https://support.activision.com/articles/en_US/FAQ/Lag-Occurs-in-Multiplayer-GameMany broadband internet modems now come with routing capabilities built in. Please contact your internet service provider to determine if your internet modem has an integrated router. If it does, they should be able to assist you with the steps for setting up your home network.Once you have completed the steps above, the game should report your NAT type as Open and should make use of the maximum bandwidth supported by your internet service provider for your account.To see what NAT type is detected by the game:- Go to the Multiplayer menu.- Select Options.- Select System Info.In the System Info panel, there will be a category called NAT Type. If the game reports your NAT type as Strict, you will have difficulties playing online and will need to adjust your router settings or replace it with a gaming console compatible router. If the game reports your NAT type as Moderate, you may have difficulties connecting to some game hosts. An Open NAT type is the best setting for online gaming. Find out more about Port Forwarding and NAT Types.
http://support.activision.com/articles/en_US/FAQ/Port-Forward-and-NAT-FAQWhat are ports, and what is port forwarding?Ports are simply virtual pipelines that allow computers and devices to communicate and send information back and forth on the Internet. See more about ports used for Call of Duty games.Port forwarding – or creating a port forward – is a common process in gaming that makes your gaming console or PC more accessible to other gaming consoles or PCs on the Internet. Port forwarding can improve connection speed, lobby wait times, and overall gameplay, particularly for a host.What about NAT?NAT (Network Address Translation) is a networking concept that allows your router to share a single IP (Internet Protocol) address across multiple devices on your network. Instead of your ISP (Internet Service Provider) assigning an IP address to every device that connects to the Internet, NAT allows your ISP to assign a single IP address to your router. The router then manages a set of IP addresses for all devices on your home network.There are three main NAT types depending on your platform: Open, Moderate, and Strict on Microsoft or PC, and Type 1, Type 2, and Type 3 on Sony. Moderate/Type 2 and Strict/Type 3 NAT types limit the connections your gaming console or PC can make to other gaming consoles or PCs. For example, Moderate/Type 2 NATs can only connect with gaming consoles or PCs using Moderate/Type 2 or Open/Type 1 NAT, and Strict/Type 3 NATs can only connect with gaming consoles or PCs using Open/Type 1 NAT. Ultimately, an Open/Type 1 NAT will provide the best connection quality.