I spent some more time labbing this up, and documented everything here: http://bippydu.wordpress.com/2012/08/17/ospf-type-4-lsas-who-needs-em/
I think i finally have a handle on it :) Doug Marko Milivojevic <[email protected]> wrote: >Manish, > >RID is *not* an IP address - it's only a 32bit number that looks like >an IP address. > >-- >Marko Milivojevic - CCIE #18427 (SP R&S) >Senior CCIE Instructor - IPexpert > >On Thu, Aug 16, 2012 at 5:49 PM, MANISH <[email protected]> wrote: >> Excellent post Marko >> >> understood now ......huh!!!!!!!! took some time to digest after some >> experimentation >> >> the Key point here is RID of ASBR may *not be a routable ip add*, or if a >> routable ip add may not be advertised in ospf via network command >> and hence when external routes travels to other areas the advertising >> router is still ASBR RID and other areas dont know how to reach that RID >> but ABR knows about the RID of ASBR via TYPE 1 LSA >> >> CONCLUSION: >> if the RID is Non Routable IP Add NO LSA Type 4 is needed basically >> if the RID is a Routable ip add it will be known to other areas via Type 3 >> LSA and Type 4 both >> >> Thanks all.......for helping out >> >> GoodLuck !!!! >> >> >> >> On Wed, Aug 15, 2012 at 12:49 PM, Marko Milivojevic >> <[email protected]>wrote: >> >>> Manish, >>> >>> Have you read the series of articles I wrote on OSPF LSA types? >>> >>> >>> http://blog.ipexpert.com/2010/08/11/quick-look-into-ospf-database-router-lsa/ >>> >>> http://blog.ipexpert.com/2010/09/13/quick-look-into-ospf-database-network-lsa/ >>> >>> http://blog.ipexpert.com/2010/09/15/quick-look-into-ospf-database-summary-lsa/ >>> >>> http://blog.ipexpert.com/2010/09/22/quick-look-into-ospf-database-external-and-asbr-summary-lsa/ >>> >>> http://blog.ipexpert.com/2010/09/27/quick-look-into-ospf-database-nssa-external-lsa/ >>> >>> There's also a pretty good series written by Joe Astorino on our blog >>> that talks specifically about Type 4 LSA: >>> >>> >>> http://blog.ipexpert.com/2009/11/04/ospf-type-4-lsa-the-forward-address-part-1/ >>> >>> http://blog.ipexpert.com/2009/11/11/ospf-type-4-lsa-the-forward-address-part-2/ >>> >>> -- >>> Marko Milivojevic - CCIE #18427 (SP R&S) >>> Senior CCIE Instructor - IPexpert >>> >>> On Tue, Aug 14, 2012 at 6:40 AM, MANISH <[email protected]> >>> wrote: >>> > Hi All, >>> > >>> > can some one please explain me the difference in LSA Type 3 and LSA Type >>> 4 >>> > >>> > as per my understanding >>> > >>> > LSA Type 3 is used for inter area routes ........meaning all the Type 1/2 >>> > inside an area when crosses in to other area will be advertised using >>> type >>> > 3 >>> > >>> > LSA Type 4 is the IP address of ASBR. >>> > >>> > my confusion is if we already know about ip add of ASBR through Type 3 >>> > since every thing gets flooded in to other areas why do we need type 4 >>> > explicitly to define ip add of ASBR. >>> > >>> > >>> > I read many blogs and other sources but still could not undersdtand. >>> > >>> > take a look at this blog explanation, will fa0/0 of R6 not be known to >>> > other areas using type 3 lsa ? >>> > >>> > >>> http://blog.ipexpert.com/2009/11/04/ospf-type-4-lsa-the-forward-address-part-1/ >>> > >>> > >>> > >>> > Thank You. >>> > Manish >>> > _______________________________________________ >>> > For more information regarding industry leading CCIE Lab training, >>> please visit www.ipexpert.com >>> > >>> > Are you a CCNP or CCIE and looking for a job? Check out >>> www.PlatinumPlacement.com >>> > >>> > http://onlinestudylist.com/mailman/listinfo/ccie_rs >>> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> >> http://onlinestudylist.com/mailman/listinfo/ccie_rs >_______________________________________________ >For more information regarding industry leading CCIE Lab training, please >visit www.ipexpert.com > >Are you a CCNP or CCIE and looking for a job? Check out >www.PlatinumPlacement.com > >http://onlinestudylist.com/mailman/listinfo/ccie_rs _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
