[j-nsp] ispf support on Juniper routers

[Paul Goyette]

JUNOS will perform ONLY external route recalculation if a
Exzternal (Type-5) or NSSA (Type-7) LSA changes.

JUNOS will perform ONLY inter-area and external route
recalculation if a Network Summary (Type-3) LSA changes,
AND the area from which the LSA originates is NOT known
to be a virtual-link transit area.

JUNOS will perform a full SPF for intra- and inter-area
routes as well as externals for all other LSA changes.

JUNOS does not have Incremental SPF (for intra-area SPF);  
if JUNOS needs to run SPF for intra-area routes, it runs 
a full SPF.


Paul Goyette
Juniper Networks Customer Service
JTAC Senior Escalation Engineer
Juniper Security Incident Response Team
PGP Key ID 0x53BA7731 Fingerprint:
  FA29 0E3B 35AF E8AE 6651
  0786 F758 55DE 53BA 7731 

> -----Original Message-----
> From: Phil Mayers [mailto:p.mayers at imperial.ac.uk] 
> Sent: Monday, March 09, 2009 5:00 AM
> To: Paul Goyette
> Cc: Stefan Fouant; Andrew Jimmy; juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] ispf support on Juniper routers
> 
> 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?
>