The term gateway was the original name for a router. The term is still sometimes used as a synonym, but most often the term implies routing between two or more totally distinct and independent networks environments. Wireless gateways match this definition; they serve as a gateway into another network. They are typically multifunction devices. Wireless residential gateways connect a small number of wireless devices to the Internet or to another network. Wireless Enterprise gateways connect multiple access points and the associated clients to the main wired network of the Enterprise. They have many additional features, as well.
Wireless residential gateways provide the small office and home office (SOHO) users with an affordable all-in-one device that is easy to configure and able to handle most network needs.. In addition to the gateway itself (router), common built-in functions include the following:
- Router – The router is the gateway. Options include DHCP server, NAT server, and Internet firewall for your existing network. The TCP/IP protocols are supported.
- Wireless access point – Common options include 802.11a, 802.11b, 802.11g, or some combination of these, for dual/triple-mode APs. The distinctive look of the 802.11 diversity antennas tends to make many residential gateway look like an AP.
- Wired access – Includes a 4-or-more-Port switch, with Ethernet
- WAN port – This is the Internet interface to the Ethernet port that is connected to the service provider equipment, such as a cable or DSL modem or a dial-up modem. Although two-way satellite service is also becoming popular as a SOHO broadband connection, the most widely used of the satellite providers, Hughes Network Systems (HNS), offers only a high-priced gateway more suitable for a corporate than a SOHO environment. There are no third-party gateways currently available for the USB connector of the HNS satellite modems.
- Print server – Some gateways include a standard parallel printer port, so that a connected printer is available to all users on the local wired and wireless LANs.
- VPN – When security is important, built-in Virtual Private Network (VPN) functionality will simplify the administrator’s tasks.
Networking with a Wireless Residential Gateway
Wireless Enterprise Gateways
A wireless Enterprise gateway serves as a gateway to the corporate network, for WLAN users attached to one or many access points. Centralized authentication of WLAN users is an important part of the gateway’s function. Enterprise gateways also can provide functions such as Quality of Service (QoS) and profile management which is a necessity for large-scale wireless deployments.
Networking with a Wireless Enterprise Gateway
The gateway device must be powerful enough and have enough Ethernet connectivity, to support potentially many access points. It may also have to support multiple wireless technologies, besides 802.11. Enterprise gateways may be so complex that taking a “How-to” course before purchase is highly recommended. And, as you might guess, they are also quite expensive. Following is a typical Enterprise network with a wireless gateway:
Wireless NICs
In this section, client device refers to devices such as PCs or PDAs, which can be wireless enabled by adding a wireless NIC. It does not refer to devices like wireless workgroup bridges, which come with wireless built-in as part of its basic functionality.
Wireless NICs are available for client devices in several form factors, including the following:
- PCMCIA (PC Card) and Compact Flash (CF) cards – Actually, these two are the only physical formats for radio cards that are manufactured. All other form factors use one of these two types for the radio. PC Card radios are used directly in both laptops and PDAs. They are also attached as the radio for access points, bridges, workgroup bridges, USB adapters, PCI & ISA adapters, and print servers. PC card antennas vary and some are detachable. CF cards are smaller than PC cards and use less power. These are typically used in PDAs.
- Ethernet and Serial Converters – These devices convert either an Ethernet or a serial port to a PCMCIA slot, into which a PC card radio is inserted. The radio is typically purchased separately. These converters are most often used on older equipment. USB Adapters—USB client devices support plug-n-play and they don’t require any additional power. The radio card may be internal and fixed or modular and easily removable. If removable, the radio card may or may not be included with the USB adapter.
- PCI and ISA Adapters – Many PCI devices are also plug-n-play, but the PCI adapter may not include the radio card. ISA adapters will almost certainly not be plug-n-play. It is recommended that the same vendor devices be used for both the adapter and the radio card whenever the radio card must be purchased separately.
Types of Client Wireless Network Interface Cards (NICs)
