From: Joseph Brunner (joe@affirmedsystems.com)
Date: Fri Jan 04 2008 - 12:57:17 ARST
Paul,
Aren't you the guy who was going for the IE just to get the leather jacket?
Well it's a gay cheap-ass made in China leather jacket now, more leatherette
than real leather...
It's not a "cooper" grade bomber anymore....
I'm sending an Armani Leather Bomber to an a professional embroidery place
to get mine done with the CCIE logo and my number, FYI
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Paul
Cosgrove
Sent: Friday, January 04, 2008 6:34 AM
To: Luan Nguyen
Cc: groupstudy
Subject: Re: Good explanation for "area nssa translate"?
A NSSA ASBR creates a type-7 external LSA and sets the forwarding
address. Unlike with other areas ASBRs which only sometimes set this
value, an NSSA ASBRs will always set it.
The NSSA ABR then translates this type-7 LSA into a type-5. While it
will specify itself as the advertising router in the type-5, it includes
the same forwarding address that it received in the ASBRs type-7 LSA.
Routers in different area which receiving the type-5, will check to see
that the forwarding address is accessible via an inter area route. They
will only use the LSA if such a route is found, otherwise it is ignored.
If you have a requirement to suppress type-1 and type-2 LSAs from your
NSSA area into other areas, then you may use area range with the
not-advertise option to filter the unwanted routes. This is the example
given on the cisco link you mentioned but filtering using an area
filter-list or distribute-list etc. can also cause the same issue.
The problem occurs when the route to the forwarding address IP of the
translated type-5 is filtered out, so it no longer advertised into other
areas.
When a receiving router checks the type-5 forwarding address and find it
has no route to that IP, it sees the advertised route as inaccessible
and ignores the type-5 LSA.
If you set the ABR to override the ASBRs forwarding address and instead
specify itself in the forwarding address field (actually using 0.0.0.0
in its advertisement, which is understood to mean itself), then the
other routers will still accept the type-5.
Paul.
Luan Nguyen wrote:
> Can I look at the workbook also? :)
> Would someone kind enough to explain this? I found this:
>
http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chap
ter09186a00804556e5.html
> but I don't see any different with that area XX nssa translate type7
> suppress-fa command. By default, the NSSA ABR already used itself to
> advertise those type5-translated-from-type7 LSA to its neighbors. What
is
> the deal here?
>
> -lmn
>
> On Jan 3, 2008 8:21 PM, Narbik Kocharians <narbikk@gmail.com> wrote:
>
>> Look at the last lab in your OSPF section. From the work book in the
class
>> room.
>>
>> On 1/3/08, Chris Riling <criling@gmail.com> wrote:
>>> Hi Group,
>>>
>>> Does anyone have a good explanation for "area nssa translate"? Frome
>>> the DocCD:
>>>
>>> area nssa translate
>>>
>>> To configure an area as a not-so-stubby area (NSSA) and configure the
>> Open
>>> Shortest Path First (OSPF) Forwarding Address Suppression in Translated
>>> Type-5 LSAs feature, use the *area nssa translate *command in router
>>> configuration mode. To remove the NSSA distinction from the area, use
>> the
>>> *
>>> no* form of this command.
>>>
>>> *area* *area-id* *nssa* *translate type7 suppress-fa *
>>>
>>> no *area* *area-id* *nssa* *translate type7 suppress-fa *
>>> Syntax Description
>>>
>>> *area-id*
>>>
>>> Identifier of the area for which authentication is to be enabled. The
>>> identifier can be specified as either a decimal value or an IP address.
>>>
>>> *translate*
>>>
>>> Translates one type of LSA to another type of LSA. This keyword takes
>>> effect
>>> only on an NSSA area border router (ABR) or NSSA Autonomous System
>>> Boundary
>>> Router (ASBR).
>>>
>>> *type7*
>>>
>>> Translates a Type-7 LSA to a Type-5 LSA. This keyword takes effect only
>> on
>>> an NSSA ABR or an NSSA ASBR.
>>>
>>> *suppress-fa*
>>>
>>> Suppresses the forwarding address of the Type-7 LSAs from being placed
>> in
>>> the Type-5 LSAs. This keyword takes effect only on an NSSA ABR or an
>> NSSA
>>> ASBR.
>>>
>>> Doesn't an NSSA ABR do this by it's very nature? Also, could someone
>>> clarify
>>> when you might use forward address supression?
>>>
>>> Thanks,
>>> Chris
>>>
>>> _______________________________________________________________________
>>> Subscription information may be found at:
>>> http://www.groupstudy.com/list/CCIELab.html
>>>
>>
>>
>> --
>> Narbik Kocharians
>> CCIE# 12410 (R&S, SP, Security)
>> CCSI# 30832
>> www.MicronicsTraining.com
>> Sr. Technical Instructor
>> www.Net-WorkBooks.com
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
-- Paul Cosgrove HEAnet Limited, Ireland's Education and Research Network 1st Floor, 5 George's Dock, IFSC, Dublin 1 Registered in Ireland, no 275301 tel: +353-1-660 9040 fax: +353-1-660 3666 web: http://www.heanet.ie/
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