How do I resolve the DOWN notification on my Direct Connect BFD?

Short description

On AWS Direct Connect connections, BFD quickly detects if there are any issues with the forwarding path. If there are issues, then your eBGP session drops and you receive a DOWN notification.

Resolution

To resolve the DOWN notification you receive on your BFD, complete the following steps:

Troubleshoot the flaps

When your interface goes down, your BFD can also go down. This occurs when a router doesn't get BFD keep-alive packets until the hold down timer expires. Review your BFD logs to check for any occurrence of Detect Timer Expiry.

Note: Asynchronous BFD is automatically turned on for all AWS Direct Connect interfaces on the AWS side. You can't configure BFD settings on the AWS side. When creating a BFD session, the BFD protocol always selects the longer and slower timer.

Troubleshoot constant or intermittent flapping

Run the following show tunnel statistics bfd command to check for the number of BFD packets that are sent and received within a specific data plane tunnel:

Note: The following command is specific to Cisco devices. Make sure to use your vendor-specific commands.

vEdge1# show tunnel statistics bfd

Check the BFD configurations to make sure that BFD is activated on the customer gateway (CGW). Verify that the CGW is sending the packets to BFD.

Perform BFD debugs and packet captures on the CGW.

Related information

FAQ for Bidirectional Forwarding Detection (BFD) (from the Juniper website)

BFD timers explanation of "show bfd session" output (from the Juniper website)

IP Routing: BGP Configuration Guide (from the Cisco website)