Re: OSPF ADV Router is not-reachable

Thanks Brian,

it's more than clear now!

On Thu, Dec 13, 2012 at 4:38 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:

> That's normal. This is a convergence optimization of OSPF in which it
> retains old LSAs until the MAXAGE is reached. The idea is that if the
> neighbor temporarily flaps, once they come back and they send a database
> descriptor you will realize that you already have their LSAs in the
> database from before, and the only thing you need to do is update the
> neighbor as reachable and reset the age & checksum. Otherwise OSPF would
> have to go through full flooding every time there is a neighbor flap. If
> you wait an hour (MAXAGE) you will see the LSA eventually disappear.
> Normally only the originator of the LSA can prematurely flush the LSA out
> of the database by reflooding with MAXAGE, and if that router is cut off
> from the entire OSPF network it cannot flood, hence your case.
>
>
> HTH,
>
> Brian McGahan, CCIE #8593 (R&S/SP/Security)
> bmcgahan_at_INE.com
>
> Internetwork Expert, Inc.
> http://www.INE.com
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> ccie99999
> Sent: Thursday, December 13, 2012 5:56 AM
> To: Cisco certification
> Subject: OSPF ADV Router is not-reachable
>
> Hello friends,
>
> I'm working on OSPF in these days and I don't undertand this thing:
>
> I've a stable topology and I've one router (R3) that is my exit point for
> my nssa area..
> R3 indeed is configured as nssa no-summary.
> And in the routers in this area (it's area2) get him as only summary LSAs.
>
> Summary Net Link States (Area 2)
>
> Link ID ADV Router Age Seq# Checksum
> 0.0.0.0 150.1.3.3 1091 0x80000001 0x00BED9
>
> If now I decide to kill R3 (shut all interfaces) and even do a clear of
> ospf process, I still see the summary in the ospf database.
>
> If then I check the LSA1 on in it I see ADV Router is not-reachable.
>
> Rack1SW1#show ip ospf database router 150.1.3.3
>
> Adv Router is not-reachable
> LS age: 2292
>
> I don't understand the reason it's still there. Should't be flushed? and
> why by design it's not?
>
> thank you
>
>
> --
> @ccie99999
>
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