Router
Routers
serve several functions. However, they are used primarily
for these three things:
- Connecting
LANs or networks of different media types
- Filtering
broadcasts and multicasts from servers and other
devices
- Providing
firewalls for network security
Because
routers use Layer
3
addresses, which typically have structure, routers can
use techniques (such as address summarization) to build
networks that maintain performance and responsiveness as
they grow in size. By imposing
structure
(usually
hierarchical) on a network, routers can effectively use
redundant paths and determine optimal routes even in
a
dynamically
changing network.
Switches
segment off collision domains while routers create
broadcast domains. Novell servers will broadcast out
their services and network printers will send out
broadcasts telling of their address, etc. Understand that
switch segmenting will not block broadcasts. The more
broadcast packets on a network, the slower the network.
Here
is an illustration of collision and broadcast
domains.
