A topology diagram is a graphical representation of a network. A topology
diagram illustrates how each device in a network is connected, while also
detailing the aspects of its logical architecture. Topology diagrams share many
of the same components as their network configuration table counterparts.
Each network device should be represented on the diagram with consistent
notation or a graphical symbol. Also, each logical and physical connection
should be represented using a simple line or some other appropriate symbol. At
a minimum, most topology diagrams include illustrations of all devices and how
they are connected.
Many topologies also include network cloud symbols.
A labeled cloud symbol is often employed to represent entities that are either
outside the autonomous control of the network or outside the scope of the
topology diagram. The cloud symbols are placeholders signifying that a network,
or collection of networks, exists. It is not particularly relevant to the
diagram to know anything specifically about those networks.
Although the
components of a topology diagram can be restricted to a particular layer of the
TCP/IP model, most often they are a combination of the most important
components of several logical layers. To illustrate the important components at
the network layer of the TCP/IP layer, IP addresses, subnet masks, and routing
protocols might be included.

Some topologies are informal hand-drawn sketches, while others are more
elaborate, using detailed symbols, multiple colors, and different ways to view
them. The latter are typically created using graphics applications that vary in
functionality. While some applications can be used as a solution to manually
create a network diagram, others can automatically create and maintain a
topology of an existing network.
Figure
is an
example of a topology diagram including the device name, interface name, IP
address, and routing protocols. Figure
is an example of
a topology diagram including the device name, interface name, and IP address.