I'm about to add a new sub-domain to our site. It will be related to the main site theme but different enough that I want to split it off into subdirectory as a sub-site. I intend to put it into a sub-directory off the main site that bears the name of the sub-topic.

For discussion purposes, let's say the main site them is "widgets" and the sub-site's topic is "broken widgets". So the sub-site will go into a sub-directory off the public root called "broken-widgets", with its own home page and internal linking structure. I will map the sub-domain to this sub-directory.

My concern is that I don't want to split page rank between the two different possible canonicalizations for each page, since they can be referenced either through the sub-domain or via the sub-directory. For example, in the case of the sub-domain public root -> "broken-widgets.widgets.com/" vs "www.widgets.com/broken-widgets"/.

So now the question. I want to create an htaccess file that redirects all page references to one canoncalizated URL form. Which way is the best way to go to get the best possible results with the search engines? Do I force all URL accesses to the sub-directory to the sub-domain? Or do I force all sub-domain accesses to the sub-directory?

Also, if anyone has a good htaccess redirect sample for doing one or the other that would be great.

Cheers.