Network Topology Diagrams
Network topology diagrams keep track of the location, function, and status of devices on the network. There are two types of network topology diagrams: the physical topology and the logical topology.
Physical Topology
A physical network topology shows the physical layout of the devices connected to the network. It is necessary to know how devices are physically connected to troubleshoot physical layer problems. Information recorded on the diagram typically includes:
- Device type
- Model and manufacturer
- Operating system version
- Cable type and identifier
- Cable specification
- Connector type
- Cabling endpoints
Figure 1 shows a sample physical network topology diagram.
Logical Topology
A logical network topology illustrates how devices are logically connected to the network, meaning how devices actually transfer data across the network when communicating with other devices. Symbols are used to represent network elements, such as routers, servers, hosts, VPN concentrators, and security devices. Additionally, connections between multiple sites may be shown, but do not represent actual physical locations. Information recorded on a logical network diagram may include:
- Device identifiers
- IP address and prefix lengths
- Interface identifiers
- Connection type
- DLCI for virtual circuits
- Site-to-site VPNs
- Routing protocols
- Static routes
- Data-link protocols
- WAN technologies used
Figure 2 shows a sample logical IPv4 network topology. Although IPv6 addresses could also be displayed in the same topology, it may be clearer to create a separate logical IPv6 network topology diagram.