Re: OSPF : LSA

It's non obvious implementation but in troubleshooting you got to know how
it behaves .. we should understand its behavior for that matter ....

excerpts :

The behavior of an ABR in advertising a Summary (Type 3) LSA into a
non-backbone area (RFC 2328).
-An ABR will only generate a Type 3 LSA if the route is in the routing table
as an Intra-area route or Inter-area route from a different non-backbone
area from the same OSPF process..

Cheerz,

On Sun, Sep 26, 2010 at 5:58 PM, Carlos G Mendioroz <tron_at_huapi.ba.ar>wrote:

> I guess I'm not representative of the audience, but I rather see a 2
> line description of a non obvious implementation detail than a 15 minute
> VoD about it.
>
> Like in the scenario you presented, it may not be obvious but having a
> VL between the ABR and the bottom left router will bring the route there
> "out of nowhere" :)
>
> -Carlos
>
> Narbik Kocharians @ 26/09/2010 4:47 -0300 dixit:
> > I may do a complete VoD for Filtering in OSPF, there are LOTS of other
> > behaviours and technics that are NOT covered in ANY book. Let me see if
> > i have time and i will put something together. Would you guys like this
> > kind of presentation?
> >
> > On Sun, Sep 26, 2010 at 2:27 PM, kamal negi <kamalnegi.81_at_gmail.com
> > <mailto:kamalnegi.81_at_gmail.com>> wrote:
> >
> > Hi Narbik,
> >
> > Thanks a lot for sharing this VoD . It helped a lot ...
> >
> > Carlos :
> >
> > It's exactly happening same way ..
> >
> > In above topology if we have static route for X.X.X.X/32 on A2, its
> > type -3 LSA is removed from Area 12 .. ( from Area 0 to other Area)
> >
> > however in second scenario if we have route on R3 (From other Area
> > to Area 0 ), LSA -3 for X.X.X.X remains intact.
> >
> >
> > Thanks,
> > CCIE R&S
> >
> > On Sun, Sep 26, 2010 at 2:14 AM, Carlos G Mendioroz
> > <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>> wrote:
> >
> > Wow, nice to know.
> >
> > You state that <area 0> to <other area> route propagation is
> > done via
> > redistribution, and so the route has to be in the RIB "owned by"
> > OSPF to
> > be inserted in some non 0 area.
> >
> > The other way around, from <other area> to <area 0>, follows some
> > internal mechanism so it's RIB independant.
> >
> > Thanks,
> > -Carlos
> >
> > Narbik Kocharians @ 25/09/2010 12:58 -0300 dixit:
> > > Your question is NOT basic at all, actually it s pretty
> > advanced, because I
> > > have NOT seen it in any Cisco Press Workbook, or any workbook
> > for that
> > > matter, but I have this scenario plus more in my NEW Boot
> > Camp 2.0
> > > Workbook.
> > >
> > >
> > >
> > > Please download this VoD and watch it, it's ONLY 10 - 15
> > minutes. I have
> > > explained it purely from behaviors perspective.
> > >
> > >
> > >
> > >
> >
> http://www.micronicstraining.com/classes/index.php?dispatch=products.view&pro
> > <
> http://www.micronicstraining.com/classes/index.php?dispatch=products.view&pro
> >
> > > duct_id=29815
> > >
> > >
> > >
> > > BTW, you don t need to login or register and it s totally FREE.
> > >
> > >
> > > On Sat, Sep 25, 2010 at 7:57 AM, kamal negi
> > <kamalnegi.81_at_gmail.com <mailto:kamalnegi.81_at_gmail.com>> wrote:
> > >
> > >> Experts, I have below OSPF topology :
> > >>
> > >>
> > >> A1 -----A2--------------A3------A4
> > >>
> > >> A1 and A2 (Area 12)
> > >> A2 and A3 (Area 0 )
> > >> A3 and A4 (Area 34)
> > >>
> > >> ABR : A2,A3
> > >> Area 12 , Area 34 are regular area
> > >>
> > >> A4 is originating prefix X.X.X.X/32 from Area 4.
> > >>
> > >> On A2 , I have type -3 LSA for X.X.X.X in Area 0 and Area 12
> > >> On A 1 , I have type -3 LSA for X.X.X.X in Area 12
> > >>
> > >> Now If I configure static route for X.X.X.X/32 on A2, Type-3
> > LSA for
> > >> X.X.X.X gets removed from Area 12.. Any particular reason for
> > this behavior
> > >> ? If we have better route, why it stops this LSA into
> > particular area ???
> > >>
> > >> Pardon my ignorance if this question is basic ...
> > >>
> > >>
> > >> Blogs and organic groups at http://www.ccie.net
> > >>
> > >>
> >
> _______________________________________________________________________
> > >> Subscription information may be found at:
> > >> http://www.groupstudy.com/list/CCIELab.html
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >>
> > >
> > >
> > > --
> > > Narbik Kocharians
> > > CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> > > www.MicronicsTraining.com <http://www.MicronicsTraining.com>
> > > Sr. Technical Instructor
> > > YES! We take Cisco Learning Credits!
> > > Training And Remote Racks available
> > >
> > >
> > > Blogs and organic groups at http://www.ccie.net
> > >
> > >
> >
> _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
> > --
> > Carlos G Mendioroz <tron_at_huapi.ba.ar <mailto:tron_at_huapi.ba.ar>>
> > LW7 EQI Argentina
> >
> >
> >
> >
> >
> > --
> > Narbik Kocharians
> > CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> > www.MicronicsTraining.com <http://www.MicronicsTraining.com>
> > Sr. Technical Instructor
> > YES! We take Cisco Learning Credits!
> > Training And Remote Racks available
>
> --
> Carlos G Mendioroz <tron_at_huapi.ba.ar> LW7 EQI Argentina

Blogs and organic groups at http://www.ccie.net
Received on Mon Sep 27 2010 - 19:10:53 ART