Something to be wary of when using a virtualisation server such as ESX, ESXi, HyperV, Xen Server etc.
You may see the errors:
- Access denied to one or more connecting devices on this port, or
- This port is blocked by Spanning Tree Protocol
By default the Cisco Catalyst Express uses smartports and sets each port (except the uplinks) to the desktop role.
One of the features of the desktop smartport is that it doesn’t allow multiple network (MAC) addresses on the same port. This is a problem with Virtualised servers as there can be multiple “virtual” servers using one “physical” network port. You may see the error below.
You may also see errors with STP blocking the port.
Change the smartport role for the affected port to “other”.