Home
Guardian
User Guide
Information and resources about the main features of Guardian, and the tasks that you can do from the user interface (UI).
Network
Network
The Network page gives you access to multiple pages that show nodes, links, sessions in tabular format and graphs and traffic in a graphical format.
Links
The Links page shows all the links in your environment.
Link availability
A history of events is stored for each link.

Guardian
- Introduction
  An overview of Guardian.
- Installation Guide
  Information and resources on how to install Guardian, and the different options and settings that are available.
- Administrator Guide
  Information and resources about the Administration section of Guardian, and the tasks that you can do in this part of the software.
- User Guide
  Information and resources about the main features of Guardian, and the tasks that you can do from the user interface (UI).
  - Sensors
  - Alerts
  - Assets
  - Queries
  - Smart Polling
  - Arc
  - Network
    - Network
      The Network page gives you access to multiple pages that show nodes, links, sessions in tabular format and graphs and traffic in a graphical format.
      - Nodes
        The Nodes page lets you view all the network nodes in your environment and perform actions on them.
      - Links
        The Links page shows all the links in your environment.
        Link events
        Link events are shown in a graphical format.
        Link availability
        A history of events is stored for each link.
        Configure a link
        The Links page lets you configure links.
        Show alerts for a link
        The Links page lets you show alerts for a selected link.
        Show requested traces for a link
        The Links page lets you show requested traces for a selected link.
        Request a trace for a link
        The Links page lets you request a trace for a selected link.
        Show events for a link
        The Links page lets you show requested traces for a selected link.
        Show captured URLs for a link
        The Links page lets you show captured URLs for a selected link.
        Manage learning for a link
        The Links page lets you manage the learning for a selected node.
        Navigate from a link
        The Links page lets you navigate to related entities from a selected node.
      - Sessions
        A session is established at a certain point in time, and later turned down. An established communication session might involve more than one message in each direction.
      - Graph
        The Graph pages gives a graphical representation of the nodes in the environment.
      - Traffic
        The Traffic page shows charts with information about throughput, protocols, and open transmission control protocol (TCP) connections.
      - Graph controls
        A list of the different control options in the graph view.
  - Process
  - Reports
  - Assertions
  - Time machine
  - Vulnerabilities
  - Administration
  - Personal settings
- Maintenance Guide
  Information about the maintenance tasks of Guardian, to help you administer and maintain the solution in a production environment.
- Print format documentation
  A list of all the print-format documentation that is available for Guardian.

Link availability

A history of events is stored for each link.

Two events are of particular interest for computing availability:

UP - This occurs when an activity is detected on an inactive link
DOWN - This occurs when an active link stops its activity

Each event has a timestamp to track the precise moment of its occurrence.

Guardian computes the total downtime of a link by taking into consideration the history of events within a finite time window. Then, it sums the time spans of all events starting with a DOWN event and ending with an UP event. All links are considered active by default. Therefore, the availability of the link is 100% minus the percentage of the total downtime.

Track availability

The Track availability feature allows an accurate computation of availability. It enables the monitoring of activity on a link at regular intervals, generating extra UP and DOWN events, depending on the detected activity on both sides of the link during the last interval.

We recommend that you select a value greater than the expected link polling time to avoid checks that are too frequent and are likely to produce spurious DOWN events.

link_events generation is disabled by default. To enable it, see the configuration rule shown in Configuration.