# Disabling and Reenabling Incremental SPF

By default, when changes occur to a type 5 or type 7 LSA, OSPF recalculates new, loop-free routes for only the LSAs that change. When a subset of LSAs in the external link-state database change, a full recalculation is not necessary. However, through the CLI, you can disable incremental SPF so the router can perform a full SPF on all external LSAs in the link-state database.

disable-incremental-external-spf

- Use to disable incremental external SPF on the router. When issued, this command results in a full SPF when an event occurs to trigger an external SPF.
- Example
  host1(config-router)#disable-incremental-external-spf
- Use the no version to reenable incremental SPF on this router.
- See disable-incremental-external-spf