Re: ISIS L1 vs L2

L1/L2 everywhere is not making much sense as you will
have redundant database for both L1 and L2. normally Core you will work L2
edge to "stub" you will do L1/L2 and stub networks you will set L1, L2 will
provide you future flexibility, even if you think that you will not expand
or change, it is not a good design to do a limit yourself from the start,
it does not cost anything to do it L2, but it will cost plenty if you will
need to change Core in future.

my 2 cents :-)

On Wed, Nov 28, 2012 at 3:18 PM, Ronnie Angello <ronnie.angello_at_gmail.com>wrote:

> A single L1/L2 domain would be best as it provides flexibility... That
> way you already have a contiguous L2 domain. If the network grows, it's
> easier to add an L1 routing domain than it is to add an L2 routing domain.
> You just add an L1 IS to the edge and push the L1 domain into the network...
>
> Ronnie
>
> Sent from my iPhone
>
> On Nov 27, 2012, at 10:24 PM, Routing Freak <routingfreak_at_gmail.com>
> wrote:
>
> > Hi all
> >
> > In my customer core network where we had a heated about wither OSPF or
> ISIS
> > and finally ISIS won the race for the core IGP due to some business
> > decision and now my problem here is that when i was designing the network
> > with one large ISIS area with all the linka s L1, everyone opposed me to
> > not to configure L1 and go for L2.
> >
> > I know that L1 is within single area and L2 can be connected across areas
> > and also within a single area and it carries all the routes within L1 and
> > L2.
> >
> > But in my design , i have single large area with all links as L1, what is
> > the problem in that, L1 or L2 it should be the same.
> >
> > I didnt understood what is the logic behind the fact that L1 should not
> be
> > used and L2 should be used.
> >
> > I thought may be when they are forming more areas, then l2 makes sense,
> but
> > they r not going to expand the site with another area, so why not going
> for
> > L1 will suffice the requirement .
> >
> > L1 is within one single area and doesnt know any other routes of other
> area
> >
> > L2 router is one where all the areas merge and exchange routes in one
> > separate area. It can be any area and not area 0 and just all the routers
> > in that particular area should be running L2 adjacency with each other.
> >
> >
> > In one large area, which is better L1 or L2. Any ISIS Experts, be sure to
> > reply to this.
> >
> >
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