Mind you - Type 4 LSA really has *nothing* to do with the forward address. They serve entirely different purpose.
Also - I read one of the students in this thread wrote that FA is not present on non-NSSA external routes, i.e. those that have not been translated from Type 5 to Type 7. That's not always true :-) -- Marko Milivojevic - CCIE #18427 (SP R&S) Senior CCIE Instructor - IPexpert On Fri, Aug 17, 2012 at 2:18 PM, Doug Koobs <[email protected]> wrote: > 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 _______________________________________________ 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
