Usage Scenario
In an NG MVPN scenario, multicast data flows must be transmitted on a link that has no or few bit errors because even low bit error rates may cause black screen, erratic display, or frame interruption. If multiple links exist between the upstream and downstream nodes of an mLDP tunnel and some links are logical instead of physical direct links, the upstream node randomly selects an outbound interface by default, and sends packets over the link of the selected interface to the downstream node. If you expect the mLDP upstream node to detect bit error rates of the links and switch to an outbound interface that is connected to a downstream link with few or no bit errors, run the bfd bit-error all-interfaces enable command to enable BFD-based bit error detection.
To enable BFD-based bit error detection on an interface, run the
isis bfd bit-error enable command. This function enables BFD to detect bit errors and send bit error information to an IS-IS neighbor. The neighbor can then adjust link costs based on the bit error rates of the links, allowing IS-IS to select a link with no or few bit errors to minimize multicast traffic loss.
Prerequisites
IS-IS has been enabled on the interface using the isis enable command.
Precautions
BFD must be enabled globally using the bfd command in the system view. Otherwise, BFD-based bit error detection does not take effect on the interface.
The isis bfd bit-error enable and
isis bfd bit-error block commands are mutually exclusive and cannot be run in the same interface view.