OSPFv2 SPF Calc Options - iSPF, Partial, Full


I've been getting these mixed up, so maybe this will help someone too:

Incremental SPF - iSPF - Calcs SPF only on what changed. Topological changes (small/minor). 
Ex: New Stub router add, Link failure of link not part of Shortest Path Tree (SPF uses RIDs to calc SPT).

Partial SPF - PRC - Partial Route Calcs - Add/delete/metric change of prefixes (NLRI). No change to SPT. No link changes.
LSAs (those that carry prefix info!): 3, 4, 5, 7 
Ex: External route changes (external to an AREA, NOT just OSPF E1/E2/N1/N2... they weren't very clear on this).
Bonus Pt: Using Redistribution to bring route info into OSPF vs. Intra Area, within an Area. Option to scale single Area OSPF. Less Type 1 and 2 LSAs.

Full - Changes (major) to SPT, must do Full SPF Calc.
LSAs: 1, 2 
Ex: Metric change of link that would cause SPT to change (that would require Calc of alternate links, meaning not a Stub router). 


IS-IS does it a little bit differently, more like OSPFv3, but I'm still new to IS-IS, so I'll leave that for someone else to add to for now.

-Good pts on OSPFv3, IS-IS 


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