CompTIA® Network+ : Installing
And Configuring Routers And Switches
2. Network Installation
2.1 Given a scenario, install and
configure routers and switches.
The most common configuration problems arise out
of switching loops, bad cables, wrong switch/router
port configuration, LAN segmentation, wrong IP subnetting,
etc. In addition to the physical connections, it is
important to configure your network properly. Protocols
such as NAT, PAT, VLAN, PoE , QoS are widely used in
configuring a network. Hence. it is important to know
the types of problems that might occur due to misconfigurations
and QoS will give you options within your net work
Some of these protocols have been explained in the
NAT - Network Address Translation : NAT is very widely
used in computer networking. The NAT router has the
job of translating the inside network IP addresses to
the outside global IP address network (the Internet)
enabling inside devices to talk to outside devices and
vice-versa, but inside devices can only use addressing
consistent with the local network addressing scheme.
Similarly, outside devices cannot use local addressing.
Thus, both inside and outside devices can be referred
to with local or global address versions.
Address Classification - Initially, it would
be a little confusing to understand the terminology
like Inside, Outside, Local, and Global. The figure
attempts to clear the concepts associated with NAT
Inside Global : An inside address seen from
the outside. This is a global, publicly-routable
IP address used to represent an inside device
to the outside world. In a NAT configuration,
inside global addresses are those "real" IP
addresses assigned to an organization for use
by the NAT router.
Inside Local - An address of a device on
the local network, expressed using its normal
local device representation. So for example,
if we had a client on a network using the 10.0.0.0
private address block, and assigned it address
10.0.0.207, this would be its inside local address.
Outside Global : An address of an external
(public Internet) device as it is referred to
on the global Internet. This is basically a
regular, publicly-registered address of a device
on the Internet. In the example above, 126.96.36.199
is an outside global address of a public server.
Outside Local : An address of an external
device as it is referred to by devices on the
NAT Pool : A pool of IP addresses to be used
as inside global or outside local addresses