Understanding the differences between gateways and routers

The differences between gateways and routers can be confusing. In this article, Brien Posey takes a look at these differences.

For someone who’s new to networking, the differences between gateways and routers can often be confusing. In this article, I’ll attempt to shed some light on these differences.

What they have in common
Before you can talk about the differences between gateways and routers, it’s necessary to understand what they have in common. Both devices are used to regulate network traffic between two or more separate networks. You do this by installing at least two network cards into the device and placing the device between the two networks you’re trying to regulate. This process involves attaching one network card to each network.

And the differences are…
That’s where the similarities end, however. Gateways regulate traffic between two dissimilar networks, while routers regulate traffic between similar networks. The easiest way to illustrate this point is through an example. Suppose you have a Windows 2000 network that’s using TCP/IP as its primary protocol. Because TCP/IP is also the primary protocol of the Internet, you could use a router to connect your network to the Internet. The router would ensure that:
  • ·        Traffic intended for the local network doesn’t bleed onto the Internet.
  • ·        Traffic residing on the Internet that’s not specifically intended for your network stays on the Internet.

Of course, routers can also be used to segment traffic on corporate networks. This feature is useful on really big networks when you need to reduce the amount of traffic flowing across the network. You can use a router to divide the network into segments and thus allow only traffic that’s specifically intended for a different segment to flow across the router.

A gateway, on the other hand, joins dissimilar systems. The best example of a gateway would be a device that joins a PC network with a 3270 mainframe environment or a device that allows a Windows NT network to communicate with a NetWare network. Although a gateway can be used to reduce network traffic, it’s more often used to make communication possible in dissimilar environments.



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