Scalability Issues
Database Churn
- Both protocols have time-limited database entries and therefore require refreshing
- IS-IS lifetime field is 16 bits, giving 18.7-hour lifetimes (with refresh times close to this)
- OSPF age (counts up) has an architectural lifetime limit of 1 hour (80,000 LSAs yield a refresh every 23 milliseconds)
- ÅgDo-not-ageÅh LSAs are not backward compatible
- DonÅft inject zillions of routes into your IGP