Support Support Downloads Knowledge Base Case Manager My Juniper 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

[M/MX/T-series] BFD behavior when the interface is brought down via CLI or by pulling the cable out

0

0

Article ID: KB24926 KB Last Updated: 25 Jun 2012Version: 1.0
Summary:
This article provides information about the behavior of BFD, when the interface is brought down via CLI or by pulling the cable out.

Symptoms:
  • BFD never has any interface information with it.

  • BFD depends on RPD to provide, create, and destroy sessions.

  • So, the behavior of BFD varies when the interface is brought down via CLI or by pulling the cable out.
Cause:

Solution:
  • When interface is disabled by CLI:

    When the interface is disabled by CLI, the kernel provides the interface down information to RPD. RPD removes the BFD sessions and BFD, in turn, sends out an ADMIN DOWN to the peer. If the interface is not physically down yet, then the ADMIN DOWN packet will reach the peer and it will send ADMIN DOWN to RPD.

    As per the standard, RPD should not act on ADMIN DOWN; so OSPF is not brought down. When the interface is brought down via CLI, it takes a few milliseconds to bring down the interface. In case of the GRE tunnel being disabled, the interface was actually down after a few seconds.

  • When interface goes down on its own:

    The physical interface is already down and the kernel provides the interface down information to RPD. RPD removes the BFD sessions and BFD, in turn, sends out ADMIN DOWN to the peer. This packet will never reach the peer, as the interface is already down. At the other end, BFD will not receive packets for detect time and eventually, BFD times out and sends DOWN to RPD. RPD will act on DOWN and bring down OSPF sessions.
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