From: Hobbs (deadheadblues@gmail.com)
Date: Thu Aug 14 2008 - 19:00:53 ART
Daniel (the first one Mr. Yusef), can you post your task and topology? I am
curious to know what is the requirement :)
thanks
On Thu, Aug 14, 2008 at 2:24 PM, Daniel Valle <danielfrvalle@gmail.com>wrote:
> I think the correct question maybe is (Daniel, please correct me I'm
> wrong!)... How not to convert LSA type-7 to type-5 because by default it is
> converted. The P bit is set to one.
>
> I had the same doubt a couple of years ago.
>
> Let me see if this helps. From Jeff Doyle's book:
>
> "The NSSA External LSA has a flag in its header known as the P-bit. The
> NSSA
> ASBR has the option of setting or clearing the P-bit. If the NSSA's ABR
> receives a type 7 LSA with the P-bit set to one, it will translate the type
> 7 LSA into a type 5 LSA and flood it throughout the other areas. If the
> P-bit is set to zero, no translation will take place and the destination in
> the type 7 LSA will not be advertised outside of the NSSA. This option
> allows you to design an NSSA in which the external destinations learned in
> that area are known only in that area."
>
> I got a bit confused with the explanation above because the IOS has the
> command: "area x nssa no-redistribute".
>
> This command only works when the router is altogether an ASBR, ABR, and is
> connected to a NSSA area AND area zero
>
> the diagram below illustrates an example where the "area x nssa
> no-redistribute" does not make any filtering to avoid the RIP route comming
> to area 0.
>
> (RIP)<--R1-->(OSPF NSSA AREA)<--R2-->(OSPF AREA 0)<--R3
>
>
> You cannot filter at R2 the LSA Type-7 which was generated by R1. the only
> way to do it would be ( from the book troubleshooting ip routing
> protocols):
>
> "summary-address x.x.x.x x.x.x.x not-advertise
>
> This summary-address configuration generates a Type 7 LSA that won't be
> translated into a Type 5 LSA by the NSSA ABR.
> "
>
>
> It would only work in this topology: R2 redistributing the RIP routes to
> area 0 and not to nssa area
>
>
> *(RIP)*
> |
> R1-->(OSPF NSSA AREA)<--R2-->(OSPF AREA 0)<--R3
>
>
> Configure the no-redistribution command on an NSSA ABR that's also an ASBR.
> ( R2 in the example)
>
>
>
> Hope this helps,
>
> Daniel Valle
> On 8/13/08, Scott Morris <smorris@internetworkexpert.com> wrote:
> >
> > Are you asking in general, or for a particular lab assignment?
> >
> > "Manually", I'd say that you'll be sitting by a router looking to change
> > things in packets, but that's time consuming and detailed work that
> nobody
> > wants. :)
> >
> > First ask what is the P-bit? Then you may find the answer leaps out a
> > little when looking at a few commands.
> >
> > But a little more context to your question may help me give a better
> answer
> > to you! (Check out RFC 3101)
> >
> > HTH,
> >
> >
> > Scott Morris, CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et al.
> > CCSI/JNCI-M/JNCI-ER
> > Senior CCIE Instructor
> >
> > smorris@internetworkexpert.com
> >
> >
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com <http://www.internetworkexpert.com/>
> > Toll Free: 877-224-8987
> > Outside US: 775-826-4344
> >
> > Knowledge is power.
> > Power corrupts.
> > Study hard and be Eeeeviiiil......
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > daniel.yusuf@nsn.com
> > Sent: Wednesday, August 13, 2008 11:42 AM
> > To: ccielab@groupstudy.com
> > Subject: P-bit in NSSA ABR
> >
> > Hi GS,
> >
> > How to change P-bit in LSA type-7 at NSSA ABR manually... ?
> >
> > Thanks for your response,
> >
> > -daniel
> >
> >
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