Re: IGPs in use

[Henk Smit <hsmit () cisco com>]

Tony Li wrote:
> From a theoretical perspective, they both scale exactly the same.  To wit:
> a two level hierarchy, with SPF within each level.  Given ideal conditions,
> one could reasonably build a 160,000 router network with either protocol
> today without too much difficulty (400 nodes per area).
>
> From a practical perspective, the implementation differences and topology
> issues dominate their practical applicability.

  When one compares the complexity of the SPF calculation itself,
 both OSPF and ISIS scale in a similar way.

  The way routing information is packaged in LSAs and LSPs is different.
 They way those LSAs and LSPs are flooded is different too.
 I think these difference are more important when one compares scalability
 between ISIS and OSPF.

     Henk.