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For example, all VoIP calls on a specific port number are routed to the VoIP phone, and all Xbox Live gaming traffic is routed to the Xbox. You might see this sometimes in an IP address: 192.168.0.101:92. In this example, 92 (separated from the rest of the IP address with a colon) is the destination port associated with that IP address. Why bother to have port forwarding, you might ask? Port forwarding basically “fixes” applications that get “broken” by NAT routers. Port forwarding enables Internet traffic to find its way through your NAT so that it can get to the software or hardware endpoint it is looking for.
Firewalls use the same concept of ports, but instead of forwarding, they filter or block specific ports to keep traffic off of your network. Sometimes you need to open or allow ports on your router’s firewall to enable certain applications to function correctly — we talk about this in a bunch of different places throughout the book, whenever the need to open ports arises!
Another related concept is the DMZ or demilitarized zone, which routes all packets bound for a certain port directly to a specific computer without connecting that computer to the rest of the devices on your network. Port forwarding creates a sort of “mini” DMZ for a specific application. Your computer is in a DMZ for that application (like port 80, if you have a Web server), but otherwise a normal part of the rest of your network.
Gaming support: Some routers have specialized port forwarding and firewall settings designed to support certain video games right out of the box, without any need to get too fancy with firewall settings and port configuration.
UPnP support: The easiest of all routers to set up, with regards to games and other port forwarding and firewall issues, are those that use a system called UPnP (Universal Plug’n’Play). The UPnP system is designed for computers, routers, gaming consoles, and related devices, as well as applications such as game software and VoIP software. It allows them all to “talk” to each other without your intervention, determining the right settings and configurations they require to play nicely with each other. If your router supports UPnP, for instance, it can automatically set up port forwarding and configure your firewall. You just sit back and enjoy a nice cold one!
Chapter 3: Wireless LAN Infrastructure
QoS support: A few routers, like D-Link’s DGL-4300 Gaming Router (games.dlink.com), examine the data packets on your network not only for firewall and port forwarding purposes, but also for the type of application. On certain applications (in this case, gaming), the router applies QoS (Quality of Service) prioritization to the packets, making sure that they are sent across the network before any others. No longer will your kid’s homework project download interfere with your ability to blow people away in your favorite FPS (first-person shooter) game! Gotta have priorities in life, no?
In the near future, we expect that you’ll see more and more QoS-enabled routers as broadband service providers try to extend their own network QoS into your home and across your local area network!
Switch ports: Most home routers and gateways include a few wired Ethernet ports for connecting devices that aren’t wirelessly enabled. If you’ve got a separate router and access point, you actually use these wired ports to connect your router to the access point. Look for a router with a wired switch (not hub) with a speed of at least 100 Mbps (100BaseT), and perhaps even Gigabit Ethernet (1000BaseT) speed for the best performance for your old-fashioned wired gear.
We’re talking about physical ports (or jacks) on your router here, not the IP ports we discussed a few bullet points earlier. We didn’t decide to use the same term for software and hardware applications; we just write about it!
Print server: You may have a big honking networked laser printer at your disposal at work, but at home, most of us get by with compact and inexpensive USB inkjet printers. These printers do a great job of printing documents and even photos, but they typically end up connected to only a single computer at a time. With the right router, however, you can utilize a print server that accepts print jobs from any computer on your network; this means they don’t have to be directly wired to the printer to use it. You don’t need to have your print server built in to your router either. For example, Pat has his printer hidden in a little cubby far from the main router/broadband modem/primary access point. In an instance like this, you can buy a wireless print server device that connects to your network and can go anywhere in your house.
^ POE: Some routers are equipped with a system called POE (Power over Ethernet) that can be really handy when building a wireless network. POE lets you connect a remote access point with only a network cable (a CAT-5e or CAT-6 cable, to use the official terminology), and no power cable. (The power travels over the network cable because the device does not require much energy to run.) POE is great when you’re sticking an access point somewhere far from electricity: It’s a heck of a lot easier to run a network cable yourself than it is to wire in an new electrical outlet! All you need on the far end is a POE-enabled access point.