Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

 
 

Reroute LSPs

Routing Director uses Path Computation Element Protocol (PCEP) or Network Configuration Protocol (NETCONF) to learn and discover Label-switched Paths (LSPs) in your network.

Routing Director can automatically reroute LSP based on the following predefined parameters that you set at your organization level:

  • Equal-cost multipath (ECMP) placement method—Routing Director adopts ECMP-based rerouting of LSPs to load balance traffic and increase bandwidth by fully utilizing unused bandwidth on links to the same destination.

    You need to set the ECMP Placement Method parameter. Based on the placement method you select (Random, Least-Filled, and Most-Filled), Routing Director evaluates link metrics, and if there are multiple ECMP path available towards the same destination then Routing Director selects a path based on the user settings.

  • Link utilization threshold—Routing Director automatically reroutes LSP when the utilization of a link exceeds a specified threshold, ensuring optimal network performance and preventing congestion. For automatic rerouting of LSPs, you need to set Link Utilization Threshold and Threshold Rerouting Interval parameters.

    For example, if the link utilization threshold is set at 60%, Routing Director immediately reroutes traffic if the link utilization exceeds this value. Even after the rerouting, if the link utilization is more than 60% , then Routing Director waits for the duration you have specified in Threshold Rerouting Interval (e.g., 3 minutes) before rerouting to avoid constant adjustments for transient traffic spikes.

    Note:

    Besides organization-level settings, you can also set the link utilization threshold at the link level. The link-level setting overrides the organization level settings.

  • Path optimization interval—Routing Director ensures LSPs are routed through the most optimal paths. Even if an LSP is rerouted due to threshold crossing, link failure or topology change, the LSP should return to its optimal path once the congestion is resolved. For Routing Director to reroute LSPs through the most optimal paths, you need to set the Path Optimization Interval parameter.

  • Link Utilization Violation—Routing Director automatically reroutes LSP when the link utilization violation occurs for a specific time duration and count. For automatic rerouting of LSPs, you need to set Threshold Rerouting Interval, Link Utilization Violation Interval and Link Utilization Violation Count parameters.

    For example, if the link utilization violation interval is set to 1 minute and the link utilization violation count is set to 3, Routing Director immediately reroutes traffic if the link utilization violation occurs for 3 consecutive counts with a time period of 1 minute. If only two violations occur, no rerouting will happen.

    For example, if the link utilization violation interval is set to 1 minute and the link utilization violation count is set to 3, Routing Director immediately reroutes traffic if the link utilization violation occurs consecutively with a time period of 1 minute.

    This mechanism prevents unnecessary rerouting due to transient issues, therefore ensuring that only consistent violations lead to rerouting.

  • Tunnel Delay Violation—Routing Director automatically reroutes an LSP with maximum delay value configured, when the tunnel delay violation occurs for a specific time duration and count. For automatic rerouting of LSPs, you need to set Tunnel Delay Violation Interval and Tunnel Delay Violation Count parameters.

    For example, if the tunnel delay violation interval is set to 1 minute and the tunnel delay violation count is set to 3, Routing Director immediately reroutes traffic if the tunnel delay violations occurs for 3 consecutive counts with a time period of 1 minute. If only two violations occur, no rerouting will happen.

    This mechanism prevents unnecessary rerouting due to transient issues, therefore ensuring that only consistent violations lead to rerouting.

    Note:

    If the specified Tunnel Delay Violation Interval is lesser than the LSP Latency Interval (default value is 5 minutes), then the threshold maximum delay rerouting will not happen.

  • Interface Delay Type—Routing director uses delay information from interfaces connected to links and computes the best path for LSPs that are configured with Delay as Routing Method.

    Use the Interface Delay Type field on the Pathfinder Settings section of the Organization Settings page (Settings Menu > System Settings) to choose one of the following for computing path delay: minimum, maximum, or average. The option you choose is applied to the entire topology and is not specific to a link or an interface.

    Routing Director learns about the delay on links from devices on which delay measurement is enabled through BGP-LS. The information received by the device contains maximum, minimum, and average delay values obtained during a measurement period. Based on the option you have chosen for Interface Delay Type (minimum, maximum, or average), Routing Director uses that delay value and computes the best path for LSPs.

