Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Configure Routers to Advertise Link Statistics through BGP-LS

You can use Border Gateway Protocol-Link State (BGP-LS) to obtain information about the link delay and link delay variation (variation in the measured delay between consecutive readings) from a network. In the previous releases, the link delay information was obtained from real-time performance monitoring (RPM) probes configured on the routers.

The path computation element (PCE) in Paragon Pathfinder uses the measured link delays to compute the end-to-end LSP delay as a sum of all link delays in an LSP path. If a maximum delay is configured for the LSP and if the computed link delay violates the configured maximum delay, the PCE computes and reroutes the LSP through a path that has a link delay within the configured maximum delay.


You can configure Juniper Networks routers to send measured link delay through BGP-LS only if:

  • Junos OS 21.3 is running on the router.

  • IS-IS protocol is configured on a point-to-point link

To configure a Juniper Networks routers to send the measured delay and delay variation on a link through BGP-LS:

  1. Enable Two-Way Active Management Protocol (TWAMP) on the routers (Router A and Router z) at the ends of the link:
  2. On each router, configure the interfaces on which you want to measure the delay. For example:
  3. If RPM probes are enabled on the routers, disable the RPM probes to ensure that the routers do not send link delay statistics obtained through RPM probes:

    Refer to Configure Routers to Send JTI Telemetry Data and RPM Statistics to the Data Collector for the RPM probes that might be configured on the router.

  4. (Optional) View the measured delay in the traffic engineering database (TED) database and containerized routing protocol daemon (cRPD) by using the following commands:
    • To view the measured delay in the TED database of a router, execute the following command in the router:

      The output lists the average delay, minimum delay, maximum delay, and delay variation in milliseconds (ms) as follows:

    • To view the measured delay received by cRPD, execute the following command in cRPD:The output lists the average delay, minimum delay, maximum delay, and delay variation as follows:
You can view the link delay statistics in the Paragon Automation GUI as follows:
  • Right-click a link label in the network topology (Network > Topology) and select Measured Delay A::Z . The measured delay is listed on the links as shown in Figure 1.
    Figure 1: Measured Link Delay Indicated on Links in the Network Topology
  • The Measured Delay A and Measured Delay Z columns in the Links tab of the Network Information table display the measured delay on respective ends of the link; see Figure 2.
    Figure 2: Measured Delay Displayed in the Network Information Table