Re: LSA Type 4 again

i did it

output from R1 when Area 1 is normal area

            OSPF Router with ID (10.10.10.10) (Process ID 1)

                Summary ASB Link States (Area 0)

  Routing Bit Set on this LSA
  LS age: 46
  Options: (No TOS-capability, DC, Upward)
  LS Type: Summary Links(AS Boundary Router)
  Link State ID: 22.22.22.22 (AS Boundary Router address) ===> R3
  Advertising Router: 1.1.1.1
  LS Seq Number: 80000001
  Checksum: 0x6F6F
  Length: 28
  Network Mask: /0
        TOS: 0 Metric: 1

output when Area 1 is NSSA

            OSPF Router with ID (10.10.10.10) (Process ID 1)

  ----- Original Message -----
  From: Narbik Kocharians
  To: Mohamed El Henawy
  Cc: Molomo ; Rick Mur ; ccielab_at_groupstudy.com
  Sent: Monday, September 07, 2009 12:07 AM
  Subject: Re: LSA Type 4 again

  It will be easy to lab it up.

  R1 ------ Area 0 ------ R2 ------ Area 1 ------- R3

  Set area 1 to nssa and configure R3 to redistribute a connected interface.
Then, do a "Show ip ospf da asbr-summ" on R1. Then try it again without having
Area 1 as NSSA and see the difference.

  On Sun, Sep 6, 2009 at 1:03 PM, Mohamed El Henawy <m.henawy_at_link.net>
wrote:

    Hello Molomo ,

    can you plz share the output of the show ?

    ----- Original Message ----- From: "Molomo" <letjedilakopa_at_gmail.com>
    To: "Rick Mur" <rmur_at_ipexpert.com>
    Cc: <ccielab_at_groupstudy.com>
    Sent: Sunday, September 06, 2009 5:50 PM
    Subject: Re: LSA Type 4 again

      Rick,
      Actually I did lab it and it was not permitted,

      R1---area 1--- R2 ---area 0 --- R3 --area 0--- R4--- area 2--- R5

      area 0 backbone
      area 1 normal area
      area 2 is nssa

      R5 ASBR

      on R1 I cannot see the LSA type 4.

      Regards,
      Molomo

      On Sun, Sep 6, 2009 at 4:43 PM, Rick Mur <rmur_at_ipexpert.com> wrote:

        It could be allowed in the NSSA area, but it would have no use.
        You are correct, the ABR generates a type 4 LSA, when it sees type 5
LSA's
        indeed to describe the location of the ASBR.

        Try to lab it up. Create a topology, insert some external routes in
OSPF
        and issue a 'show ip ospf database' on a router within the NSSA and
see if
        you have a type-4 in your database. It's always good to see the
theory

      being

        confirmed in a lab, at least that is what helps me to understand and
        remember the theory.

        --
        Regards,

        Rick Mur
        CCIE2 #21946 (R&S / Service Provider)
        Sr. Support Engineer IPexpert, Inc.
        URL: http://www.IPexpert.com <http://www.ipexpert.com/>

        On 6 sep 2009, at 16:27, Molomo wrote:

         Experts,

          Jeff Doyle says LSA type 4 is allowed in nssa area ( see table
below). I
          would have thought that since LSA 5 is not permitted then no need
to
          generate LSA 4.

          My understanding is , ABR generates LSA 4 based on the type 5, to
describe
          the position of the ASBR.

          Or am I missing something here?

          I have also seen this in Quick Reference Sheet by Anthony Sequeira.

           Table 8-5. LSA types allowed per area type.

          Area Type

          1&2

          3

          4

          5

          7

          Backbone (area 0)

          Yes

          Yes

          Yes

          Yes

          No

          Non-backbone, non-stub

          Yes

          Yes

          Yes

          Yes

          No

          Stub

          Yes

          Yes

          No

          No

          No

          Totally stubby

          Yes

      No[*]<mk:@MSITStore:C:\Documents%20and%20Settings\user\Desktop\R&S%20CC
IE\Rec
      ommended%20Reading\Books\Cisco%20press\Jeff%20Doyle\CCIE_Professional_D
evelop
      ment_Routing_TCPIP,_Volume_I,_Second_Edition.chm::/1587052024/ch08lev1s
ec1.ht
      ml#ch08tn01>

          No

          No

          No

          Not-so-stubby

          Yes

          Yes

          Yes

          No

          Yes

          [*] Except for a single type 3 LSA per ABR, advertising the default
route

          Regards,

          Molomo

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  --
  Narbik Kocharians
  CCSI#30832, CCIE# 12410 (R&S, SP, Security)
  www.MicronicsTraining.com
  Sr. Technical Instructor

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Received on Mon Sep 07 2009 - 00:12:04 ART