To configure the parameters at your organization level:

  1. Click Settings Menu > System Settings on the banner.

    The Organization Settings page appears.

  2. Configure or modify the following pathfinder settings:
    Parameter Description

    ECMP Placement Method

    Select a placement method for equal-cost multipath (ECMP) routing.

    • Random—Randomly selects one of the ECMP paths
    • Least filled—Selects the path with the maximum available bandwidth
    • Most filled—Selects the path with the minimum available bandwidth

    Based on the placement method you opt, Routing Director evaluates link metrics, distributes traffic, and improves bandwidth utilization on multiple links to the same destination.

    Path Optimization Interval

    Specify the interval after which Routing Director must automatically trigger path optimization. To disable automatic path optimization, enter 0 second.

    Range: 0 through 9 minutes (m), hours (h) or days (d).

    Link Utilization Threshold

    Specify the threshold value (in percentage) for link utilization. When traffic on a link exceeds this value, Routing Director reroutes label-switched path (LSPs). If you do not specify a threshold, the LSP is not rerouted. If you specify 0, the links are blocked.

    Range: 0 through 100 percentage.

    Threshold Rerouting Interval

    Specify the minimum interval (in minutes) after which Routing Director reacts to any traffic or delay violations. If you don’t specify an interval, the label-switched path (LSP) is not rerouted in case of a violation.

    Range: 1 through 300 minutes

    Link Utilization Violation Count

    Count refers to the number of times that a violation must occur for a rerouting event to take place.

    Specify the count for the link utilization violation to occur.

    If the link utilization violation occurs consecutively and exceeds the count you have specified here, then Routing Director reacts to the link utilization violation and reroutes the label-switched path (LSP) to an alternative path that meets the link utilization criteria.

    If you don’t specify a count or specify the count as 0, the LSP is not rerouted in case of a violation.

    Ensure that you specify link utilization violation interval when specifying link utilization violation count. The violation count has higher precedence over threshold rerouting interval.

    Range: 1 through 255

    Link Utilization Violation Interval

    Intervals refer to the time period over which consecutive violations must occur for a rerouting event to take place.

    Specify the interval (in minutes) for consecutive link utilization violation to occur.

    Routing Director reacts to the link utilization violation and reroutes the label-switched path (LSP) to an alternative path that meets the link utilization criteria if the time between two consecutive violations do not exceed the time that you have specified here.

    If you don’t specify the interval or specify the interval as 0, Routing Director will not reroute LSP in case of a violation.

    Ensure that you specify link utilization violation count when specifying link utilization violation interval.

    Range: 1 through 300

    Tunnel Delay Violation Interval

    Intervals refer to the time period over which consecutive violations must occur for a rerouting event to take place.

    Specify the interval (in minutes) for consecutive tunnel delay violation to occur.

    Routing Director reacts to the tunnel delay violation and reroutes the label-switched path (LSP) to an alternative path that meets the link utilization criteria if the time between two consecutive violations do not exceed the time that you have specified here.

    If you don’t specify the interval or specify the interval as 0, the LSP is not rerouted in case of a violation.

    Ensure that you specify tunnel delay violation interval when specifying tunnel delay violation count.

    Range: 1 through 300

    Tunnel Delay Violation Count

    Count refers to the number of times a violation must occur for a rerouting event to take place.

    Specify the count for consecutive tunnel delay violation to occur.

    If the tunnel delay violation occurs consecutively and exceeds the count you have specified here, then Routing Director reacts to the tunnel delay violation and reroutes the label-switched path (LSP) to an alternative path that meets the link utilization criteria.

    If you don’t specify a count or specify the count as 0, the LSP is not rerouted in case of a violation.

    Ensure that you specify tunnel delay violation interval when specifying tunnel delay violation count. The Tunnel Delay Violation Interval and Tunnel Delay Violation Count has higher precedence over Threshold Rerouting Interval.

    Range: 1 through 255

    Interface Delay Type

    Choose the preferred interface delay type (minimum, maximum, or average). Routing director uses the chosen interface delay type to determine the best path for LSPs.

    The default value is average.
  3. Click Save to save the settings.
Verify that the settings are saved and close the Organization Settings page.