This read-create value, in seconds, controls how often this router, when acting as Level 2 Designated Intermediate System on a multiaccess network, broadcasts Complete Sequence Number PDUs summarizing its Level 2 LSP database. Other Level 2 routers on the segment compare this CSNP against their own database to spot stale or missing backbone LSPs. An operator managing a large backbone VLAN might raise csIsisCircL2CSNPInterval toward its 600-second maximum once the topology has stabilized, cutting unnecessary CSNP overhead.