Re: OSPF LSA types

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
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-- 
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net