Q: migration assistant el capitan

I am trying to use migration assistant from my 2010 MacPro to new iMac (late 2015).

Originally on same network, the MacPro was not being recognized.

I tried connecting via Ethernet (both Cat 6 and ethernet cables) including rebooting both computer--still no recognition.

Checked sharing -- seems to be set and with a name.

My MacPro was using 10.8.5, but the info page said only 10.6.8 was needed, but just in case I'm upgrading to El Capitan.

Questions:

1. Assuming ethernet connection will speed transfer--which cables are correct? (once upon a time I had twisted ethernet cables, but no more).

2. How do I get them to recognize each other?

Many thanks.