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Configuration Guide - IP Unicast Routing

CloudEngine 12800 and 12800E V200R002C50

This document describes the configurations of IP Unicast Routing, including IP Routing, Static Route, RIP, RIPng, OSPF, OSPFv3, IPv4 IS-IS, IPv6 IS-IS, BGP, Routing Policy, and PBR.

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Setting the Interval for SPF Calculations

Setting the Interval for SPF Calculations


When an OSPF LSDB changes, the shortest paths need to be recalculated. If a network changes frequently, shortest paths are calculated frequently, consuming many system resources and degrading the system performance. By configuring an intelligent timer to set a proper interval for SPF calculations, you can prevent excessive consumption of system memory and bandwidth resources.


  1. Run system-view

    The system view is displayed.

  2. Run ospf [ process-id ]

    The OSPF process view is displayed.

  3. Run spf-schedule-interval{ interval1 | intelligent-timer max-interval start-interval hold-interval [ conservative ] | millisecond interval2 }

    The interval for SPF calculations is set.

    • The parameter interval1 specifies the interval for SPF calculations, in seconds.
    • The parameter intelligent-timer indicates that an intelligent timer is used to set the interval for SPF calculations.
    • The parameter max-interval specifies the maximum interval for SPF calculations, in milliseconds.
    • The parameter start-interval specifies the initial interval for SPF calculations, in milliseconds.
    • The parameter hold-interval specifies the hold interval for SPF calculations, in milliseconds.
    • The parameter millisecond interval2 specifies the interval for SPF calculations, in milliseconds.

    By default, an intelligent timer is enabled. After an intelligent timer is set, the maximum interval for SPF calculations is 5000 ms, the initial interval is 50 ms, and the hold interval is 200 ms.

    The mechanism of the intelligent timer is as follows:

    1. The initial interval for SPF calculations is specified by start-interval.
    2. The interval for the nth (n ≥ 2) SPF calculation is equal to hold-interval x 2(n-2).
    3. When the interval specified by hold-interval x 2(n-2) reaches the maximum interval specified by max-interval, OSPF uses the maxe fanimum interval to perform SPF calculations.
    4. If no flapping occurs within the interval specified by max-interval that starts upon the end of the last SPF calculation, the intelligent timer exits.

    5. If no flapping occurs in the last calculation interval but flapping occurs in the current calculation interval, the SPF calculation is delayed for a period specified by start-interval. After the SPF calculation is complete, the current interval is used for the next SPF calculation.

  4. Run commit

    The configuration is committed.

Updated: 2019-03-21

Document ID: EDOC1000166601

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