After reading the first email I to though I understood all of this. So
myself and a coworker just got on a white board to draw everything out hint
the 5th grade approach :) pictures are always good. But where I got a good
definition of this is in Bruce Caslow's book on page 395 it once again
cleared up everything for me. Take a look at that and maybe that will help
you out.
Tom
Martin
Subject: Re: Doyle on Stub and
Totally Stubby areas [7:34478]
Sent
by:
nobody
02/05/2002
02:24
PM
Please
respond
to
Tom
Martin
Elmer,
There are no bits set, TSSAs are Cisco-proprietary. TSSAs are configured
only on the ABRs. Non-ABRs in the stub area have no idea that they are
in a TSSA.
- Tom
On Tue, 05 Feb 2002 13:59:56 -0500, Cebuano wrote:
> Exactly. And to add to the LSA-confusion, NSSA'a get a default Type 7
> with the command
> nssa no-redistribution default-information-originate. But for purely
> academic reasons,
> I'd like to know what bit is set to inform the neighboring routers in
> the Totally stubby area that "we are now operating in totally stubby
> mode". Because as we all know, with stub the E-bit is set to 1.
>
> Thanks for the replies.
> Elmer
> ----- Original Message -----
> From: "s vermill"
> To:
> Sent: Tuesday, February 05, 2002 12:41 PM Subject: RE: Doyle on Stub and
> Totally Stubby areas [7:34478]
>
>
>> Yes that wording, when directly compared, is a little confusing. But
>> you have the right understanding. Stub areas only summarize the AS
>> external routes, leaving all of the IA routes in tact. Totally stubby
>> areas get
> only
>> one outside route - whether IA or AS external - 0.0.0.0.
>>
>> Put in different terms, I think you can say that stub areas replace
>> type 5 LSAs with a default and totally stubby areas replace both type 5
>> and 3
> LSAs
>> with with a default. I'm not sure that 0.0.0.0 itself exactly fits any
>> of the LSA classifications. Seems to be kind of a hybird type 3/5 LSA.
>>
>> Cebuano wrote:
>> >
>> > Hi, group.
>> > Please clarify this description by Doyle regarding stub and totally
>> > stubby areas. As indicated on page 480... "ABRs at the edge of a stub
>> > area will use Network Summary LSAs [i.e. Type 3?] to advertise a
>> > single default route (destination 0.0.0.0) into the area."
>> >
>> > Then on page 482...
>> > "The ABR of a totally stubby area will block not only AS External
>> > LSAs but also all Summary LSAs - with the exception of a single type
>> > 3 LSA to advertise the default route [i.e. 0.0.0.0, right?]
>> >
>> > So now there doesn't seem to be much difference between the two based
>> > on this
>> > explanation.
>> > I always uderstood that the main difference was that Stub areas get a
>> > default route for areas external to their AS while Totally stubby
>> > areas get a default route for areas external to their own area.
>> >
>> > Please someone clarify me on this.
>> > Thanks.
>> >
>> > Elmer
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