From: Bhisham Bajaj (bhishambajaj@xxxxxxxxx)
Date: Thu Jan 03 2002 - 03:01:09 GMT-3
I have three are 0, 1,2
1----------0----------2
my are I is a stub are so I will not get las 5 in it
but instead I will get a default route from the abr to
reach the external routes
my are 1 canot have a ASBR in it and cannot have
virtual link
my are 2 has an ASBR in it and is injecting the
external routes ( lsa 5 ) int the back bone
know is it that when I wont the area 1 to have a asbr
int it but not get the routes thar are injected int
area 0 by the asbr of area 2 I will have to configure
are 1 as a NSSA
thank u
Reg
Bhisham
--- Peter van Oene <pvo@usermail.com> wrote:
> OSPF networks have a few major scaling problems. The
> main one is that type
> 5 LSA (external) flood throughout the entire OSPF
> domain. What this means
> is that no matter how many areas you create, your
> type 5's still require
> processing by all your routers. In order to
> constrain this, you can
> create stub areas which restrict the flow of type
> 5's and type 4's such
> that the routers in the area need not to worry about
> processing type
> 5's. However, what happens when you want to push
> some statics into an
> area that you have designated at stub? Essentially,
> you've decided that
> there is no value in flooding a mess of external
> information into the area,
> however, you'd still need to get these few externals
> into OSPF in that
> area. Without NSSA you'd have to make the area a
> normal stub area and
> you'd be able to get your few new type 5's in but
> would also get all of the
> type 5's from the rest of the OSPF domain. However,
> by making it an NSSA,
> you have the ability to inject these few new
> externals as type 7's (which
> look like 5's, just with another name) without
> having to absorb all of the
> type 5's you didn't want in the first place. These
> 7's get translated into
> the rest of the normal OSPF domain at Type 5's all
> is good.
>
> NSSA is a very common option in OSPF networks and is
> definitely worth some
> study time.
>
> Hope this helps.
>
> Pete
>
>
>
> At 07:30 PM 1/2/2002 -0800, Bhisham Bajaj wrote:
> >Hi
> >
> >I am trying to understand the concept of NSSA area
> >
> >I tried to read a few doc on it but did not help
> >
> >Can some one explain me this or guide me to some
> good
> >link for it
> >
> >Thank u
> >bhisham
> >
> >
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