[j-nsp] ispf support on Juniper routers

[Phil Mayers]

Paul Goyette wrote:
> Having just recently looked at this area of the code, I can
> confirm that Juniper runs incremental SPF whenever possible

As I understand it, there are two types of ispf:

  * ISPF where the LSDB changes are type5 LSA i.e. at the leaves of the 
SPF tree, which can be done incrementally. I believe both IOS and JunOS 
do this by default?

  * the "extra" ispf that the Cisco IOS command does, which applies to 
type1/2 LSA changes:

http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/ospfispf.html

Does JunOS do both or only the former?