Like the network configuration table, the network topology diagram can contain a number of
items; its scope will depend on the complexity of the network involved. In its simplest form, a
network topology diagram will only include the devices and the connections between them.
However, in most cases, the diagram will contain much more information. Some common items
are as follows:
Device Name
Connections Between Devices (which can also include circuit numbers on WAN links)
Device Type
Interface Name
Speed
Media Type
MAC Address
VLANs
Trunk
Encapsulation
IP Address
Subnet
Subnet Mask
Routing Protocols
Unlike the network configuration tables, it is quite common for the network topology diagram
to depict a combination of layer 2 and layer 3 devices. This allows for a more complete
view of the interactions in the network and a better overall view of network connectivity. Just
as you do with network configuration tables, however, you need to be careful to incorporate
enough information into the topology diagram without adding too much. These are working
documents; if they become too overloaded with information, their maintenance will be more
difficult. On the other side, you don’t want to be hunting down information in the middle of an
emergency. There is a delicate balance between too much and not enough information.
Another point of note: Unless your network is small, you are not going to be able to fit it into
a single network topology diagram. Typically, you will need to make multiple topology diagrams
that cover separate aspects of the network. Depending on the drawing program you are
using to create the diagrams, you can also link each of these separate topology diagrams
together. In this manner, you can double-click a particular area to see more- or less-detailed
information or move to another segment of the network.