BGP attributes are grouped in four separate categories:
Well-known mandatory
Must be supported from all BGP neighbors and
Must be included with every BGP update message.
- Origin
- AS_Path
- Next_Hop
Well-known discretionary
Must be supported from all BGP neighbors but
do not have to be includes in all BGP update messages.
- Local_Preference
- Atomic-Aggregator
Optional transitive
Does not have to be supported by all BGP neighbors, but if present it must be passed to other neighbors.
- Community
Optional non-transitive
Does not have to be supported by all BGP neighbors, but If such an attribute is not recognized, it is ignored and not passed to other neighbors.
- Multi_Exit_Discriminator
- Originator_ID
- Cluster_List