Support Support Downloads Knowledge Base Juniper Support Portal Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

OSPF and ISIS flapping with reason 'InActiveTimer'



Article ID: KB37308 KB Last Updated: 13 Sep 2021Version: 1.0

This article explains why OSPF/ISIS flaps with reason 'InactiveTimer' and the possible scenarios in which this can happen.  A troubleshooting command is provided to quickly narrow down whether the issue is with RPD utilization and/or host queue on the device.


OSPF and ISIS may flap with the following message:

Jun  1 07:06:24  router-name rpd[6987]: %DAEMON-5-RPD_OSPF_NBRDOWN: OSPF neighbor (realm ospf-v2 ae157.0 area state changed from Full to Down due to InActiveTimer (event reason: neighbor was inactive and declared dead)
  1. This is an indication that the consecutive hellos are not received/seen by the local router and the hold time has expired for that particular adjacency/neighbor.

  2. This can happen when the neighbor is indirectly connected to the local router and either the peer is down or there is an indirect link failure.

  3. There is also a possibility the local router received a burst of other control packets at a point where it is not able to handle them, which leads to dropping subsequent hellos for ISIS/OSPF and eventually dropping ISIS/OSPF adjacency.

  4. Another possibility is RPD utilization consistently stays high and ISIS/OSPF protocols are not getting enough cycles to process the hello packets. Then eventually ISIS/OSPF times out.

  1. Check if there are any drops in the net.isr queue with the following sysctl command executed under RE shell:

    % sysctl net.isr.drop

    If drops are seen here,  it indicates either RPD daemon on this device is too busy or the host-path is getting congested.  Continue with the the following troubleshooting steps to narrow down cause.
  2. Check CPU/RPD utilization to see if it spiked to 100% while the ISIS/OSPF adjacency timed out.  For steps to troubleshoot high CPU, refer to the following articles:

  3. Collect the following DDOS output to see if there was any DDOS violation which could have lead to host path being congested.  Troubleshoot based on which protocol is violated.

    >show ddos-protection protocols
    For example, refer to KB35624 - Syslog message - DDOS_PROTOCOL_VIOLATION_SET: Host-bound traffic for protocol/exception exceptions:mtu-exceeded
  4. Check protocol traceoptions for any issues with the hello packets being missed:

    set protocols ospf traceoptions flag all 
    set protocols isis traceoptions flag all

Related Links

Comment on this article > Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search