Skip to main content
Share:
Link is copied

Direct Monitoring Scheme Overview

What is SLA​

In this documentation, an SLA (Service Level Agreement) is a connection monitoring configuration that is set for a virtual receiver and the transmitter connected to it. The setting is applied on the site level.

info

Only Administrator or Manager have the permissions to edit the settings of a virtual receiver and set an SLA scheme for it.

By selecting an SLA option for a virtual receiver, the user sets the values for the following control intervals:

Transmission Paths​

A transmission path is a communication channel that evalink talos uses to receive alarms from a connected transmitter.

The following types of transmitters can be connected to evalink talos:

  • single-path transmitters – transmitters with only one transmission path available, either Ethernet or mobile

  • dual-path transmitters – transmitters with two transmission paths available

    The transmission paths are categorized as follows

    • the primary path – the main path used for sending alarms. In the most typical case, this is an Ethernet path
    • the secondary path – the fallback path to be used if the primary path fails. Typically, this is a mobile path

    See the figure in section Secondary to Primary Path Failover for an illustration.

tip

In the real world, a transmitter can have one, two, or more transmission paths available. A transmitter is considered dual-path in evalink talos when it is connected to its virtual receiver over two transmission paths.

Secondary to Primary Path Failover​

info

The information in this section is relevant to dual-path transmitters only.

Secondary to primary path failover (SecToPrim) is the procedure during which the transmitter detects a connection failure on the primary path, if it occurs, and switches to using the secondary path as a primary one.

After the switch, the transmitter is expected to start polling more frequently on the secondary path to make sure that the polling interval stays within the expected limits – for example, within the site reporting time control interval (see section Connection Monitoring Overview > Site Reporting Time) that is aligned with the regulatory requirements.

evalink talos behavior after a successful SecToPrim is shown on the figure below.

Primary path is disturbed, SecToPrim

If later polling on the primary path returns, the transitter switches back to using the primary path as the main one.

The polling interval value applied on the secondary path in case of SecToPrim (the SecToPrim polling interval) is configurable on the transmitter.

Some transmitters do not support SecToPrim. This means that they cannot detect an issue on the primary path and / or switch automatically to using a different polling interval on the secondary path.

For these transmitters:

  • the polling intervals set for both paths must be sufficient for the case when a path remains the only transmission path available
  • the polling interval on the secondary path must be set to a value that is smaller than the primary path reporting time. For reasons, see section Default SecToPrim Behavior in evalink talos in this article
info

  1. evalink talos controls the polling interval values for Virtual VdS Receiver, Virtual Paradox Receiver, and Virtual TNA Receivers only. For other transmitters, the polling intervals should be set on the transmitter.

  2. The default SecToPrim behavior is described in section Default SecToPrim Behavior in evalink talos in this article. For Virtual VdS Receiver, Virtual Paradox Receiver, and Virtual TNA Receivers, you can configure a SecToPrim behavior that is different from the default one by configuring a Custom DP SLA scheme. For details on configuring a Custom DP, see section Set SLA for a Virtual Receiver > Configure a Custom SLA for a Dual-Path Transmitter.

Default behavior is the behavior that evalink talos applies when SecToPrim occurs if one of the predefined SLA options was selected – for example, DP3 (3m, 25h).

After the primary path failure is reported, evalink talos:

  • sets the secondary path reporting time equal to the primary path reporting time

    For example, if the DP4 (90s, 5h) option was selected in the UI, the secondary path reporting time becomes 90 seconds.

    info

    For Virtual VdS Receiver, Virtual Paradox Receiver, and Virtual TNA Receivers, evalink talos also changes the polling interval on the secondary path. For polling intervals set in this case, see section Default Control Interval Values. The values are provided in the SecToPrim polling interval, sec table column in the relevant transmitter section.

  • waits for the site reporting time

  • when site reporting time is reached, reports the site failure (a CID 350 alarm)

tip

The site reporting time interval length for dual-path transmitters does not equal the primary path reporting time. See section Site Reporting Time on Dual-Path Transmitters for reasons and details.

The primary path reporting time and site reporting time values are set to the default values associated with the predefined SLA option that was selected.

Customize SecToPrim Behavior​

The SecToPrim behavior can be customized by selecting the Custom DP SLA option for a vitrual receiver and setting the appropriate values.

For details on configuring a Custom DP SLA, see section Set SLA for a Virtual Receiver > Configure Custom SLA for a Dual-Path Transmitter.

Examples when customization can be necessary:

  • in case of SecToPrim, the user wants the secondary path reporting time to be a set to a value different from the primary path reporting time
  • the transmitter doesn't support SecToPrim and the user wants wants to mitigate the potential primary path failure by setting small enough secondary path control intervals

Control Interval Lengths​

For a list of control intervals that are set by selecting an SLA scheme, see section Connection Monitoring Overview > Control Intervals.

For details on configuring SLA for a vitrual receiver, see section Set SLA for a Virtual Receiver.

Polling Interval​

Polling interval is the time interval at which keepalive messages are sent on a transmission path.

For the definition of a keepalive message, see section Connection Monitoring Overview > Polling.

