From: Shamin (ccie.xpert@gmail.com)
Date: Wed Aug 22 2007 - 06:24:35 ART
Dear Subodh,
This is as per cisco website and as far as i know :
Each OSPF LSA has an age, which indicates whether the LSA is still valid.
Once the LSA reaches the maximum age (one hour), it is discarded. During the
aging process, the originating router sends a refresh packet every 30
minutes to refresh the LSA. Refresh packets are sent to keep the LSA from
expiring, whether there has been a change in the network topology or not.
Checksumming is performed on all LSAs every 10 minutes. The router keeps
track of LSAs it generates and LSAs it receives from other routers. The
router refreshes LSAs it generated; it ages the LSAs it received from other
routers.
http://www.cisco.com/en/US/products/sw/iosswrel/ps1826/products_feature_guide09186a0080087d4d.html
But I will appreciate if you can clarify me as to the differences between
"ip ospf flood reduction " & " ip ospd demand -circuit"
Regards
Shamin
On 8/22/07, subodh.rawat@wipro.com <subodh.rawat@wipro.com> wrote:
>
>
> Just to correct you: This refreshment of LSA takes place after 1 hour
> not 30 minutes.
>
> Subodh
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> eicc tester
> Sent: Wednesday, August 22, 2007 4:38 AM
> To: Shamin; Cisco certification
> Subject: Re: IP ospf demand-circuit V/S IP ospf flood reduction ???
>
> Hi
>
> "ip ospf flood reduction" just avoid the refreshement of LSA every 30
> minutes.
>
> "ip ospf demand circuit" mean that a link which is under an OSPF area
> , don,t send OSPF hello packet all the time. This avoid the fact of
> bring the circuit (probaly and dial or isdn) just for sent hello packet
> periodically, the neigbhor relations is still maintaned.
>
>
> Shamin <ccie.xpert@gmail.com> wrote:
> Hi All,
>
> Can any one tell me , when the commands "ip ospf flood reduction" is
> used over " ip ospf demand circuit" .
> I know that, "Ip ospf demand circuit is used in point to point
> connections.
> Does that mean, ip ospf flood reduction"
> is used in Broadcast and NBMA OSPF networks. I am bit confused as to
> which command to apply in a particular scenario, mainly if the question
> asks to reduce the "paranoid updates" in ospf that occurs every 30mins.
>
> Thanks in advance.
>
> Regards
> Shamin
>
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