Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > OSPF > Scalability > When and Why Use OSPF Scalability Features
Root: WRM Database > Information Technology > Certifications > CCNA > Routing Protocols > OSPF > SPF Algorithm > When and Why Use OSPF Scalability Features



When and Why Use OSPF Scalability Features


In a network with 900 routers and several thousand subnets, the amount of processing required to run the complex SPF algorithm might cause convergence time to be slow, and the routers might experience memory shortages.

Summary Of Problems:

• A larger topology database requires more memory on each router.
• Processing the larger-topology database with the SPF algorithm requires processing power that grows exponentially with the size of the topology database.
• A single interface status change (up to down or down to up) forces every router to run SPF again!

* In networks with at least 50 routers and at least a few hundred subnets, engineers should use OSPF scalability features to reduce the problems just described (depending on router CPUs/RAM).







References

Odom, Wendell (2008) CCNA ICND2 Official Exam Certification Guide, Second Edition. Indianapolis: Cisco Press.