Page 192 - CISSO_Prep_ Guide

Switches

Several terms used in network communications are quite broad
and can have several different meanings. Some examples of this
are the terms switches, firewalls, and VPNs. There are many
types of switches with various functions, just as there are several
generations of firewalls, many of which are considerably
different in their function and operation.

Switches are used to connect devices together, and switches
today perform the functions formerly provided by hubs and
bridges (layer two). Switches forward packets to a destination,
can perform routing functions (a layer three switch), address
translation and balancing (layer four), and do load balancing (a
layer seven switch).

Switches can be used to connect networks but also segment and
divide networks through configurations such as a VLAN
(Virtual LAN) where different devices physically connected
onto one switch may be set up to act as completely separate
networks.

Switches can be wired or wireless, small and inexpensive, or
large and very expensive. Each organization must determine
what equipment is suitable to meet its network requirements.

Routers

The purpose of a router is to connect multiple networks together
and forward incoming packets as best it can in the direction of
the destination IP address that is in the packet header. A router
can vary in size from a wireless router in a home that connects
the computers in the home to the internet, to large core routers