Projects within projects

I'm currently working on a project made up of parts that could each be considered a project in itself. I plan on using redmine or trac to manage the project. Now I'm trying to figure out how to manage the repo(s) for the project.

These are the current options I have in mind:

1. Create a separate repository for each sub-project and manage each
separately in redmine (separate bug tracker, wiki, etc.)

2. Create a single repository with a subdirectory for each sub-project.

3. Use git submodules or subversion externals to combine options 1 and 2
by creating a separate repo for each sub-project, then creating a master
repo with subdirectory for each sub-project that imports from their
respective repositories.

What's the best way to handle this situation? Are git submodules and/or svn externals sufficiently capable of dealing with this?

Thanks, nic.