Documentation is essential in today’s increasingly complex networks. It provides vital information
that can greatly reduce network downtime. It also provides verification that the network
is operating correctly.
Baseline information on a network is information about the normal operating conditions of a
network. This baseline is used to determine whether a network configuration is set up in the manner
expected and whether it is operating normally. Some of the specific components of the network
baseline are the network configuration tables, the network topology diagrams, the endsystem
configuration tables, and the end-system topology diagrams.
Network configuration tables show the key configuration parameters that are in place on the
network devices. Some typical items included in a network configuration table are device name,
flash memory DRAM, IOS/CatOS, interface number, MAC address, speed, duplex, VLANs,
trunking, IP address, subnet, subnet mask, and routing protocol. Although these are some of the
standard items in a network configuration table, each table will vary based on a device’s type
and on the design of the particular network. In most cases this information is stored in a spreadsheet
or database format, but hard copies should be regularly printed so that information will
always be available in the event of a problem or failure.
Network topology diagrams are graphical representations of the network components, and
in most cases they contain a subset of the data maintained in the network configuration tables.
The topology diagrams are meant to make the network administrator better able to visualize the
path across the network. Some standard items that go into a network topology are device name,
connections between devices, interface name, VLANs, trunking, IP address, subnet mask, and
routing protocols. As is true for the network configuration tables, hard copies of network topology
diagrams should be regularly printed to ensure that information is always available when
the network goes down.
Exam Essentials
Know what a network baseline is and the major components that go into making it. A
baseline is a set of documentation that establishes normal operating conditions on the network.
Some of the key components of a baseline are the network configuration tables, the
network topology diagrams, the end-system configuration tables, and the end-system topology
diagrams.
Know what network configuration tables are and the information they contain. Network
configuration tables are used to record key settings of network devices, as well as other related
information. Some common items included in a network configuration table are device name,
flash information, DRAM, IOS/CatOS, interface number, MAC address, speed, duplex,
VLANs, trunking, IP address, subnet, subnet mask, and routing protocol.
Know what network topology diagrams are and the information they contain. Network
topology diagrams are graphical representations of the network; they are usually built from
many of the same components as the network configuration tables. Some common components
of network topology diagrams are device name, connections between devices, interface name,
VLANs, trunking, IP address, subnet mask, and routing protocols. 1064
IT Certification CCIE,CCNP,CCIP,CCNA,CCSP,Cisco Network Optimization and Security Tips
Creating a Network Topology Diagram
Now that we have explained the purpose and suggested components for a network topology
diagram, let’s go through the steps to create one.
We will begin with an examination of the standard set of symbols used in such diagrams.
By now, most of you will have already seen and know these symbols; they are illustrated in
Figure 34.3. Employing a standard set of symbols for device types helps to ensure that any
new network administrators coming into the environment will be able to easily understand
the documentation.
FIGURE 3 4 . 3 Networking symbols
In most cases, a network topology diagram is created after the network configuration tables
are set up, because the topology diagram uses much of the information contained in the configuration
tables. Figure 34.4 illustrates a sample network topology diagram and its relationship
to some of the information used from the router configuration table.
Similarly, there is also a direct correlation between items on the topology diagram and the
switch network configuration table, as illustrated in Figure 34.5.
Because most of the information that is on the network topology diagram has already been
retrieved and placed in the network configuration tables, relatively few commands are needed
to generate the diagram itself. One command of great assistance is show cdp neighbors. The
Cisco Discovery Protocol (CDP) is a proprietary protocol that identifies directly attached Cisco
devices. This discovery is done at layer 2, so there is no need to have IP connectivity to see the
neighbors. The show cdp neighbor command shows the neighbors that have been learned via
CDP and gives their summary information. More detailed information can be found by using
the show cdp neighbors detail command.
diagram, let’s go through the steps to create one.
We will begin with an examination of the standard set of symbols used in such diagrams.
By now, most of you will have already seen and know these symbols; they are illustrated in
Figure 34.3. Employing a standard set of symbols for device types helps to ensure that any
new network administrators coming into the environment will be able to easily understand
the documentation.
FIGURE 3 4 . 3 Networking symbols
In most cases, a network topology diagram is created after the network configuration tables
are set up, because the topology diagram uses much of the information contained in the configuration
tables. Figure 34.4 illustrates a sample network topology diagram and its relationship
to some of the information used from the router configuration table.
Similarly, there is also a direct correlation between items on the topology diagram and the
switch network configuration table, as illustrated in Figure 34.5.
Because most of the information that is on the network topology diagram has already been
retrieved and placed in the network configuration tables, relatively few commands are needed
to generate the diagram itself. One command of great assistance is show cdp neighbors. The
Cisco Discovery Protocol (CDP) is a proprietary protocol that identifies directly attached Cisco
devices. This discovery is done at layer 2, so there is no need to have IP connectivity to see the
neighbors. The show cdp neighbor command shows the neighbors that have been learned via
CDP and gives their summary information. More detailed information can be found by using
the show cdp neighbors detail command.
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