1.Well-known mandatory. (must be in all
UPDATE messages)
-ORIGIN
-AS_PATH
-NEXT_HOP
2. Well-known discretionary. (must be implemented and
may or not be in the UPDATE messages)
- LOCAL_PREF
- ATOMIC_AGGREGATE
3. Optional transitive. (should pass it along
peers)
- AGGREGATOR
- COMMUNITY
4. Optional non-transitive. (no pass it along peers)
- MULTI_EXIT_DISC (MED)
- ORIGINATOR_ID