ISIS L1 vs L2

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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Received on Wed Nov 28 2012 - 08:54:10 ART