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Re: OSPF multi-level hierarchy: Necessary at all?
Hmm. THis is the right direction for this discussion - if someone built telephone network over IP technology (even if it's not public internet), he need quite scalable IGP protocol. Through you dont' need plain IGP schema - you have backbone (with 100 - 300 nodes) and regional access networks - every not too large. It can be build just as any ISP+customers. It's not so beautiful as multi-level scheme, but well designed and work just fine (OSPF+IBGP backbone, OSPF+iBGP customers). On Fri, 28 May 1999, Sean Donelan wrote: > Date: Fri, 28 May 1999 3:01:16 -0500 > From: Sean Donelan <[email protected]> > To: [email protected] > Subject: Re: OSPF multi-level hierarchy: Necessary at all? > > > [email protected] (Vadim Antonov) writes: > >Well, actually it is not that bad. The biggest number of locations is > >probably found in AT&T phone network - 250 or so. Sprint is in few > >dozen. The existing IGPs are quite happy with that kind of complexity, > >so if you belong to the "one-router-per-POP" school of thought the > >IGP complexity is a non-issue. > > Well, the phone system is already hierarchial. The top-level is pretty > small, it is the second and third levels which are monsters. > > There are about 100,000 NXX's in the country. California has the largest > state with about 12,000. The Los Angeles LATA is the biggest at about 5,000. > Within PacBell there are about 800 CLLI locations for the Los Angeles LATA, > not including all the other CLECs who may have locations in LA. Getting from > the relatively few IXC access tandems to those 800 locations is the trick. > > I may be doing something wrong, but I've found OSPF gets a bit cranky > with far less than 800 routers and 5,000 routes in an area. > -- > Sean Donelan, Data Research Associates, Inc, St. Louis, MO > Affiliation given for identification not representation > > 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)