Residential Gateways Bring Range of Options into Home
Bruce Brown
If you’re setting up a new home network or expanding an existing network, you should probably consider buying and using a residential gateway, especially if multiple PCs share a single broadband Internet link (such as cable or DSL) via your network. The most basic residential gateways act as routers and have internal software that manages Internet sharing and adds vital security features to protect your PCs from threats from other people or PCs on the Internet.
Residential gateways have evolved to encompass more useful home networking features and functions–during 2001 you can expect existing vendors and new players to continue to add features and value in this product category.
While the two basic functions performed by residential gateways are Internet access sharing and protection, alternatively you can use software to manage Internet access sharing, such as the Internet Connection Sharing (ICS) feature of Windows 98SE and Windows Me. But there are two downsides of ICS: one computer has to be assigned to act as an Internet access server (which means all PCs on your network aren’t equal) and that PC must be turned on and running correctly in order for the other networked PCs to get to the Internet. If you use a residential gateway, not only is setup easier than using ICS, but you can turn off your other PCs and just leave your modem and the gateway turned on, and you can selectively power up any PC to access the Internet.
Residential gateways (which typically come with one RJ-45 jack to plug into a cable or DSL modem) let you share Internet access by internally managing TCP/IP addresses. Some newer gateways may have the DSL modems included, like the 2Wire HomePortal 1500 series. Most of the devices now on the market can be configured via an Internet browser on a PC located on the same network. The gateway sets up a subnetwork using TCP/IP addresses not viewable from the Internet (see our story “The Darkside”). All that’s presented to the Internet and your ISP is the single IP address of your DSL or cable modem.
Dynamic Host Configuration Protocol (DHCP) and Network Address Translation (NAT) are used to assign IP addresses to systems on your network and help protect your network from intruders. Both features are included in residential gateways. Just to back up a bit, in situations without residential gateways installed, you can have individual IP addresses manually assigned to each of your networked systems, assuming you purchased multiple real IP addresses from your ISP at an extra cost. More often you’ll use DHCP to receive automatically assigned IP addresses from your ISP for each session if your Internet connection is via standard modem or ISDN. Some ISPs issue fixed IP addresses for DSL and cable modem, others use DHCP.
A residential gateway can be configured to use DHCP when communicating with your ISP to derive a single IP address to be shared by systems on your network. The gateway can then dynamically use DHCP protocols and NAT within your internal network to assign IP addresses to your PCs, which need to be configured to use DHCP to obtain IP addresses automatically (see “Home Networking Tutorials”).
NAT sets up a table that keeps track of your network’s internal IP addresses (for devices on your network that can access the Internet) and translates internal IP addresses to the actual IP address assigned by your ISP. NAT effectively shields the internal IP addresses from the Internet providing a minimal form of firewall protection.
Here’s how DCHP actually works in a gateway: the subnetwork (your home network) managed by the residential gateway, often gets assigned the IP address 192.168.0.1, and any PC that boots while plugged into the gateway (typically via a hub or switch, although some gateways include in integrated 4-port or 7-port 10/100 Ethernet switch) automatically gets assigned an address on the subnet. With the gateway powered on, for example, the first PC to power up would be automatically assigned the IP address 192.168.0.2.
As subsequent PCs or other devices that support the TCP/IP protocol are powered on (print servers, MACs, or NIC-equipped PDAs, for example), each is assigned another address in the subnet range, which typically can be used for up to 253 addresses. Note that if you turn a PC off, it’s internal IP address is immediately available to the next PC that powers on. Generally this doesn’t matter unless you’re using a program that requires that you enter a fixed IP address (even if the address is an internal address).
Whether you are using fixed or Dynamic IP addresses, you can check the IP address currently assigned to your Windows PC by clicking Start, Run, and typing “winipcfg” under Windows 98/98SE/ME in the program box, or bring up a CMD prompt ((type CMD at the Start/Run dialog box)) under Windows NT/2000/XP and type “ipconfig/all” at the command line. A window will open similar to the one below.
Click on the top window to find your NIC and you’ll see your current IP address on the third line (192.168.0.3 in the current example).
There are a host of additional security features in software in residential gateways, including features that enable accessing Virtual Private Networks (VPNs) and for playing Internet-based games. Other features include filtering incoming and outgoing content and support for additional network and security protocols.
Setup is getting easier with residential gateways–compared to configuring a traditional router, for example. Usually all you have to know ahead of time is the type of broadband Internet access you have, the carrier name, whether or not a fixed IP address is assigned to your account (and if so what it is), and, again if required, your user name and password.
In addition to the standard router, Internet sharing, and firewall features, residential gateways are available with a growing menu of additional features. The first common addition was a 4-to-7 port Ethernet hub or switch–saving the expense of buying a separate box. Gateways are now available that include internal bridges so you can use the single device with more than one network type–for example supporting Ethernet and HomePNA, Ethernet and 802.11b wireless, or HomeRF wireless networking with the same box. There are also some that go further, bridging multiple networks with support for all of the above plus direct connect USB networked PCs. When powerline network devices come on the market later this year, those devices will also likely be supported on residential gateways.
A few residential gateways available today add a parallel printer port and come with software you can install on your network PCs that create an addressable port that the PCs treat as a local port but actually refer to the port on the gateway. Later in the year residential gateways with internal hard drives for network storage will be available–these devices will likely run on Linux or other non-Windows operating systems and act as network servers, but in a manner that is transparent to users.
Today home networks aren’t used often for voice transmission, but the manufacturers are promising that voice will be one of the “next big thing” with Internet applications and for home networks. As streaming media technology and networks to support it develop further, that too will show up on residential gateway feature lists.
Even if you only use a few PCs to access the Internet via a cable or DSL modem, it’s a good idea to buy a residential gateway, with basic models that include multiple Ethernet ports selling for $150 or less.
Copyright © 2004 Ziff Davis Media Inc. All Rights Reserved. Originally appearing in ExtremeTech.
