The Xbox Live service uses UDP ports 88 and 3074 as well as TCP port 3074 for its IP networking. Some people assume it's necessary to set up port forwarding on the router for these ports to enjoy full Xbox Live connectivity ("NAT Open" status). In many cases, this is untrue as NAT technology typically eliminates the need for manual port forwarding.
If you absolutely need to forward ports for compatibility with your network firewalls, use the three above for Xbox Live.→ More - What Is a Port Number?
→ See also - What Is a DMZ? (alternative to port forwarding)
Xbox 360 Game Console - Photo: Getty Images