On Thu, Oct 22, 2015 at 12:35 PM, Dave Bell <m...@geordish.org> wrote: > On 22 October 2015 at 19:41, Mark Tinka <mark.ti...@seacom.mu> wrote: >> The "everything must connect to Area 0" requirement of OSPF was limiting >> for me back in 2008. > > I'm unsure if this is a serious argument, but its such a poor point > today. Everything has to be connected to a level 2 in IS-IS. If you > want a flat area 0 network in OSPF, go nuts. As long as you are > sensible about what you put in your IGP, both IS-IS and OSPF scale > very well.
It is rather nice that IS-IS does not require level-2 to be contiguous, unlike area 0 in OSPF. It is a valid topology in IS-IS to have different level-2 areas connected by level-1 areas, though you do have to be somewhat careful about what routes you propagate into-and-back-out-of the intervening level-1 area. But other than that, yeah, the two protocols are pretty much homologous. Matt
