ATL Telecom AM30 - Manual (Page 84)

84 ATL Telecom User Guide
AM30
Hops and gateways
Each time Internet data is passed from one Internet address to another, it is said to take a
hop. A hop can be a handoff to a different port on the same device, to a different device
on the same network, or to a device on an entirely different network.
When a hop passes data from one type of network to another, it uses a gateway. A
gateway is an IP address that provides initial access to a network, just as a switchboard
serves as a gateway to a specific set of phone numbers. For example, when a computer on
your LAN requests access to a company’s web site, your ISP serves as a gateway to the
Internet. As your request reaches its destination, another gateway provides access to the
company’s web servers.
Using IP routes to define default gateways
IP routes are defined on computers, routers, and other IP-enabled devices to instruct them
which hop to take, or which gateway to use, to help forward data along to its specified
destination.
If no IP route is defined for a destination, then IP data is passed to a predetermined default
gateway. The default gateway serves like a higher-level telephone switchboard; it may not
be able to connect directly to the destination, but it will know a set of other devices that
can help pass the data intelligently. If it cannot determine which of these devices provides a
good next hop (because no such route has been defined), then that device will forward the
data to its default gateway. Eventually, a high level device, using a predefined IP route, will
be able to forward the data along a path to its destination.
Do I need to define IP routes?
Most users do not need to define IP routes. On a typical small home or office LAN, the
existing routes that set up the default gateways for your LAN computers and for the
ROUTER provide the most appropriate path for all your Internet traffic.
fOn your LAN computers, a default gateway directs all
Internet traffic to the LAN port on the ROUTER. Your
LAN computers know their default gateway either
because you assigned it to them when you modified
their TCP/IP properties, or because you configured
them to receive the information dynamically from a
server whenever they access the Internet. (Each of
these processes is described in the Quick Start
instructions, Part 2.)
fOn the ROUTER itself, a default gateway is defined to
direct all outbound Internet traffic to a router at your
ISP. This default gateway is assigned automatically by
your ISP whenever the device negotiates an Internet
connection. (The process for adding a default route is
described on page 87.)
You may need to define routes if your home setup includes two or more networks or subnets, if
you connect to two or more ISP services, or if you connect to a remote corporate LAN.