Just off the top of my head I can remember 2 categories. Depends on whether you're talking about connections such as frame relay, atm, etc... Or level 2 switching, level 3 switching, etc... In the second case, switching can occur all the way up to the application layer. I'd recommend hitting Cisco's main site under the products link and check out everything from the small office home office (SOHO) to the enterprise class equipment. Data sheets would be a great source of info. And if you want to go deeper, the configuration guides could provide you with plenty of reading.