Rodrigo,
I recommend you post this question to the Cisco Support Community where Cisco technical support experts provide assistance. You will be able to find information regarding a 3COM switched environment.
https://supportforums.cisco.com/index.jspa
We do encourage you to participate in the Cisco Collaboration Community and to also join our Cisco Collaboration User Group program! In the community, we encourage your discussion/sharing around collaboration topics and Cisco Collaboration Solutions, including business and IT requirements, industry trends, process, culture/organization issues, how collaboration can be used to transform businesses, vendor selection, adoption, training, architecture, licensing, and product features/functionality. If you are a customer or partner, you can also join the user group program to be eligible for member-only events and influence product direction.
We hope to hear from you again.
Kelli Glass
Moderator for the Cisco Collaboration Community