Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

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Segment Routing v6 Configuration Guide for Cisco 8000 Series Routers, Cisco IOS XR Releases

PCEP-Related Timers

Updated: September 8, 2026

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Explains how PCEP timers maintain sessions and control delegated, orphaned, and PCE-initiated SR policies and provides guidance for configuring their operating intervals.

PCEP related timers are configurable parameters that

  • govern the behavior and stability of PCEP sessions and the management of delegated SR policies

  • ensure proper session maintenance, and

  • manage the lifecycle of SR policies initiated or delegated by a PCE.

Types of PCEP-Related Timers:

  • Keepalive timer: This timer specifies the frequency (in seconds) at which keepalive messages are sent from the PCC to its PCE peers. These messages confirm the liveness of the PCEP session. Default: 30 seconds

  • Deadtimer: This timer defines how long (in seconds) remote PCE peers will wait before declaring a PCEP session down if no PCEP messages are received from the PCC. It acts as a session timeout. Default: 120 seconds

  • Delegation timeout: This timer determines the maximum duration (in seconds) a delegated SR policy can remain active on the PCC without an active connection to its delegating PCE. Default: 60 seconds.

  • Initiated orphans timer: This timer specifies the amount of time (in seconds) a PCE-initiated SR policy will remain delegated to a PCE peer that has become unreachable by the PCC. It allows for a grace period for the PCE to reconnect. Default: 180 seconds

  • Initiated state timer: This timer defines the duration (in seconds) a PCE-initiated SR policy will remain programmed and active in forwarding on the head-end, even when it is not currently delegated to any PCE (e.g., after the orphan timer expires). Default: 600 seconds.

How PCE-Initiated SR Policy Timers Operate

Summary

The key components involved in this process are:

  • Path Computation Element (PCE): The entity that initiates and delegates SR policies, for example, PCE A.

  • Segment Routing Policy: The network path definition managed by the PCE, for example, Policy P.

  • Head-end Router (PCC): The device that receives, programs, and manages the delegated SR policy, for example, Head-end N.

  • PCEP Timers: Specifically, the initiated orphans and initiated state timers that govern the policy's lifecycle during PCE unreachability.

The process involves the head-end router using initiated orphans and initiated state timers to either preserve the SR policy through re-delegation or remove it from forwarding if no PCE takes ownership within defined timeframes.

Workflow

These are the stages for PCE-initiated SR policy timers:

  1. Policy Instantiation and Initial Delegation: PCE A instantiates SR Policy P at Head-end N. Head-end N then delegates Policy P to PCE A and programs it into its forwarding plane.

  2. PCE Unreachability Detection: If Head-end N detects that PCE A is no longer reachable, head-end N starts both the initiated orphans and initiated state timers for SR Policy P.

  3. Re-delegation Grace Period: If PCE A reconnects before the orphan timer expires, then SR policy P is automatically delegated back to its original PCE (PCE A). After the orphan timer expires, SR policy P will be eligible for delegation to any other surviving PCE(s).

  4. Policy Removal: If SR policy P is not delegated to another PCE before the state timer expires, then head-end N will remove SR policy P from its forwarding.

Set timer intervals that govern PCEP session behavior and management of PCE-initiated SR policies.

Adjusting these timers allows tailored session management for specific network performance needs. You can configure the timers independently and in any order.

Procedure

  1. Use the timers keepalive command to specify how often keepalive messages are sent from the PCC to its peers.

    The range is from 0 to 255 seconds; the default value is 30.

    Example:

    Router(config-sr-te-pcc)# timers keepalive 30

  2. Use the timers deadtimer command topecify how long the remote peers wait before bringing down the PCEP session if no PCEP messages are received from this PCC.

    The range is from 1 to 255 seconds; the default value is 120.

    Example:

    Router(config-sr-te-pcc)# timers deadtimer 120

  3. Use the timers delegation-timeout command to specify how long a delegated SR policy can remain active without an active connection to its delegating PCE.

    The range is from 0 to 3600 seconds; the default value is 60.

    Example:

    Router(config-sr-te-pcc)# timers delegation-timeout 60

  4. Use the timers initiated orphans command to specify the amount of time that a PCE-initiated SR policy will remain delegated to a PCE peer that is no longer reachable by the PCC,

    The range is from 10 to 180 seconds; the default value is 180.

    Example:

    Router(config-sr-te-pcc)# timers initiated orphans 180

  5. Use the timers initiated state command to specify the amount of time that a PCE-initiated SR policy will remain programmed while not being delegated to any PCE.

    The range is from 15 to 14440 seconds (24 hours); the default value is 600.

    Example:

    Router(config-sr-te-pcc)# timers initiated state 600