• Network topology diagrams
    • Note that it is now common practice to compile network documentation on a website.
    Content 1.2 Network Configuration Documentation 1.2.2 Identifying the components of a network configuration table A network configuration table contains accurate, up-to-date records of the hardware and software used in a network. The network configuration table should provide the troubleshooter with all the information necessary to identify and correct the network fault. When a network configuration table is created for troubleshooting, the contents will vary depending upon the type of device that is documented. A minimum amount of data should be included for all components: Due to the complex nature of most networks, there is a great deal of information that could be recorded. For simplicity and efficiency, network configuration tables should group information based on the layers of the OSI networking model. Network documentation will vary depending on the purpose of the documentation and the types of devices that are being documented. A configuration table constructed for budgetary purposes might include serial number, date of purchase, cost, vendor, and warranty expiration date. These items would not benefit a troubleshooter and should be maintained in separate tables. Configuration table contents will also vary depending on the features implemented on the devices. The Router ID is an important piece of information to record about a router running OSPF. However, the Router ID would not be recorded if only EIGRP was running. Figure displays an example of a network configuration table for a router. Figure documents an example of a network configuration table for a switch.
    Content 1.2 Network Configuration Documentation 1.2.3 Identifying the components of a topology diagram 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.
    Content 1.2 Network Configuration Documentation 1.2.4 Discovering network configuration information The following steps outline the procedure for discovering the network configuration of a router or multilayer switch. Step 1
    View the name and model of the device, as well as the version of operating system that the device is running.
    •     Enter show version. Step 2
    Determine active interfaces and their addresses.
    • Enter show ip interfaces. Step 3
    View a brief summary of the interfaces on the device including the IP address, interface name, media type, status of the configuration, and physical and data link operational status.
    •     Enter show ip interfaces brief. Step 4
    View the MAC address for any interface or port.
    • Enter show ip interface {interface-name} for each interface or enter show interfaces to see a list of all interfaces at once. Step 5
    View a summary of both the IP and non-IP routing protocols enabled for the device.
    • Enter show ip protocols. Step 6
    View details about the spanning tree status on the device.
    • Depending on the IOS version, enter show spanning-tree or show spantree. Step 7
    View a list of directly connected Cisco devices.
    • Enter show cdp neighbors. Step 8
    View details about any connected devices such as IP address and capabilities.
    • Enter show cdp entry {device id}. The following steps outline the procedure for discovering the network configuration of a Layer 2 switch. Step 1
    View the name and model of the device, as well as the version of operating system that the device is running.
    • Enter show version. Step 2
    Determine active ports and their addresses.
    • Enter show interfaces description. Step 3
    View a summary of the ports on the device including port names, port status, duplex, and speed.
    • Enter show interfaces status. Step 4
    View a summary of the EtherChannel configuration on the device.
    • Enter show etherchannel summary. Step 5
    View a summary of the trunk status of any ports that are in trunking mode.
    • Enter show interfaces trunk. Step 6
    View details about the spanning tree status on the device.
    • Depending on the IOS version, enter show spanning-tree or show spantree. Step 7
    View a list of directly connected Cisco devices.
    • Enter show cdp neighbors. Step 8
    View details about any connected devices such as IP address and capabilities.
    • Enter show cdp entry {entry name}. All this information can be displayed using the command show tech-support. However, the output from this command will generate a lot more information than is actually needed.
    Content 1.2 Network Configuration Documentation 1.2.5 Describing the process of creating network documentation For the process of creating network documentation it is recommended that the network configuration table and topology diagram be created together. It is beneficial to create one type of document first, depending on the specific needs and amount of documentation already available.
    Content 1.2 Network Configuration Documentation 1.2.6 Creating network documentation Good network configuration documentation allows rapid discovery of specific information about network devices. Guidelines for creating effective network documentation are: