At 02:59 PM 5/22/01, Priscilla Oppenheimer wrote:
>One design
>challenge with OSPF that Chuck alluded to is that sometimes a network
>topology doesn't have a good candidate for the area 0 network. If the
>network grew without much concern for hierarchy, there may not be any
>obvious high-speed core that could work as Area O.
Actually that's probably not a good way to distinguish IS-IS and OSPF
because IS-IS designs have a similar caveat. IS-IS has its backbone of L2
routers. All inter-area traffic must go through the backbone.
Don't you just love it when I reply to my own replies? To be honest, I know
very little about IS-IS. IS-IS=0 in my mind. ;-)
Priscilla
>At 12:33 AM 5/22/01, Chuck Larrieu wrote:
> >I rechecked the NANOG archive, and I believe you are correct. It was
several
> >thousand nodes.
> >
> >As to the number of routers theoretically possible in a RIP domain, you
> >might be surprised if you were to think through the math.
> >
> >Take a router. Connect ten routers. Connect ten routers to each of those
> >ten. You can do this seven times, and the max distance from any router on
> >the periphery to any other router on the periphery is 15 hops - seven in
> >and seven out again.
> >
> >10^7 = 10,000,000
> >
> >if that center router began with 100 directly connected routers, the
number
> >grows astronomically, and yet the max diameter would remain 15 hops.
> >
> >the real restraint would be the ability of the router to hold a routing
> >table that big. Along with the problem of convergence. Even if there were
no
> >network problems ever, I bet that sucker would take forever to converge!
> >Literally!
> >
> >Chuck
> >
> >-----Original Message-----
> >From: Curtis Call [mailto:[EMAIL PROTECTED]]
> >Sent: Monday, May 21, 2001 6:38 PM
> >To: Chuck Larrieu
> >Cc: [EMAIL PROTECTED]
> >Subject: RE: How is IS-IS more scalable than OSPF? [7:5207]
> >
> >
> > >BTW, I have been told by folks who work in really big networks that none
>of
> > >the routing protocols scale beyond 4-5K routers. As an interesting
aside,
>a
> > >few weeks ago on NANOG there was a discussion about the largest RIPv1
> > >network in existence. It was revealed that until a year or two ago,
Xerox
> > >used RIPv1 and had a few thousand routers running RIPv1 on the network.
> >
> >
> >I believe that the RIP network you are referring to had a few thousand
> >nodes, not a few thousand routers. I doubt a few thousand routers could
> >handle RIPs max 15 hop limitation.
> >FAQ, list archives, and subscription info:
> >http://www.groupstudy.com/list/cisco.html
> >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
>
>
>________________________
>
>Priscilla Oppenheimer
>http://www.priscilla.com
>FAQ, list archives, and subscription info:
>http://www.groupstudy.com/list/cisco.html
>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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