Re: OSPF LSA type 3 filtering

Sarad, Tim or whoever that is interested,

Please download a lab that I wrote on OSPF Filtering, I think you will find
it very useful, it covers many aspects of filtering in OSPF. Let me know
your thoughts.

Download the following files:

http://micronics.nl/OSPF-Filtering.pdf
http://micronics.nl/OSPF-Initial-config.txt

Marko,

Very nice blog, and I agree that there can't be a direct summarization
between non-backbone areas.

On Thu, Jan 3, 2013 at 3:56 AM, Sarad <tosara_at_gmail.com> wrote:

> Hi Brian,
>
> If I understood correctly, as per your explanation area-range and
> filter-list commands come in to effect after ABR construct the type 3 LSA
> to be generated in to the other Area.
>
> When I lab this up I noticed filtering with these commands work differently
> when filter type 3 LSA from one Area to another area. Is there a technical
> explanation for why this happening?
>
> Thanks
> Sara
>
>
>
> On Thu, Jan 3, 2013 at 8:46 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:
>
> > If you want to continue this as a technical discussion that's fine, just
> > don't freak out again after reading my response ;)
> >
> > You said:
> >
> > > What if in area 1 there are some LSA type-1 and type-2? Can you not
> > filter them or summarize them with the "area range" command?
> >
> > No, you can not. This is a fundamentally incorrect notion about OSPF.
> > First, both LSA 1 and 2 are area local scope. The ABR cannot pass them
> > between areas hence there is no filtering or summarization that can
> affect
> > them. Secondly, the *topology* information described by these LSAs is
> > automatically summarized by the ABR into LSA 3. The *reachability*
> > information is not.
> >
> > The reachability information described in multiple LSA 3s can summarized
> > together with the "area range" command. Additionally the reachability
> > information described in LSA 3 can be filtered with either "area range"
> or
> > "area filter-list".
> >
> > "area range" and "area filter-list" do not affect LSAs 1 or 2, they
> affect
> > LSA 3. You can argue this is semantics if you want, but in binary there
> are
> > only two values, TRUE and FALSE.
> >
> >
> >
> > Brian McGahan, CCIE #8593 (R&S/SP/Security)
> > bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>
> >
> > Internetwork Expert, Inc.
> > http://www.INE.com
> >
> > On Jan 3, 2013, at 3:25 AM, "Narbik Kocharians" <narbikk_at_gmail.com
> <mailto:
> > narbikk_at_gmail.com>> wrote:
> >
> > Unbelievable,
> >
> > You are saying that LSA Type-2s don't provide reachability information, I
> > am saying and showing you that they do provide the subnet mask, you then
> > say that you should NOT say LSA filtering because we can not
> theoretically
> > filter LSAs, especially when you are going to take the CCIE lab, let me
> > tell you something, they will probably say "LSA Type 3 Filtering" as the
> > header, they mention that in every Doc CD i have read, now whose
> student/s
> > will miss out on the terminology? You guys use it because it is "commonly
> > used" (Based on Petr) or Cisco says it that way in their DOC-CD, but if I
> > say it, you claim that I do not understand basics of OSPF or routing and
> I
> > should be teaching CCNA.
> >
> > Then, you agree with Paul about my explanation, and then you ask him what
> > does that have to do with "Area range" or the other commands, so why is
> it
> > OK with you to use the term "LSA Filtering" and Not anyone else? Check
> how
> > quick you agreed with Paul, and he was basically repeating what I
> > mentioned, that tells me that you are agreeing with me but you like to
> > argue. I even said at the end of my post "I am not disagreeing with you",
> > but I guess it did not click.
> >
> > Once again, stop doing that. Do you know how to unsubscribe a person from
> > a thread? You are very good with google, try it one more time.
> >
> > On Thu, Jan 3, 2013 at 1:04 AM, Brian McGahan <bmcgahan_at_ine.com<mailto:
> > bmcgahan_at_ine.com>> wrote:
> > You need to relax Narbik. I'm not sure how you made this leap in the
> > discussion, but thanks for once again ruining a potentially helpful and
> > intellectual thread on the list. My apologies if I somehow offended you.
> >
> >
> >
> > On Jan 3, 2013, at 2:34 AM, "Narbik Kocharians" <narbikk_at_gmail.com
> <mailto:
> > narbikk_at_gmail.com>> wrote:
> >
> > You are VERY WRONG. Picking words and acting as though you are an
> attorney
> > did not convince me a bit, but your immaturity is what you definitely
> > proved here today. You are in a routing loop my friend, we made a full
> > circle.
> >
> > Unsubscribe me from further responses. Paul B the owner of this forum
> > forgot to put a disclaimer about people under legal age.
> >
> > If this continues, I will ignore your replies or comments all together,
> or
> > i will be very rude.
> >
> > How do you connect this discussion about my students failing because in
> > many words they attended my class? What does that have to do with this
> > discussion? A student of mine told me that you guys in your volumes say
> > "filtering LSA Type 3", so what gives you the right to use the terms that
> > you disagree with?
> >
> > I even commented in your blog, when Petr wrote an article "ospf route
> > filtering demystified" right after I released a 10 minute VoD on OSPF
> > Filtering, and he admitted in the blog that he uses that same term
> because
> > Cisco uses it in their documentation, but if I use it, I don't know what
> I
> > am talking about? Here incase you forgot:
> > http://blog.ine.com/2009/08/17/ospf-route-filtering-demystified/
> >
> > As I said before unsubscribe me from this thread.
> >
> >
> >
> >
> >
> > --
> > Narbik Kocharians
> > CCSI#30832, CCIE# 12410 (R&S, SP, Security)
> > www.MicronicsTraining.com<http://www.micronicstraining.com/>
> > Sr. Technical Instructor
> > YES! We take Cisco Learning Credits!
> > A Cisco Learning Partner
> >
> >
> > Blogs and organic groups at http://www.ccie.net
> >
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>
>
>

-- 
*Narbik Kocharians
*CCSI#30832, CCIE# 12410 (R&S, SP, Security)
*www.MicronicsTraining.com* <http://www.micronicstraining.com/>
Sr. Technical Instructor
YES! We take Cisco Learning Credits!
A Cisco Learning Partner
Blogs and organic groups at http://www.ccie.net