From: Brian Dennis (brian@xxxxxx)
Date: Wed Jan 09 2002 - 15:13:47 GMT-3
Wow, looks like everyones going for their CCIE now. Howard is even throwing
his hat into the ring. ;-)
Good luck on your lab Howard.
Brian Dennis, CCIE #2210 (R&S)(ISP/Dial) CCSI #98640
5G Networks, Inc.
bdennis@5g.net
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Howard C. Berkowitz
Sent: Wednesday, January 09, 2002 8:39 AM
To: ccielab@groupstudy.com
Subject: RE: NSSA
I think a large part of the issue is that the questions are being
posed with respect to protocol behavior, without any real clue of the
problem to be solved (i.e., the particular topology in mind).
>comments inline
>
>At 10:54 PM 1/8/2002 +0000, omar guarisco wrote:
>>it's not possible to avoid conversion Type7 to Type5 configure the
>>area NSSA as totally stub using the command on ABR
>
>Sure it is. Although technically, what happens is likely more of a
>filtering of type 5 announcements vs an interpretation of P bit
>settings leading to a decision not to convert type 7's to 5's.
Stating things functionally, it certainly is possible to have an area
be both totally stubby and not-so-stubby. The behavior of such an
area is that it can have an ASBR that obtains external routes, and,
assuming the ASBR does not have ABR functionality, sends the
externals into both the local area and to area 0.0.0.0.
Assume a separate ABR for this area. If the area is totally stubby,
that ABR will inject only a default route.
Having the same physical router as ABR and ASBR is a special case
with additional characteristics. Is this the specific problem, Omar,
you are trying to solve? Or are you trying to have the externals
known only in the nonzero area?
>
>
>>area 1 nssa no-summary
>>
>>so that a default route using LSA type 3 from the ABR
>
>
>Making the area totally stubby removes the inter area routing
>information (Type 3 LSAs) from the area. It has nothing to do with
>externals.
>
>>Another question: How it could be that on a NSSA area a router is
>>ASBR is and also an ABR ??? Moreover that NSSA area won't support
>>virual links
>
>
>I take it you didn't check the link I provided which pictorially
>describes this exact situation. The router is an ABR that has an
>interface in the backbone, and interface in an NSSA area, and
>happens to redistribute some routing information. In this case, it
>wishes not to inject that routing information into the NSSA area,
>but only into the rest of the OSPF domain. I'm completely unaware
>of the relevance of virtual links in this scenario.
>
>Pete
>
I'm guessing the virtual link issue is a general question about
NSSAs, rather than having anything to do with a specific topology. It
is true that an area has to have transit capability to support VL's,
so no type of stubby area will do so.
>
>
>
>
>
>>Thnks for helps
>>Omar
>>
>>
>>
>>>From: Peter van Oene <pvo@usermail.com>
>>>Reply-To: Peter van Oene <pvo@usermail.com>
>>>To: "'ccielab@groupstudy.com'" <ccielab@groupstudy.com>
>>>Subject: RE: NSSA
>>>Date: Tue, 08 Jan 2002 17:33:24 -0500
>>>
>>>The below describes the situation where an ASBR happens to be an NSSA ABR
>>>at the same time. In this case, the desire is to bring externals into
the
>>>network on that router, yet not leak them into the NSSA area. The
>>>no-redistribution command accomplishes that nicely.
>>>
>>>However, I think the original poster was looking more for how to restrict
>>>the Type 7 to Type 5 conversion that the NSSA ABR will perform by
>>>default. In this case, adding a summary address with the not-advertise
>>>option for the prefixes you wish to restrict accomplishes this. The
>>>following link is quite helpful in explaining both of these situations in
>>>some detail.
>>>
>>>http://www.cisco.com/warp/public/104/nssa.html#2c
>>>
>>>Pete
>>>
>>>
>>>
>>>At 01:30 PM 1/8/2002 -0800, Jeongwoo Park wrote:
>>>>Make ASBR into ABR by doing
>>>>router ospf 1
>>>> area 1 nssa no-redistribution
>>>>This way, there will be no type 7 generated
>>>>
>>>>-----Original Message-----
>>>>From: Christian C. Aguillo [mailto:chris_aguillo@alfalak.com]
>>>>Sent: Tuesday, January 08, 2002 4:46 AM
>>>>To: GroupStudy
>>>>Subject: NSSA
>>>>
>>>>Hi Friends,
>>>>
>>>>How can I inject external routes to OSPF via NSSA ASBR wihtout
>>>>conversion of
>>>>the LSA-7 to LSA-5.
>>>>
>>>>Thanks and cheers....
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