TRENDnet TDM-E400 - Manual (Page 77)

Chapter 6. Configuring the System Operating Modes
77
How Routers Work
Routers use a higher-layer protocol than bridges use to determine
how to pass data between two networks. Routers such as the
Ethernet Modem Router operate based on the Internet Protocol and
use IP addresses to identify where to send data.
Unlike a MAC address, an IP address is not permanently
associated with a particular piece of hardware, but is assigned to a
computer by its user (or by an administrator or an automated
mechanism called DHCP). Within a group of networked computers,
a router can associate each PC’s assigned IP address with its MAC
address. When a PC initiates communication through the router
outside the network, the router sends out IP packets to the Internet
on behalf of the PC, revealing only the PC’s IP address. As IP
packets are received in response, the router reconciles the IP
address with the PCs MAC address and sends Ethernet (MAC-
layer) packets on the network for the PC to claim.
Because they use a standardized higher-layer protocol for inter-
network communication, routers can connect two or more networks
even when their underlying MAC-layer protocols differ. Routers are
considered more intelligent and flexible devices than bridges, and
often provide a variety of security and network administration
services based on the IP protocols.
For a more detailed description of how routers pass data, see
Chapter 10.