[c-nsp] NSSA default route forwarding address

[Dimitrios Kalogeras]

cisco-nsp-request at puck.nether.net wrote:
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Tue, 5 Dec 2006 14:10:06 -0500 (EST)
> From: "Justin M. Streiner" <streiner at cluebyfour.org>
> Subject: Re: [c-nsp] NSSA default route forwarding address and default
> 	route selection
> To: cisco-nsp at puck.nether.net
> Message-ID: <Pine.LNX.4.64.0612051400360.8224 at whammy.cluebyfour.org>
> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
> 
> On Tue, 5 Dec 2006, Dimitrios Kalogeras wrote:
> 
>> Hi to all of you,
>>
>> I have the following scenario:
>>
>> A router which is a member of the area 0 and member of NSSA  generates
>> default route inside the NSSA. The  router has two links  and no
>> loopback in  which belong in this NSSA area. The router selects as
>> forwarding address the biggest IP address and not the one with the
>> smallest ospf cost nor does he selects 0.0.0.0 as a forwarding address.
> 
Hi Justin,

> This is correct.  If an OSPF speaking router does not have a loopback 
> address, it will use the highest-numbered IP address that it has on one of 
> its interfaces as its router ID.  If the router in question has many 
> interfaces or its overall topology changes often, you could introduce some 
> IGP instability if a new interface is added with a higher IP address than 
> the existing router ID.  This would cause your OSPF adjacencies to drop 
> since hello packets would be sent out with a router ID different than the 
> ones that originally established the adjacency.  It would also likely 
> cause your OSPF process to reset.
> 
My router has a loopback interface in area 0 and a router-id set
specifically set for that reason. However the default route generation
was for the nssa area and not for the backbone area. Does this mean I
have to create another one for the nssa area ?

Regards,


Dimitri