BIER FIB packet handling

Figure: BIER FIB packet handling shows how BIER packets are handled in the FIB.

Figure: BIER FIB packet handling

1. When a BIER packet arrives, the PE checks the label and finds the BIFT for that label and then pops the label.

2. For the incoming BIER header, it walks the bit index and finds the first entry in the BIFT for that bit position.

3. Using a logical ‟AND”, the BIER header is combined with the BIFT bit-mask and forwarded to the neighbor. If there are multiple neighbors, the BIFT is programmed with a single entry, the neighbor with the smallest IP address.

4. Using a logical ‟NOT” on the BIFT bit-mask entry, the PE finds out which bits remain to be processed.

5. Repeat the process until all the BIER header’s bits are processed.