Figure 17-11 VLAN Trunk Ports
Routers
A router is a device that forwards packets between
networks via the network layer of the OSI model (Layer
3). It forwards, or routes, packets based on the IP
address of the destination device. A router also has the
intelligence to determine the best path to reach a
particular network or device. It can determine the next
hop, or routing destination, by using routing protocols
such as Routing Information Protocol (RIP), Open
Shortest Path First (OSPF), and Border Gateway
Protocol (BGP).
What is the difference between a Layer 3 switch and a
router? Both forward packets based on IP address, right?
The difference is pretty straightforward: Whereas a
switch operates within a network, a router connects two
or more networks. It routes packets to go across different
protocols (such as Ethernet and WAN technologies such
as cable, DSL, or satellite). Another difference is that
switches usually have dedicated hardware (ASICs) to
forward packets as they come in. In contrast, routers
need more intelligence to route packets, and this
intelligence is typically provided by software.