Category Archives: ESXi

Beacon Probing Deep Dive

Today I’ll be looking at a feature I’ve wanted to examine for some time – Beacon Probing. I hope to take a fresh look at this often misunderstood feature, explore the pros, cons, quirks and take a bit of a technical deep-dive into its inner workings.

According to the vSphere Networking Guide, we see that Beacon Probing is one of two available NIC failure detection mechanisms. Whenever we’re dealing with a team of two or more NICs, ESXi must be able to tell when a network link is no longer functional so that it can fail-over all VMs or kernel ports to the remaining NICs in the team.

Beacon Probing

Beacon probing takes network failure detection to the next level. As you’ve probably already guessed, it does not rely on NIC link-state to detect a failure. Let’s have a look at the definition of Beacon Probing in the vSphere 6.0 Network guide on page 92:

“[Beacon Probing] sends out and listens for beacon probes on all NICs in the team and uses this information, in addition to link status, to determine link failure.”

This statement sums up the feature very succinctly, but obviously there is a lot more going on behind the scenes. How do these beacons work? How often are they sent out? Are they broadcast or unicast frames? What do they look like? How do they work when multiple VLANs are trunked across a single link? What are the potential problems when using beacon probing?

Today, we’re going to answer these questions and hopefully give you a much better look at how beacon probing actually works.

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Suppressing ESXi Shell and SSH Warnings

Are you tired of seeing SSH and Shell warnings on your ESXi hosts? If you are at all like me, it’s maddening to see yellow warnings and banners on hosts in the vCenter Server inventory – especially when it’s for something as simple as the ESXi Shell and SSH service being enabled.

Granted, what’s a minor annoyance in a lab environment might be a warning that’s taken seriously in a locked down production environment. In these sorts of environments, administrators will need to enable/disable SSH and Shell access on an as-needed basis. Without the alarms and banners, services may be left turned on accidentally.

 

ESXi Shell and SSH warning banners

Nobody likes warning banners on the summary page 😦

If you are using vSphere 6.0 or later, there is a nifty new ‘Suppress Warning’ option in the vSphere Web client. It can be found on the summary page of an ESXi host with an ESXi Shell or SSH warning currently triggered.

As you can see in the above screenshot, there are separate alerts for both the ESXi Shell and for SSH as well as an option to ‘Suppress Warning’ on each. Although it may appear that each can be suppressed independently, clicking one of the ‘Suppress Warning’ links will disable both ESXi Shell and SSH warnings on the host.

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