RE: Ospf Rules Regarding NSSA ASBR

From: Clay K Auch \(clauch\) (clauch@cisco.com)
Date: Mon Sep 24 2007 - 11:43:19 ART


Just a suggestion that may save you some time in lab scenarios ...

================= Options for verifying routes =================

1. you can utilize the sub-second hello config (see below:)

http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120limit/120s/120s23/fasthelo.htm#wp1027265

OSPF Fast Hello Packets: Example

The following example configures OSPF fast hello packets; the dead interval is 1 second and five hello packets are sent every second:

interface ethernet 1
 ip ospf dead-interval minimal hello-multiplier 5

======================================

2. you can execute the command "Router#clear ip ospf process" command which then prompts you to make sure you want to clear your processes:

R1#clear ip ospf process
Reset ALL OSPF processes? [no]: yes <cr>

======================================

3. I simply clear the ip routing table when I am expecting to see result that are not evident:

Router#clear ip route *

======================================

HTH

Clay

================
Be like water making its way through cracks. Do not be assertive, but adjust to
the object, and you shall find a way round or through it. If nothing within you
stays rigid, outward things will disclose themselves. -- Bruce Lee
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Han Solo
Sent: Sunday, September 23, 2007 8:52 PM
To: Ash
Cc: CCIE at groupstudy.com
Subject: Re: Ospf Rules Regarding NSSA ASBR

Thanks Ash , thats what I figured. Yes R5 is an ASBR connected to backbone area 0 and , nssa area 10 , R5 is only ASBR , it is running rip and ospf.
I redist rip into ospf , and on R5 issueing a "show ip ospf database" I see all the External Type 5's , which should be converted and sent to area 10 nssa internal routers , this was not occuring , I rebooted it and there it went , I just wasnt sure of the following fact.

1) If I issue a "show ip ospf database" on a ospf asbr which happens to be an asbr for a nssa area , I thought that all the type 5's I see on this asbr should be converted into type 7's and sent to nssa internal routers and show up as type 7's.

tia

On Sun, 23 Sep 2007, Ash wrote:

> NSSA doesn't allow type 5's to be propagated into the area. Question i
> have is, is your R5 OSPF NSSA router an ABR or truly an ASBR?. If its
> an ASBR meaning you have done some sort of redistribution into OSPF on
> R5, then those redistributed routes will show as type 5 in non nssa
> and type 7 in NSSA area provided you haven't manually defined "no
> redistribution" on the NSSA area.
>
> On the other hand, if your R5 is just an NSSA ABR between two OSPF
> areas and the Acual ASBR is another router, then what you're seeing is expected.
>
>
> On 9/23/07, Han Solo <hansolo@ccieunix.com> wrote:
>>
>> So at this point I guess I am asking myself is if I got to an ospf
>> NSSA ASBR and issue the command " show ip ospf database " and I see
>> 20 Extenal Type 5 LSA's , what would stop this router from converting
>> them into OSPF type 7 and sending them into the nssa area ?
>>
>>
>>
>>
>>
>>
>> On Sun, 23 Sep 2007, Han Solo wrote:
>>
>>> Check my sanity please. If R5 is an ospf ASBR and has Area 10
>>> connected
>> as an
>>> NSSA , and R4 is an area 10 NSSA internal router. Should R4 see all
>>> of
>> R5
>>> External Type 5 LSA's as N2 ? If I do a "show ip ospf database" on
>>> R5
>> the
>>> NSSA only ASBR , I see like 12 Ext Type 5 Prefixes. Should this R5
>>> not convert them to Type 7 and pass them to R4 and I should see them
>>> as Type
>> 7 N2
>>> on the Internal R4 router.
>>>
>>> tia
>>>
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