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Re: OSPF multi-level hierarchy: Necessary at all?
Btw. Flat network... Routers now have - 128 or 256 MB RAM, 300 - 400 Mhz CPU. I guess you can built flat betwork with 5,000 routers withouth hard problems. Through it's not the question. There is _already_ 2 levels; you can use multi-zone OSPF (independent OSPF networks connected by _redistribute_). The question was _is 2-level hierarchy enougph__? On Fri, 28 May 1999, Alex Zinin wrote: > Date: Fri, 28 May 1999 14:26:27 +0400 > From: Alex Zinin <email@example.com> > To: Vadim Antonov <firstname.lastname@example.org>, email@example.com > Subject: Re: OSPF multi-level hierarchy: Necessary at all? > > > At 11:35 27.05.99 -0700, Vadim Antonov wrote: > >... > >>but the main question is whether there is a demand > >>for it or not. > > > >I guess the answer is pretty much not. The amount of interior > >routing information in a properly designed backbone is quite > >small even if there is no two-layer abstraction. > > If you do not use route-summarization on the area borders, > your're gonna have flat network from the routing info's point > of view, even though the topology info is abstracted. Flat > networks are very well known to be not scalable. > > >(Now, the > >_exterior_ information is aplenty, but OSPF is useless for it > >anyway). > > The new approach could incorporate aggregating externals > on level borders in addition to aggregating internal routing info. > > > > >If someone proposed simplifying and cleaning up OSPF i'd be > >quite for it. Building a protocol allowing to get rid of > >iBGP hack would also help :) > > In OSPFv6 an ASE-LSA can point to another LSA, which per D. Ferguson > can contain BGP path attributes. > The new approach (which could be intergrated in OSPF for IPv6 btw) > could use a technique analogous to this one. > > Rgds > ------------------------------------------------------------------ > Alex D. Zinin, Consultant > CCSI #98966 > CCIE #4015 > AMT Group / ISL > Cisco Systems Gold Certified Partner > http://www.amt.ru > irc: //EFNET/#cisco, //irc.msn.com/#NetCisco [Ustas] > > > Aleksei Roudnev, Network Operations Center, Relcom, Moscow (+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 230-41-41, N 13729 (pager) (+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)