionality is being requested. Using the above-mentioned RAID controller management as an example, a good feature request may document that a user would like to be able to add disks to a RAID array, create a new RAID array, destroy a RAID array, and rebuild a RAID array after disk replacement. The more specific the requests are, the move VMware can help implement the functionality.

Expanded functionality seems to be the focus of the next release of vSphere (from the small amounts of info flowing out of VMware’s recent Partner Exchange), and the product continues to improve. Just because a customer doesn’t want to migrate now is no reason to put off testing, evaluation, and porting of the customer-developed management tools.

Just remember, I’m a consultant and a trainer, and these are the kinds of things I think about 🙂