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List:       ms-ospf
Subject:    Re: Flushing of MaxAge LSAs from Database.
From:       Acee Lindem <acee () REDBACK ! COM>
Date:       2004-05-17 1:26:32
Message-ID: 07f801c43bad$fd9dba50$0202a8c0 () aceeinspiron
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----- Original Message -----
From: "Singh, Gurpreet" <Gurpreet.Singh@SPIRENTCOM.COM>
To: <OSPF@PEACH.EASE.LSOFT.COM>
Sent: Saturday, May 15, 2004 8:07 PM
Subject: Flushing of MaxAge LSAs from Database.


> Hi
>
> I have a question regarding the flushing of MaxAge LSAs in the OSPF
> Database.
>
> RFC 2328 does say that premature flushing of LSAs can only be done by the
> originator of the LSA only but is this valid for naturally aged LSAs in a
> router's Database also. i.e. Can only the Originating router flush the
> naturally aged LSA (when the LS age reaches MaxAge) or any router can flush
> the naturally aged LSA.

Hi Gurpreet,

Since the LSA age has reached MaxAge, this isn't considered "premature" aging
and any router detecting the condition will flood the MaxAged LSA. This has
always seemed like a questionable design choice to me since it may result in
many routers flooding the MaxAge LSA at approximately the same time.
However, our implementation follows the specification.

Hope this helps,
Acee


>
>
>
> According to RFC 2328 Section 14
>
> "An LSA's LS age is never incremented past the value MaxAge. LSAs
> having age MaxAge are not used in the routing table calculation. As
> a router ages its link state database, an LSA's LS age may reach
> MaxAge.[21] At this time, the router must attempt to flush the LSA
> from the routing domain. This is done simply by reflooding the
> MaxAge LSA just as if it was a newly originated LSA (see Section
> 13.3)."
>
> and Section 14.1
>
> "A router may only prematurely age its own self-originated LSAs.
> The router may not prematurely age LSAs that have been
> originated by other routers. "
>
> Thanks
>
> Gurpreet
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