Generating Network Topology in Nectus

Generating Wireless Heat Maps in Nectus

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Generating Wireless Heat Maps

Wireless Heat Map is the visual representation of the wireless signal levels at different locations of specific selected area.

Area can be a building floor or outdoors. We read signal level directly at the antennas of the Wireless APs and calculate signal attenuation with a distance

and overlay resulting signal levels on top of area map with a known dimensions.

In this chapter, you’ll learn how to generate Wireless Heat Maps of any area.

The specific topics we will cover in this chapter are:

  1. Preparing the Background Image
  2. Creating a New L2 Topology
  3. Placing the Background Image and Specifying the Scale
  4. Selecting the Wireless Controller
  5. Expanding the Topology and Selecting Your Access Points
  6. Positioning Wireless APs on the Heat Map

1. Preparing the Background Image

The Background Image shows the physical layout of the area that will be included in the Heat Map.

The image needs to be scaled with equal proportions horizontally and vertically. PNG and JPEG image formats are supported. You will need to be able to enter the corresponding length of the image, in feet, to create an accurate Heat Map.

Create the Background Image before proceeding to Step 2.

2. Creating a New L2 Topology

Once you have the Background Image prepared, you will need to create a new L2 Topology for your Heat Map. To create a new L2 Topology go to the Nectus Home Screen and select Topologies -> Start New L2 Topology.

An empty L2 Topology appears.

3. Placing the Background Image and Specifying the Scale

To place the Background Image in the Topology, click the L2 Topology Settings icon to open the “Settings” dialog box then select the Background tab.

Check the Display Image check box and load the Background Image you created in Step 1.

Enter the horizontal length of the Background Image (in feet) in the Background image length in Feet field.

Once the Background Image is visible in the Topology you can resize and reposition it as desired.

4. Placing the Wireless Controller

Find the Wireless Controller for this area in the Wireless Controllers section of the Sites Panel and drag it onto the Topology.

Click the Settings icon to open the “Settings” dialog box. Select the Wireless tab.

Check Show Wireless APs along with any other options you want displayed on the Heat Map. Nectus includes a large collection of Wireless AP icons you can use to customize the map.

Once you click OK the Heat Map reappears with a color-coded scale of signal levels.

5. Expanding the Topology and Selecting Your Access Points

Now you need to expand the Topology. This displays the Wireless Access Points that are connected to the Wireless Controller. To expand the Topology, right-click the Wireless Controller icon and select Expand L2 Network Topology.

This opens the “Expand L2 Network Topology” dialog box. Select the Wireless tab and expand the All Wireless Controllers list to see the Wireless APs connected to the controllers in the Topology. Check the Wireless APs you want to include in the Heat Map.

Click Generate Topology to add the selected Wireless APs to the Heat Map.

6. Positioning Wireless APs on the Heat Map

Drag each Wireless AP to its physical location on the Background Image. Once you do this, the Heat Map will show wireless coverage for this area.

Network Redundancy Visualization (Pure Art)

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Another piece of art generated by Nectus with a help of D3.JS library. Discovery of small Datacenter was completed under 3 minutes and topology generated under 5 seconds.

Conversion to Visio is supported in Nectus starting  from 1.2.40.

Real-time Device and Link status is overlayed in this  topology making it suitable for NOC level monitoring.

Generating Site Network Topology in Nectus

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Visualizing Network Topology

In this chapter, you’ll learn how to generate a map of the L2 Topology for your site. An L2 Topology shows the physical connections between devices, which can be extremely useful for maintenance and troubleshooting. The topology can display real-time up/down status information along with other relevant information about the site.

The specific topics we will cover in this chapter are:

  1. Generating an L2 Topology
  2. Manipulating the L2 Topology
  3. Changing L2 Topology Settings

Generating an L2 Topology

You can generate an L2 Topology for any site in just a few steps. The devices that appear in this topology are those that were found during the nightly site discovery operation.

1.1 Generate the L2 Topology

Follow these steps to generate the L2 Topology for a site:

  1. In the Sites Panel on the Nectus Home Screen, open Sites and right-click the Site you want to work on.

  1. Click Create L2 topology of this site to open the Generate Topology dialog.

  1. Select the devices you want to appear in the topology then click Generate Topology. After a moment Nectus displays the site’s L2 Topology.

Manipulating the L2 Topology

The L2 Topology displays the physical connections between the devices at the site, along with information about those connections. You can drag the entire Topology around the window, as well as drag and resize individual devices.

Open the Topology toolbar in the top left of the window for the additional options shown here:

Changing L2 Topology Settings

Click Settings in the L2 Topology window to open the Settings dialog and customize the information that appears in the Topology.

Assign the Topology a Title if you plan to reuse it.

In the Device Info tab, check Up-Down Status and the type of alert (Color Alert, Audio Alert) for real-time alerts when a device in the Topology is down. With Color Alerts, both the device that is down, and the title of the Topology will flash red as shown in the Topology image above.

Be sure to click the Save icon in the Topology Toolbar to save your changes.

Topology mapping for SDN OpenFlow networks with Nectus


Nectus can monitor OpenFlow capable devices in the same way as the non-OpenFlow devices.
In this article we will show how Nectus can discover and monitor switches that are SDN OpenFlow ready.
We will use following sample topology  for demonstration with Floodlight OpenFlow controller and three OpenFlow switches: Read more

Building Dynamic Interactive Network Diagrams


This post will cover how Nectus can dynamically build topologies and how you can check various performance statistics.
Nectus gives the possibility to build automatically L2 and L3 topologies based on the discovered devices.
Additionally, it allows the administrator to create custom topologies by dragging on the map the devices that are required to be on the topology. Read more

Integrating Cisco Virtual Internet Routing Lab (VIRL) with Nectus


In this article we will see some of the features of Nectus that can enhance the Virtual Internet Routing Lab (VIRL) experience.
VIRL is Cisco’s network simulation platform where you can run Cisco OS (IOS, IOS XE, IOS XR, NX-OS, ASA) virtual machines and other third party virtual machines (this includes Linux servers, traffic generators and other networking vendors virtual machines) to build topologies for feature testing and validation before introducing them in production.

