At 9:18 PM +0000 7/10/02, Phillip Heller wrote: >On Wed, Jul 10, 2002 at 04:48:30PM -0400, Lupi, Guy wrote: > When you say that OSPF scales very well in a heirarchy, I realize that >there > are a lot of factors involved. Let's assume that all routers in each POP > with the exception of aggregation and core are in NSSA areas to control > LSA's but still be allowed to insert external routes, but obviously the > routers in the core would have to maintain all of the information. How > large can you scale a topology like this? I am not concerned so much with > the number of routers, but with the number of routes. Are we talking about > 8000, 16000, 24000, 40000 routes? I also realize the types of LSA's play a > big part in OSPF, but assuming that your aggregation and core routers were > very high end Juniper or Cisco routers, what would be a general number >using > OSPF? ISIS? > >In a single ospf instance, and without summarization or stubby/nssa >areas, I've seen ~ 4000 subnets. > >With summarization and/or stubby/nssa areas, I've seen as many as 6000. > >n.b. - these above numbers are rounded and are examples observed on >networks that are comprised of very high end routers. > >The key is to carry only infrastructure networks in your igp. Minimize >infrastructure networks in igp by aggregating (ie, redist a static /24 >for all you /30 point-to-point customers). > >Use bgp to carry customer prefixes. > >Networks with 16000 routes in igp are probably on the border of resource >starvation with hardware that is deployed. > >Networks with more than 16000 routes in igp are probably doing something >like redisting bgp into igp, which is always a bad idea. > >--phil
Absolutely excellent guidelines! Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=48555&t=48509 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
