in
IEOC CCIE Forums

IEOC - INE's Online Community

Welcome to INE's Online Community - IEOC - a place for CCIE and CCENT candidates to connect, share, and learn. Our Online Community features CCIE forums and discussions for all tracks including Routing & Switching, Voice, Security, Service Provider, Wireless,, and Storage. Through these online communities you can discuss your questions with thousands of your peers, hundreds of CCIE's and INE's own team of world renowned CCIE instructors and authors, Brian Dennis - Quintuple CCIE #2210, Brian McGahan – Triple CCIE #8593, Petr Lapukhov - Quad CCIE #16379, and Mark Snow - Dual CCIE #14073.
Latest post 09-14-2015 7:09 AM by Hamood. 6 replies.
Page 1 of 1 (7 items)
Sort Posts: Previous Next
  • 10-04-2014 3:27 PM

    NSSA default-information-originate nssa-only keyword

    The task solution shows the nssa-only keyword being used on R1 and R2 (the ABRs). The rationale in the solution guide is to clear the P-bit and prevent type 7 to type 5 translation.

    When I configure this without the nssa-only keyword, it already appears the P-bit is cleared. I can't think of any reason that the nssa-only keyword is required here. Anyone have any thoughts about this?

    R1#show ip ospf database nssa-external 0.0.0.0
    
                OSPF Router with ID (192.122.3.1) (Process ID 100)
    
                    Type-7 AS External Link States (Area 121)
    
      LS age: 982
      Options: (No TOS-capability, No Type 7/5 translation, DC, Upward)
      LS Type: AS External Link
      Link State ID: 0.0.0.0 (External Network Number )
      Advertising Router: 192.122.3.1
      LS Seq Number: 8000000D
      Checksum: 0x3F27
      Length: 36
      Network Mask: /0
            Metric Type: 2 (Larger than any link state path)
            MTID: 0 
            Metric: 1 
            Forward Address: 0.0.0.0
            External Route Tag: 0
    
      LS age: 1871
      Options: (No TOS-capability, No Type 7/5 translation, DC, Upward)
      LS Type: AS External Link
      Link State ID: 0.0.0.0 (External Network Number )
      Advertising Router: 192.122.3.2
      LS Seq Number: 80000001
      Checksum: 0x5120
      Length: 36
      Network Mask: /0
            Metric Type: 2 (Larger than any link state path)
            MTID: 0 
            Metric: 1 
            Forward Address: 0.0.0.0
            External Route Tag: 0
    
    

    CCIE #45404 (R/S)

    • Post Points: 35
  • 10-05-2014 4:19 AM In reply to

    Re: NSSA default-information-originate nssa-only keyword

    Hi, 

    Same here, it works without nssa-only. I don't really understand what this keyword is for in the context of just defining the area. 

    • Post Points: 5
  • 10-06-2014 9:48 AM In reply to

    • JoeM
    • Top 10 Contributor
    • Joined on 04-15-2012
    • Guadalajara, Mexico
    • Elite
    • Points 31,465

    Re: NSSA default-information-originate nssa-only keyword

    I agree.   There is no reason for the keyword NSSA-ONLY.   The default route is only advertised into the NSSA area.

     

    I looked it up, and here is the CiscoDoc reference of nssa-only.   Now I am curious about when we would actually use this keyword, as it does not seem to be needed for this task.

    EDIT (testing):   I removed the default-info..originate from R2's nssa config. I was thinking that maybe without this, R2 might leak the default-information via E2.   Nope.  R2 does not even receive the default route via R16.

     

    http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_ospf/command/iro-cr-book/ospf-a1.html#wp2730600586

    nssa-only

    (Optional) Limits the default advertisement to this NSSA area by setting the propagate (P) bit in the type-7 LSA t zero.

    • Post Points: 20
  • 10-06-2014 9:52 AM In reply to

    Re: NSSA default-information-originate nssa-only keyword

    From what I read, you can use the nssa-only on an ASBR that is not an ABR. I believe that would be used when you want to originate a default that is outside of OSPF to the NSSA and then not have that default propagated to the rest of the OSPF domain.

    CCIE #45404 (R/S)

    • Post Points: 20
  • 10-06-2014 2:16 PM In reply to

    • plucena24
    • Top 25 Contributor
    • Joined on 03-10-2012
    • Mountain View, CA
    • Elite
    • Points 16,865

    Re: NSSA default-information-originate nssa-only keyword

    @ bengood24 - you are correct. The 'nssa-only' flag is not needed on R1 and R2.  

    The solution for this task has been updated to account for this. 

     

    2xCCIE #38211 (RS/SP)

    • Post Points: 20
  • 08-04-2015 3:22 AM In reply to

    Re: NSSA default-information-originate nssa-only keyword

    The solution was updated but not the solution explanation , which causes a confusion .

     

     

     

    • Post Points: 5
  • 09-14-2015 7:09 AM In reply to

    Re: NSSA default-information-originate nssa-only keyword

    I don't see the wording of this question is clear , it is confusing and the solution explanation as well is not yet updated.

    • Post Points: 5
Page 1 of 1 (7 items)
IEOC CCIE Forums Internetwork Expert CCIE Training
About IEOC | Terms of Use | RSS | Privacy Policy
© 2010 Internetwork Expert, Inc. All Rights Reserved