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BFD Session Flapping Occurs Because of Poor Transmission Quality

Publication Date:  2013-01-08 Views:  22 Downloads:  0
Issue Description

As shown in the following networking diagram, two NE40Es are connected through the backbone network. A large number of transmission devices are deployed on the backbone network. A client associates a BFD session with PIS to speed up the network convergence. After the association is complete, BFD flaps on the interface, affecting the services.

 

Handling Process

1.         The on-site Huawei technical support personnel check the BFD session flapping log "BFD/4/STACHG_TODWN" and find that DetectDown is displayed in the Diagnostic field. The BFD session goes Down on the NE40E because the NE40E fails to receive BFD packets within the specified detection time.

2.         They check the BFD configurations on the NE40Es and find that the BFD configurations on both ends are correct. The default interval at which BFD packets are sent is used.

3.         The BFD session flaps for a long time. The on-site Huawei technical support personnel suspect that the problem may result from the poor quality of the transmission devices. As a result, BFD packets fail to reach the peer NE40E within the specified detection time.

4.         The problem is resolved after the interval at which BFD packets are sent is prolonged.

Root Cause

The poor quality in the transmission devices causes the BFD packets to fail to reach the peer NE40E within the detection time. As a result, the BFD session goes Down.

Solution

Prolong the interval at which BFD packets are sent for detection.

Suggestions
Follow the following steps when you deploy BFD on a network: 1. Configure BFD. 2. Set the interval at which BFD packets are sent. 3. Check whether The BFD session flaps based on the BFD logs and perform either of the following steps as needed: 4. If The BFD session flaps, prolong the interval at which BFD packets are sent. 5. If BFD session flapping does not occur for a time, associate the BFD session with PIS.

END