WordPress MU

I wonder if anyone can or knows how to apply a second level to blogs that I build with Wordpress MU, I explain better with a diagram

What can I do with wpmu is:
universidad.com
universidad.com/facultad-1
universidad.com/facultad-2

I want to know if you can do this:
universidad.com
universidad.com/facultad-1
universidad.com/facultad-1/carrera-1
universidad.com/facultad-1/carrera-2
universidad.com/facultad-2
universidad.com/facultad-1/carrera-1
universidad.com/facultad-1/carrera-2

Each section is independent blogs

Any help on this .. I'm interested

Note: Use the version of wpmu 2.8.3 with default configuration

You can't create separate blogs within blogs, but you can use categories within a blog.

So you could do:

universidad.com/facultad-1/category/carrera-1
universidad.com/facultad-1/category/carrera-2

You can then create separate pages that pull those categories individually.

You could also do it with a multi-site plugin.

thanks tim.more and andrea_r
I know only this plugin but it is premium
http://premium.wpmudev.org/project/blog-types

Use Andrea and Ron's multisite plugin: http://wpmututorials.com/simple-multi-site-plugin-e-book/. It's pay, but it's cheap and it works.

thanks, I'll try