In the most typical case:

  • the transmitter polls the receiver. The receiver responds to polling by sending ACK or NACK messages
  • the polling interval is set on the transmitter during installation, and is therefore controlled by the transmitter

There are exceptions:

  • Virtual TNA Receiver and Virtual Paradox Receiver support setting the polling interval value configured in evalink talos to the transmitter

  • Virtual VdS Receiver polls the transmitter itself and therefore controls the polling interval

For these virtual receivers, the polling interval value can be set from evalink talos to the transmitter.

For other virtual receivers, the polling interval values set in evalink talos UI have no effect.

Polling Interval Length​

The polling interval length is set according to the technical and business requirements of the monitored premise.

On dual-path transmitters, different polling intervals are typically set for the primary and secondary paths (see the figure below):

  • for the primary path, it is considered a good practice to set a relatively short polling interval to ensure greater resilience and quicker diagnostics of failures

  • for the secondary path, a larger polling interval is used – this allows, for example, to avoid extra charges if the secondary path is a mobile path

Polling intervals on a dual-path transmitter

If a dual-path transmitter doesn't support secondary to primary path failover, the polling intervals set for both paths must be sufficient for the case when a transmission path becomes the only transmission path available.

For details, see section Set SLA for a Virtual Receiver > How to Set an SLA for a Dual-Path Transmitter without SecToPrim Support.

On single-path transmitters, the considerations for the primary path apply (see above).

warning

For transmitters that maintain a permanent TCP connection with the virtual receiver, the polling interval needs to be smaller than 300 seconds, otherwise the connection is closed by evalink talos. See section Connection Monitoring Overview > Factors that Affect Control Interval Values for details.

Poll Timeout​

The poll timeout is an additional control interval that is used to monitor the polling frequency. Its value equals the polling interval value multiplied by 2.

When this control period is exceeded, if no polling is received on a path, the alive / timed-out status icon for the path in the virtual receiver record in evalink talos UI changes its color. See section Alarm Transmitter Integrations Overview > View Connection Status Indicators on the Virtual Receiver Page for details.

This control interval and its indication in the UI are purely informational.

Path Reporting Time​

A path reporting time is a control interval, after which, if no message is received on a transmission path, evalink talos considers that a path is disconnected and reports the path failure.

The following alarms are used for path failure reporting:

  • for the primary transmission path – a CID 351 alarm
  • for the secondary transmission path – a CID 352 alarm

The path reporting times are controlled by evalink talos in all cases.

Path Reporting Time Length​

The path reporting time length should be set to a reasonable value that allows to avoid sending unnecessary alarms.

At the same time, if the transmitter needs to be certified / comply with security standards, the path reporting times must be set equal to the maximum path reporting time values of the corresponding standard.

tip

For example, transmitters that conform to the EN 50136-1:2012 standard and need to qualify for the DP3 category, must have path reporting times set to:

  • 3 minutes for the primary path – the maximum reporting time for Primary ATP failure. Reporting time
  • 25 hours for the secondary path – the maximum reporting time for Alternative ATP failure. Maximum period when primary failed

See section EN 50136-1:2012 Standard and Swiss Requirements for details.

Site Reporting Time on Dual-Path Transmitters​

This section is relevant to dual-path transmitters only. On single-path transmitters, site reporting time equals the path reporting time of the only available transmission path – for example, 30 minutes for SP3 eth (30m).

For the definition of site reporting time, see section Connection Monitoring Overview > Site Reporting Time.

How Site Reporting Time is Monitored​

In case with dual-path transmitters, site reporting time is the time interval after which ealink talos considers both transmission paths unresponsive and reports the site failure. This happens after:

See the figure below for an illustration.

Both transmission paths are disturbed simultaneously

info
The case when the primary path is disturbed, SecToPrim is performed successfully and then the secondary path also fails after some time, is treated differently. See section Set SLA for a Virtual Receiver > SecToPrim Values Usage for details.

The case when the primary path is disturbed, SecToPrim is performed successfully and then the secondary path remains operational is shown in section Secondary to Primary Path Failover.

Site Reporting Time Length​

Since the secondary path becomes the primary path after SecToPrim, it would be logical to expect the site reporting time to be set equal to primary path reporting time.

However, the underlying Failure of all APTs at the same time limit in the EN 50136-1:2012 standard is set to a larger value. The reason for this is the additional time that is allotted to the transmitter for completing the SecToPrim procedure in hardware. The procedure typically takes around 1 minute.

For Failure of all APTs at the same time limit values associated with various SLA options, see section EN 50136-1:2012 Standard and Swiss Requirements.

Set Site Reporting Time​

Site reporting time is set, implicitly or explicitly, when the user selects an SLA option to be used for the virtual receiver:

  • site reporting time length can be set explicitly for dual-path transmitters by filling in the Reporting time for failure of all paths field while configuring a Custom DP SLA option

    See section Set SLA for a Virtual Receiver > Configure a Custom SLA for a Dual-Path Transmitter for details.

  • site reporting time can be also set implicitly by selecting one of the DP SLA options for a virtual receiver – for example, selecting DP3 (3m, 25h) sets the site reporting time to 4 min (240 sec)

    For default site reporting time values associated with each DP option, see section Default Control Interval Values.

info

When configuring a Custom DP for a transmitter that doesn't support SecToPrim, setting a separate value for site reporting time is not allowed. See section Set SLA for a Virtual Receiver > Configure a Custom SLA for a Dual-Path Transmitter for details. The value is implicitly set equal to the secondary path reporting time.

Share:
Link is copied

Was this page helpful?