Re: OSPF LSA types

Divin,

Remember that BB3 will be building a tree outwards. One if its own links
(type 1 LSA) is connected to a transit network. This link will reference the
DR IP address, which can then be used to reference the type 2 LSA (DR IP
address = type 2 LSA link state ID). The type 2 LSA may then used to build
the tree to all other routers connected to that network (shortest path being
followed). Then those various type 1 LSAs can be referenced, which will
contain any loopbacks.

I always try to think of the tree building process, from there you can see
when and what LSAs are needed to complete it.

Bryan Bartik
CCIE #23707, CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com

On Tue, May 5, 2009 at 11:21 AM, ALL From_NJ <all.from.nj_at_gmail.com> wrote:

> Hey Divin and team,
>
> Probably my favorite all time OSPF resource is the OSPF design guide. Not
> that you have to read this ... but a good one indeed.
>
> http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml#t24
>
> Any who ...
>
> On multi-access networks, which routers do routers build a full adj with?
> Which routers do routers build two-way/drother adj with? .... seeing how
> this relationship works provides the key to understanding the updates. Good
> question Divin.
>
> Routers will build full adj with DR and BDRs. A DR will send type 2 LSAs
> to
> describe all the routers on the multi-access network, and distribute
> routing
> information to the other routers on the multi-access network.
>
> So every router sends it's updates to the DR, and the DR sends these out to
> every router ... to your question, type 1 LSAs are flooded throughout an
> area.
>
> Use this command to check and verify this on each router: show ip ospf
> database detail
>
> If you can lab this up, it will be worth the time and effort. Like you
> mention, add a loopack and see where and how it turns up. Good stuff
> Divin.
>
> HTH,
>
> Andrew Lee Lissitz
>
>
>
>
> On Tue, May 5, 2009 at 12:43 PM, Divin Mathew John <divinjohn_at_gmail.com
> >wrote:
>
> > In a Multiaccess network... we have the DR. and he sents LSA2. Now my
> > question is say...
> >
> > MULTIACCESS_Network ------->BB3
> >
> > now...when BB3 learns about any loopback configured on the DROthers
> > which LSA will BB3 use?. According to wht i could make out.. it would
> > be LSA1. but multiaccess network itself will be learnt thru LSA 1 and
> > LSA 2. LSA 1 being trnasited thru the transit network. and LSA2 being
> > orginated by the DR.
> >
> > am i correct?
> >
> > Thanking You
> >
> > Yours Sincerely
> >
> > Divin Mathew John
> > divinjohn_at_gmail.com
> > divin_at_dide3d.com
> > http://www.dide3d.com
> > +91 9945430983
> > +91 9846697191
> > +974 5008916
> > PGP PUBLIC KEY BLOCK @ http://www.dide3d.com/divin_Public_PGP_key.txt
> > Sent from Bangalore, KA, India
> >
> >
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