3.6.g Implement, troubleshoot and optimize OSPF convergence and scalability

  • 3.6.g [vi] OSPFv3 prefix suppression

Open Shortest Path First version 3 (OSPFv3) can hide the IPv4 and IPv6 prefixes of connected networks from link-state advertisements (LSAs). When OSPFv3 is deployed in large networks, limiting the number of IPv4 and IPv6 prefixes that are carried in the OSPFv3 LSAs can speed up OSPFv3 convergence . The OSPFv3 prefix suppression feature allows you to hide IPv4 and IPv6 prefixes that are configured on interfaces running OSPFv3.

In OSPFv3, addressing semantics have been removed from the OSPF protocol packets and the main LSA types, leaving a network-protocol-independent core. This means that Router-LSAs and network-LSAs no longer contain network addresses, but simply express topology information. The process of hiding prefixes is simpler in OSPFv3 and suppressed prefixes are simply removed from the intra-area-prefix-LSA. Prefixes are also propagated in OSPFv3 via link LSAs.

The OSPFv3 Prefix Suppression feature provides a number of benefits. The exclusion of certain prefixes from advertisements means that there is more memory available for LSA storage, bandwidth and buffers for LSA flooding, and CPU cycles for origination and flooding of LSAs and for SPF computation. Prefixes are also filtered from link LSAs . A device only filters locally configured prefixes, not prefixes learnt via link LSAs. In addition, security has been improved by reducing the possibility of remote attack with the hiding of transit-only networks.

Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 3687-3697).  . Kindle Edition.