Layer 2 Topology and Topology Maps

Automatically discover how your network devices are physically connected, and build custom topology maps to represent any view of your infrastructure.

Overview

Cloudmon provides two complementary topology tools. Layer 2 Topology automatically discovers the physical connectivity between network devices by using a seed device and crawling the network via CDP (Cisco Discovery Protocol) and LLDP (Link Layer Discovery Protocol). Topology Maps are custom, manually built maps that can represent any view of the environment, such as a site layout, a geographic view, a virtualisation environment, or a specific subset of devices.

Navigate to Network → Layer 2 Topology for automatic topology discovery, or to Network → Topology Maps for custom maps.

Layer 2 Topology

Layer 2 Topology discovery starts from a seed device and crawls outward through the network using CDP and LLDP, mapping device connections as it goes. For each discovered device, Cloudmon captures neighbour details via FDP (Foundry Discovery Protocol), IP-to-MAC mappings from the ARP table, and routing path information from the IP Route table. This produces a hierarchical diagram that shows how devices are physically connected across the segment.

Setting Up Layer 2 Topology Discovery

Follow these steps to create your first topology discovery:

1. Ensure prerequisites are met. The probe selected for the scan must be online and reachable from the network segment containing the devices you want to discover. SNMP must be enabled on the seed device and all devices in the scan range. SNMP credentials for the target devices must already be added to Cloudmon under Settings → Configurations → Credentials → SNMP.
2. Navigate to Network → Layer 2 Topology and click the + button to add a new discovery.
3. Fill in the discovery fields as described in the table below.
4. Click Save to create the discovery rule.
5. Click Scan to run the discovery. Cloudmon will contact the seed device and crawl outward through the network using CDP and LLDP.
6. Click the view icon in the topology discovery table to open the discovered topology diagram once the scan completes.

After the Scan

Once the scan completes, click the view icon in the topology discovery table to open the topology diagram. The diagram shows the network as a hierarchical tree with the seed device at the top and downstream neighbours connected below it. Devices already monitored in Cloudmon are colour-coded by status, with green for active and red for inactive. Devices not yet in monitoring are shown in grey and labelled as Not Monitored.

From within the topology diagram you can take the following actions:

• Enable monitoring: Click any unmonitored device and select Monitor to add it to Cloudmon monitoring without leaving the topology view.
• Link a custom map: Click a node and select Link Map to attach a manually created Topology Map to that node. This is useful for devices that cannot be auto-discovered due to lack of CDP or LLDP support.
• Refresh monitoring status: Click the Refresh icon in the side pane to update the status of all devices in the diagram without running a full rescan.
• Rescan: Click the Rescan icon to re-run the discovery and update the topology. Newly added devices and links are added to the existing diagram, and deleted devices and links are marked in red.

Topology Maps

Topology Maps are custom views built manually to represent any grouping of devices or locations that is meaningful to the team. A map can represent a physical site, a geographic view spanning multiple locations, a virtualisation environment, or a specific set of servers. Maps are listed by name and description, and can be created, edited, or removed at any time.

Custom topology maps are useful for teams that need a visual reference tied to a real-world layout, such as a floor plan showing which devices are in which room, or a regional map showing which offices have which infrastructure. They complement the auto-discovered Layer 2 topology by giving teams full control over how their environment is visualised.

Creating a Topology Map

1. Navigate to Network → Topology Maps and click the Add button in the top right corner.
2. Enter a name for the topology map, such as "London Office" or "Production Server Room".
3. Add resources to the map from the available list. Supported resource types include agents, WMI devices, SNMP devices, nodes, services, vCenter, clusters, ESXi hosts, virtual machines, datastores, and resource pools.
4. Position resources by dragging and dropping them onto the map canvas to represent their physical or logical layout.
5. Create links between resources to represent connections or dependencies. Click a resource to initiate a link, then drag the connection to another resource to establish it. For each link you can set a background colour, label colour, and line style (solid or dashed), and choose whether to pull the live interface or node status from the connected devices.
6. Customise the map appearance as needed. You can add a background image such as a floor plan, adjust label colours, and change font sizes for better readability.
7. Click Save to store the topology map.

Once saved, hovering over any resource in the map shows its name, state, type, and IP address. Hovering over a link shows the live interface or node status, IP address, and name. The map reflects real-time monitoring status as device states change.

To attach a custom topology map to a specific node in an auto-discovered Layer 2 topology, navigate to Network → Layer 2 Topology, open the discovered topology, click the node where the map should be linked, select Link Map, choose the map from the dropdown, and click Save.

To display a topology map on a custom dashboard, navigate to Dashboard → Create Dashboard, click Add Widget, select the Topology Maps widget, choose the desired map, and save the dashboard.

Troubleshooting