Route aggregation combines multiple specific prefixes into one less-specific prefix. This shrinks routing tables.
Example: You own and . Instead of advertising both, advertise .
Benefits:
- Smaller routing tables globally
- Fewer UPDATE messages
- More stable (individual prefix flaps hidden)
Risks:
- Traffic black holes if you aggregate prefixes you don't fully own
- Lose ability to traffic-engineer individual prefixes
ATOMIC_AGGREGATE attribute: Signals that aggregation occurred and path information was lost. AGGREGATOR attribute records who performed it.