Re: Clarification in NSSA

"Jeyanath Minto J - CTD, Chennai." <jeyananthj@CTD.HCLTECH.COM> Sat, 28 June 2003 13:27 UTC

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Date: Sat, 28 Jun 2003 18:52:56 +0530
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From: "Jeyanath Minto J - CTD, Chennai." <jeyananthj@CTD.HCLTECH.COM>
Subject: Re: Clarification in NSSA
To: OSPF@PEACH.EASE.LSOFT.COM
Precedence: list

hi vivek,
   In section 3.2  step (2) clearly mention this. R3 already out from the
List of NSSA border Routers and , now R2's router Id is higher than anyone (
Actually R2 alone in that List ). As result, R2 will translate LSAs.

Cheers
Minto Mascarenhas
**********************************************************************
*  Internet IS for everyone - but it won't be unless WE make it so   *
**********************************************************************

-----Original Message-----
From: Vivek Dubey [mailto:vivek_ospf@REDIFFMAIL.COM]
Sent: Saturday, June 28, 2003 1:44 PM
To: OSPF@PEACH.EASE.LSOFT.COM
Subject: Re: Clarification in NSSA


Hi,
The point krishna is trying to make:
1) R3 goes down
2) R2 gets elected as translator
3) But R2 while translating Type 7 to Type 5
    sees functionally equv Type 5 previously
    translated by R3 (before being stopped).
    Note R3 router id is higher.
    So R2 doesn't originate Translated Type 5.
4) So both R2 and R1 hold Type 5 generated by
    R3 before it went down (no flushing was done
    by R3 before going down).
5) Consequently R1 will loose routes to those
    Type 7 networks (calculated using Translated
    Type 5 by R3).
6) But R2 will hold routes as it is directly connected
    to NSSA area and can use Type 7 for getting to those
    networks.

This can happen in real networks.
Probably Pat can clarify how to handle such
scenarios.

thanks,
vivek


On Fri, 27 Jun 2003 Jeyanath Minto J - CTD, Chennai. wrote :
>hi Krishna,
>     R2 maintain a List of this area's Nssa border Routers and
>ASBR.
>Translator is Elected from this List.
>     so , when u stopped the R3 , R2 removes the R3 from the
>List. And R2
>will elect itself as a Translator ( because R3 is unreachable )
>and
>translate type 7 to Type 5.
>
>
>
>Cheers
>Minto Mascarenhas
>**********************************************************************
>*  Internet IS for everyone - but it won't be unless WE make it
>so   *
>**********************************************************************
>
>-----Original Message-----
> From: Krishna Rao [mailto:ospf_query@REDIFFMAIL.COM]
>Sent: Friday, June 27, 2003 11:50 AM
>To: OSPF@PEACH.EASE.LSOFT.COM
>Subject: Clarification in NSSA
>
>
>Hi
>
>I am basically testing RFC 3101 NSSA implementation. I find
>that
>routes are missing in the Router (not in NSSA area) but is
>conected to the Router in NSSA area through backbone area.
>
>
>Topology Used in Testing
>========================
>   |-------------------------------|
>   |                               |
>   |                               |
>   |                               |
>R1-------------R2---------------R3
>                  |                |
>                  |                |
>                  |                |
>             --------------------------- NSSA area 0.0.0.1
>                         |
>                         |
>                         |
>                         R4
>                         | area 0.0.0.1
>                         |Import External Routes.
>                         |
>
>There are 2 areas in this Topology -
>NSSA area 0.0.0.1 (R2, R3 and R4)
>Remaining all the networks are in backbone area.
>
>R1 is connected to R2 and R3 through backbone area. R2 and R3
>are
>connected through backbone area.
>
>RouterID of R1 10.0.0.1
>RouterID of R2 20.0.0.1
>RouterID of R3 30.0.0.1
>
>R3 is elected as Translator. Import external routes at R4. R1
>holds the external routes.
>
>Now, stop the router R3. R2 takes over as Translator.
>
>BUT, now R1 doesnot hold the external routes.
>
>I expect the R1 to hold the external routes. But as per RFC
>3101
>since R2 holds LSA generated by R3 which is of higher RouterID,
>R2
>doesnot generate Type 5 LSAs. Is it correct. If this is the
>case,
>then R1 would never hold the external routes.
>
>Your response on this would be highly appreciated.
>
>Thanks & Regards
>Krishna
>
>
>
>
>
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___________________________________________________
Click below to experience Sooraj Barjatya's latest offering
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Abhishek Bachchan & Kareena Kapoor http://www.mpkdh.com