North American Network Operators Group
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Re: IGPs in use

  • From: Henk Smit
  • Date: Wed Oct 14 13:11:09 1998
  • Newsgroups: cisco.external.nanog
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.