On the Mac Pro:

Here’s how you can set this up on your own Mac with two built-in ethernet ports :

1. Open System Preferences

2. Go to System Preferences -> Network

3. Select the small cog in the bottom left side (next to the + and –) and choose Manage Virtual Interfaces…

4. Select the + in the bottom left and choose New Link Aggregate…

5. Then you select the two Ethernet interfaces and name the new interface whatever you want. Once finished, click the Create button.

6. After that it will appear in the network list as one network interface with a bond ID.

7. Click Apply to activate the new virtual Ethernet service.

Apple also has a KBase article available on this subject: http://support.apple.com/kb/PH8356

On R7000:
http://www.dd-wrt.com/phpBB2/viewtopic.php?p=939340