Category: networks

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Automatic Segmentation of VDI Endpoints

Automatic VLAN assignment and use of DHCP relays

Software defined datacenters (SDDC) enable us to keep many components within the hypervisors software layer. But sooner or later we need to exit that layer in order to get in touch with the user. Usually Thin- or Zeroclients are used as VDI endpoints. Those hardware boxes are connected by LAN and need to have an IP address.

I will demonstrate how to assign endpoints  to separate them into subnet segments and VLANs and still assign IP addresses by a centralized DHCP server.

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ESX physical uplink resiliency (part 2)

What is beacon probing?

In my recent blog article “ESX physical uplink resiliency” I’ve discussed countermeasures to harden vSphere traffic against downstream physical failures. Today I will discuss another failover detection method which can handle uplinks that are not yet dead but not functional either.

Reasons for failure can be driver / firmware related errors on the NIC itself, or a broken downstream path (cable / switch).

Beacon probing

Beacon probing is a mechanism, where an ESX host will send out beacon packets over every uplink port every second to verify that each other uplink is reachable.

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Problem with Emulex OneConnect OCe14000 NIC LoM

Troubleshooting driver, firmware and ESXi version combinations

Hardware failures in vSphere clusters normally aren’t a big issue. Almost every component is redundant in one or the other way. If one component fails, another one will jump in and take over its function. Malfunction is a different thing and more serious than failure. Such a Zombie can become a real problem because as long as there are signs of life, a replacement will not jump in and there will be no failover.

I witnessed such a situation after a scheduled reboot of a Top-of-Rack (ToR) switch. An ESXi host that was connected to the switch with a 10 Gbit uplink became malfunctioning but didn’t fail.

As you can see in the picture, the link indicator and activity LEDs are active although the cable has been disconnected. A true sign that there is something wrong.

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