We will explain some features of Nectus that can complement VIRL to help you visualize better your network.

This is the VIRL topology that will be used:

The devices were started with some predefined configuration that included interface IP configuration, routing protocols (EIGRP, BGP).
VIRL topology is using shared flat network so that each device will get an IP address from network on their GigabitEthernet0/0 interface as their management IP address.

Nectus was installed on a Windows 2016 server that was acting as an OpenVPN client connecting to VIRL server which means that it received an IP address from the range –, thus making the Nectus and the VIRL routers to be in the same subnet.

Once Nectus starts discovering the devices from subnet (as per discoverable subnets configured on Nectus), it builds a list with them categorizing them based on the vendor, type of the device, model of the device.

Based on the information collected through SNMP, Nectus can build L2 and L3 topologies.

This is the L2 topology:

And this is the L3 topology:

One interesting feature that Nectus can do is to give you a visual result of the path between two points in the network.
This is called L3 Path Discovery (for now only available for IPv4). Source IP, source router and destination IP are the input values:

And the result looks like this:

The interesting part is that it can discover asymmetric paths in the network to give a better understanding about how traffic flows in the network.
Another interesting set of features is that you can get real time graphs with the some of the characteristics of the interfaces (utilization, availability, errors, dropped packets, traffic volume).
This is how you can select any of the graphs. This is for utilization:

And the graph looks like this:

Observe that although on when we selected the link that appear to be between R5 and R4, it is actually between R5 and SW2.
The errors graph shows how many RX and how many TX errors are on interface basis:

You can have a consolidated view of the top most utilized interfaces or the interfaces that have the most errors.
By default, there are few network monitoring dashboards (you can create your own to better accommodate your monitoring needs).
The high level dashboard gives you the top interfaces with regards to various interface statistics:

From here, you will get the the list of interfaces:

Nectus can trigger alerts based on any of these interface characteristics.
For testing purposes, the threshold level for interface utilization at which the alarm is triggered was configured at 1%.
Using ping command (between R4 and R5, therefore through SW2), the interface utilization was around 870Kbps and after changing the bandwidth of the interface to 10Mbps

(adding bandwidth knob under interface configuration), this 870Kbps turned out to be around 8.5% interface utilization which means that the alert should have been triggered.
After some time, the graph is adjusted with the new value:

The alerts log shows these type of alerts:

And in this interface utilization, this is the alert:

Another useful information that can be retrieved directly from Nectus using the interface graphs is the interface availability that can quickly give some hints about service interruption.
The graph is selected from the link menu:

And it should show the state of the interface:

Coming back to the default network monitoring dashboards, the information that an interface that is down is captured by both default dashboards. This is the low level dashboard:

As well by the high level dashboard:

Again, there is an alert sent for such events:

There is a history kept for each outage of the interfaces showing for how long the interface was down:

Going further graphs for interface errors and dropped packets are useful to troubleshoot network performance.

And for dropped packets:

Coming back to alerts, Nectus can monitor the CPU usage and trigger alerts as required.

The Device Info menu contains among other CPU usage graphs.

If the CPU usage goes above the threshold, not only you will see this on the graph, but it will also trigger an alert:

Another interesting feature that can help you quickly find all sort of information about the devices in your topology is the Composite Search feature:

It can find various information and for instance, I would like to find where is this IP configured:

And the result is this:

Lastly, one feature that can improve VIRL usability is that Nectus can show on the topology that a link is down

(after the link was shutdown from CLI or went down for other reasons like err-disable).

Suppose you do this on CLI:

R4(config)#int gi0/2
*Dec 29 17:35:29.750: %DUAL-5-NBRCHANGE: EIGRP-IPv6 1: Neighbor FE80::F816:3EFF:FE84:2418 (GigabitEthernet0/2) is down: interface down
*Dec 29 17:35:29.752: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor (GigabitEthernet0/2) is down: interface down
*Dec 29 17:35:31.725: %LINK-5-CHANGED: Interface GigabitEthernet0/2, changed state to administratively down
*Dec 29 17:35:32.725: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down

Then the link will blink on the topology, while VIRL will not show anything with regards to the fact that the interface between the VMs is down:

The up/down status can be enabled from the device settings like this:

Throughout this post, various features of Nectus have shown how Nectus5 can bring value to topologies running in Cisco VIRL.
Of course the same features can be used to know your real/production network better, but it is good to know that you can use Nectus5

to monitor your proof of concept network deployed in VIRL.


Using Nectus for Cisco VIRL Topology monitoring


One of the limitations of VIRL that it does not provide real-time visual Up-Down status for Interfaces in your VIRL topology.

Pairing VIRL with Nectus give you best of both worlds. To allow Nectus to monitor your VIRL topology

enable and configure SNMP on your VIRL routers and ensure L3 reachibility  between your VIRL subnets and

Nectus Server IP address.   Define VIRL subnet in Nectus  “Settings” -> “Network Discovery”  and manually start discovery or

define discovery frequency which can be as low as every 6 min.  After Discovery finishes your should be able to see your VIRL topology in Nectus GUI.

Enable monitoring for Interfaces to allow Nectus to send SNMP polls every 30 sec to each virtual router’s interface.


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Generating Site level network topology with Nectus


This short video shows basic steps to generate site level network topology