Справочник Пользователя для Wellink Corporation W202ER-4
VisionNet 202ER-4 ADSL Ethernet Router User’s Guide
82
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.
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.
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,
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.
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 VisionNet 202ER-4 provide the
most appropriate path for all your Internet traffic.
or office LAN, the existing routes that set up the default gateways
for your LAN computers and for the VisionNet 202ER-4 provide the
most appropriate path for all your Internet traffic.
On your LAN computers, a default gateway directs all
Internet traffic to the LAN port on the VisionNet 202ER-4.
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.)
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.)
On the VisionNet 202ER-4 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 85.)
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 85.)
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.
more networks or subnets, if you connect to two or more ISP
services, or if you connect to a remote corporate LAN.