[j-nsp] ispf support on Juniper routers

[Paul Goyette]

The other interesting thing is that the router needs to keep
additional state information in the internal OSPF routing
tables to enable ISPF.  In my opinion, with today's routers,
memory seems to be more of a limitation than CPU horsepower.

Paul Goyette
Juniper Networks Customer Service
JTAC Senior Escalation Engineer
Juniper Security Incident Response Team
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> -----Original Message-----
> From: Chris Whyte 
> Sent: Monday, March 09, 2009 9:31 PM
> To: Phil Mayers; Paul Goyette
> Cc: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] ispf support on Juniper routers
> 
> As just a side note... What's interesting about this 
> so-called feature is
> that it gives people the impression that it an important one 
> in order to
> achieve "fast" convergence yet spf calculation times are relatively
> negligible (even in large networks). If fast convergence is 
> important to you
> then the time to update the forwarding table is where people should be
> focusing their effort, imho. This is the true bottleneck. 
> More specifically,
> features that involve the pre-installment of backup next-hops 
> for example.
> 
> Thanks, Chris
> 
> 
> On 3/9/09 4:56 AM, "Phil Mayers" <p.mayers at imperial.ac.uk> wrote:
> 
> > Paul Goyette wrote:
> >> 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.
> > 
> > An extremely comprehensive answer! Thanks for taking the time!
> > 
> > Cheers,
> > Phil
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>