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RE: OSPF STUB/TOT-STUB posted 09/05/2003
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You can really configure it all over or on the ABR only and it will
work, but it's the ABR that kills the LSA 3's.  

1.  area x stub on all routers (else you get an area type mismatch, E
bit set to 0 when stub is configured)
2.  area x stub no-summary on ABR (tells ABR not to send type 3's into
the area, E bit is 0) 

The key reason here is that the hello packet is modified (E bit = 0)
when you set an area to stub.  All adjacencies on an interface much
match, thus it must be done on all routers participating in the area.
The hello packet is not changed any further when configuring no-summary.
No-summary is configured on the ABR(s) and tells it not to send LSA 3
into the area.  The internal stub routers don't really "know" what
they're missing :)

http://www.cisco.com/warp/customer/104/3.html#13.0

HTH

Allen G. McClure
CCNP/CCDP/MCSE
Yum! Brands, Inc.
Sr. Network Analyst
allen.mcclure@xxxxxxx
 
 
 


-----Original Message-----
From: Rajagopal S [mailto:raj_ccie@xxxxxxxxx] 
Sent: Friday, September 05, 2003 3:05 PM
To: John Matijevic; ccielab@xxxxxxxxxxxxxx
Subject: Re: OSPF STUB/TOT-STUB


Hi John,
 
For totally stub area, i think we need to configure both the ABR and the
internal router with no-summary command.
 
I just want to confirm here if ospf the stub area fields will match in
case we configure differently on these routers. And after this command
the area acts like a stub area and not as a totally stub area (with area
stub in one router and area stub no-summary on the other).
 
Cheers
Raj

John Matijevic <matijevi@xxxxxxxxxxxxx> wrote:
Hello Rajagopal,
I believe you have configured a totally stubby area, when you configure
this you only configure one-side with the no-summary command. Sincerely,
Matijevic
----- Original Message ----- 
From: "Rajagopal S" 
To: 
Sent: Friday, September 05, 2003 10:59 AM
Subject: OSPF STUB/TOT-STUB


> Hi group,
> I noticed a strange thing today...
>
> I was practicing on OSPF STUB and TOTALLY stub araes. I have 2 routers
connected on a point to point FR link.
>
> All characteristics of stub and totally stub are working fine.
>
> I changed the configurations of the routers such that one router was
configured for stub and another for totally-stub.
>
> I had changed the router's configs as below:
>
> Router - A :
>
> router ospf 1
> log-adjacency-changes
> area 1 stub no-summary
>
> Router - B:
> router ospf 1
> log-adjacency-changes
> area 1 stub
>
>
> Even after this, the OSPF neighbor relation was on and routing 
> information
was like as a Stub area in Router - A. Is this possible ? Is it
documented ?
>
> how can a stub and a totally stub area talk ? arent the stub fields
different for these?
>
> Cheers
> Raj
>
>
>
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